HO W S WINSTON (US)
| WO1997040904A1 | 1997-11-06 |
| US4820343A | 1989-04-11 | |||
| NL8903039A | 1991-07-01 | |||
| US6171563B1 | 2001-01-09 | |||
| US20010029810A1 | 2001-10-18 |
|
| WHAT IS CLAIMED IS : 1. A combined supported liquid membrane (SLM)/strip dispersion process for the removal and recovery of one or more target species from a feed solution containing the target species comprising (a) treating a feed solution containing one or more target species on one side of the SLM embedded in a microporous support material to remove the target species by the use of a strip dispersion on the other side of the SLM, the strip dispersion being formed by dispersing an aqueous strip solution in an organic liquid comprising an extractant, using a mixer ; and (b) allowing the strip dispersion or a part of the strip dispersion to separate into two phases, the organic liquid phase and the aqueous strip solution phase containing a concentrated solution of the target species. |
| 2. The process of Claim 1 wherein the microporous support material is selected from the group consisting of polypropylene, polytetrafluoroethylene, polyethylene, polysulfone, polyethersulfone, polyetheretherketone, polyimide, polyamide, and mixtures thereof. |
| 3. The process of Claim 1 wherein the organic liquid of the strip dispersion further comprises a modifier in a hydrocarbon solvent or mixture. |
| 4. The process of Claim 3 wherein the organic liquid of the strip dispersion comprises about 2 wt. % to about 100 wt. % extractant and about 0 wt. % to about 20 wt. % modifier in a hydrocarbon solvent or mixture.
|
| 5. The process of Claim 4 wherein the organic liquid of the strip dispersion comprises about 5 wt. % to about 40 wt. % extractant and about 1 wt. % to about 10 wt. % modifier in a hydrocarbon solvent or mixture. |
| 6. The process of Claim 3 wherein the modifier is selected from the group consisting of alcohols, nitrophenyl alkyl ethers, trialkyl phosphates, and mixtures thereof. |
| 7. The process of Claim 6 wherein the alcohol is selected from the group consisting of hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadacanol, octadecanol, and mixtures thereof. |
| 8. The process of Claim 6 wherein the nitrophenyl alkyl ether is selected from the group consisting of o-nitrophenyl octyl ether (o-NPOE), o-nitrophenyl heptyl ether, o-nitrophenyl hexyl ether, o-nitrophenyl pentyl ether (o-NPPE), o-nitrophenyl butyl ether, o-nitrophenyl propyl ether, and mixtures thereof. |
| 9. The process of Claim 6 wherein the trialkyl phosphate is selected from the group consisting of tributyl phosphate, tris (2-ethylhexyl) phosphate, and mixtures thereof. |
| 10. The process of Claim 3 wherein the hydrocarbon solvent is selected from a group consisting of n-decane ; n-undecane ; n-dodecane ; n-tridecane ; n- tetradecane ; isodecane ; isoundecane ; isododecane ; isotridecane ; isotetradecane ; isoparaffinic hydrocarbon solvent having a flash point of
92°C, a boiling point of 254°C, a viscosity of 3 cp at 25°C, and a density of 0. 791 g/ml (at 15. 6°C)) ; and mixtures thereof. |
| 11. The process of Claim 1 wherein the target species comprises one or more metals or one or more radionuclides. |
| 12. The process of Claim 11 wherein the aqueous strip solution of the strip dispersion comprises an acid. |
| 13. The process of Claim 12 wherein the acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, and mixtures thereof. |
| 14. The process of Claim 11 wherein the metal is selected from the group consisting of cobalt, copper, zinc, nickel, mercury, lead, cadmium, silver, europium, lanthanum, neodymium, praseodymium, gadolinium, selenium, and mixtures thereof. |
| 15. The process of Claim 14 wherein the metal is selected from the group consisting of cobalt, copper, zinc, nickel, mercury, and mixtures thereof. |
| 16. The process of Claim 11 wherein the metal is selected from the group consisting of calcium, magnesium, zinc, and mixtures thereof. |
| 17. The process of Claim 11 for the removal of one or more radionuclides.
|
| 18. The process of Claim 11 wherein the radionuclide is selected from the group consisting of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, americium, and mixtures thereof. |
| 19. The process of Claim 11 for the removal of strontium. |
| 20. The process of Claim 11 wherein the feed solution is treated at a flux of about 3 g/(m2*hr) or higher. |
| 21. The process of Claim 11 wherein the extractant is di (2-butyloctyl) monothiophosphoric acid (C12 MTPA). |
| 22. The process of Claim 11 wherein the extractant comprises an alkyl phenylphosphonic acid. |
| 23. The process of Claim 22 wherein the alkyl group of the alkyl phenylphosphonic acid is paraffinic (saturated) and has from 6 to 26 carbon atoms. |
| 24. The process of Claim 22 wherein the alkyl phenylphosphonic acid is selected from the group consisting of 2-butyl-l-octyl phenylphosphonic acid (BOPPA), 2-hexyl-l-decyl phenylphosphonic acid, 2-octyl-l-decyl/2-hexyl- 1-dodecyl phenylphosphonic acid, 2-octyl-1-dodecyl phenylphosphonic acid, hexyl phenylphosphonic acid, heptyl phenylphosphonic acid, octyl phenylphosphonic acid, nonyl phenylphosphonic acid, decyl phenylphosphonic acid, undecyl phenylphosphonic acid, dodecyl phenylphosphonic acid, tridecyl phenylphosphonic acid, tetradecyl phenylphosphonic acid, pentadecyl phenylphosphonic acid, hexadecyl
phenylphosphonic acid, heptadecyl phenylphosphonic acid, octadecyl phenylphosphonic acid, nonadecyl phenylphosphonic acid, decadecyl phenylphosphonic acid, undecadecyl phenylphosphonic acid, dodecadecyl phenylphosphonic acid, tridecadecyl phenylphosphonic acid, tetrdecadecyl phenylphosphonic acid, pentadadecyl phenylphosphonic acid, hexadecadecyl phenylphosphonic acid, and mixtures thereof. |
| 25. The process of Claim 22 wherein the alkyl phenylphosphonic acid is 2-butyl- 1-octyl phenylphosphonic acid (BOPPA). |
| 26. The process of Claim 22 wherein the alkyl phenylphosphonic acid is 2- hexyl-1-decyl phenylphosphonic acid. |
| 27. The process of Claim 22 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid. |
| 28. The process of Claim 22 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-dodecyl phenylphosphonic acid. |
| 29. The process of Claim 22 for the removal of one or more radionuclides. |
| 30. The process of Claim 29 wherein the radionuclide is selected from the group consisting of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, americium, and mixtures thereof. |
| 31. The process of Claim 29 for the removal of strontium.
|
| 32. The process of Claim 31 wherein alkyl phenylphosphonic acid is 2-butyl-1- octyl phenylphosphonic acid (BOPPA). |
| 33. The process of Claim 31 wherein the alkyl phenylphosphonic acid is 2- hexyl-1-decyl phenylphosphonic acid. |
| 34. The process of Claim 31 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid. |
| 35. The process of Claim 31 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-dodecyl phenylphosphonic acid. |
| 36. The process of Claim 31 wherein the feed solution is treated to remove strontium to a concentration of 8 pico Curie per liter (8 pCi/L) or lower. |
| 37. The process of Claim 22 for the removal of metal. |
| 38. The process of Claim 37 wherein the metal is selected from the group consisting of calcium, magnesium, zinc, and mixtures thereof. |
| 39. The process of Claim 38 wherein the alkyl phenylphosphonic acid is 2-butyl- 1-octyl phenylphosphonic acid. |
| 40. The process of Claim 38 wherein the alkyl phenylphosphonic acid is 2- hexyl-1-decyl phenylphosphonic acid. |
| 41. The process of Claim 38 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid.
|
| 42. The process of Claim 38 wherein the alkyl phenylphosphonic acid is 2-octyl- 1-dodecyl phenylphosphonic acid. |
| 43. The process of Claim 1 wherein the target species is selected from the group consisting of penicillin, organic acids, and combinations thereof. |
| 44. The process of Claim 43 wherein the penicillin is selected from the group consisting of penicillin G and penicillin V. |
| 45. The process of Claim 44 wherein the pencillin is penicillin G. |
| 46. The process of Claim 43 wherein the organic acid is selected from a group consisting of phenylalanine, acrylic acid, lactic acid, proprionic acid, citric acid, acetic acid, and combinations thereof. |
| 47. The process of Claim 43 wherein the aqueous strip solution of the strip dispersion comprises a base. |
| 48. The process of Claim 47 wherein the base is selected from the group consisting of sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), ammonium hydroxide (NH40H), and tetramethylammonium hydroxide ((CH) 4NOH), and mixtures thereof. |
| 49. A combined supported liquid membrane (SLM)/strip dispersion process for the removal and recovery of one or more target species from a feed solution containing the target species comprising (1) treating a feed solution containing one or more target species on one side of the SLM, embedded in a microporous support material with
an interfacial polymerized layer or layers, to remove the target species by the use of a strip dispersion on the other side of the SLM, the strip dispersion being formed from dispersing an aqueous strip solution in an organic liquid comprising an extractant using a mixer ; and (2) allowing the strip dispersion or a part of the strip dispersion upon standing (without mixing) to separate into two phases, the organic liquid phase and the aqueous strip solution phase containing a concentrated solution of the target species. |
| 50. The process of Claim 49 wherein the interfacial polymerized layer is derived from trimesoyl chloride and lysine. |
| 51. The process of Claim 49 wherein the interfacial polymerized layer is derived from trimesoyl chloride and 1- (2-aminoethyl) piperazine. |
| 52. The process of Claim 49 wherein the interfacial polymerized layer is derived from trimesoyl chloride and triethylenetetraamine. |
| 53. The process of Claim 49 wherein the interfacial polymerized layer is derived from trimesoyl chloride and piperazine. |
| 54. The process of Claim 49 wherein the interfacial polymerized layer is derived from trimesoyl chloride and hexamethylenediamine. |
| 55. The process of Claim 49 wherein the microporous support material is selected from the group consisting of polypropylene,
polytetrafluoroethylene, polyethylene, polysulfone, polyethersulfone, polyetheretherketone, polyimide, polyamide, and mixtures thereof. |
| 56. The process of Claim 49 wherein the target species is selected from the group consisting of metals, radionuclides, penicillins, and organic acids. |
| 57. The process of Claim 49 wherein the organic liquid of the strip dispersion further comprises a modifier in a hydrocarbon solvent or mixture. |
| 58. The process of Claim 57 wherein the organic liquid of the strip dispersion comprises 2 wt. %-100 wt. % extractant and 0 wt. %-20 wt. % modifier in a hydrocarbon solvent or mixture. |
| 59. The process of Claim 57 wherein the organic liquid of the strip dispersion comprises 5 wt. %-40 wt. % extractant and 1 wt. %-10 wt. % modifier in a hydrocarbon solvent or mixture. |
| 60. The process of Claim 57 wherein the modifier is selected from the group consisting of alcohols, nitrophenyl alkyl ethers, trialkyl phosphates, and mixtures thereof. |
| 61. The process of Claim 60 wherein the alcohol is selected from the group consisting of hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadacanol, octadecanol, and mixtures thereof. |
| 62. The process of Claim 60 wherein the nitrophenyl alkyl ether is selected from the group consisting of o-nitrophenyl octyl ether (o-NPOE), o-nitrophenyl
heptyl ether, o-nitrophenyl hexyl ether, o-nitrophenyl pentyl ether (o-NPPE), o-nitrophenyl butyl ether, o-nitrophenyl propyl ether, and mixtures thereof. |
| 63. The process of Claim 60 wherein the trialkyl phosphate is selected from the group consisting of tributyl phosphate, tris (2-ethylhexyl) phosphate, and mixtures thereof. |
| 64. The process of Claim 57 wherein the hydrocarbon solvent is selected from a group consisting of n-decane, n-undecane, n-dodecane, n-tridecane, n- tetradecane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isoparaffinic hydrocarbon solvent (for example, with a flash point of 92°C, a boiling point of 254°C, a viscosity of 3 cp (at 25°C), and a density of 0. 791 g/ml (at 15. 6°C)), and mixtures thereof. |
| 65. A composition comprising an alkyl phenylphosphonic acid extractant. |
| 66. The composition of Claim 65 wherein the alkyl group of the alkyl phenylphosphonic acid is paraffinic (saturated) and has from 6 to 26 carbon atoms. |
| 67. The composition of Claim 65 wherein the alkyl phenylphosphonic acid is selected from the group consisting of 2-butyl-l-octyl phenylphosphonic acid (BOPPA), 2-hexyl-l-decyl phenylphosphonic acid, 2-octyl-1-decyl/2-hexyl- 1-dodecyl phenylphosphonic acid, 2-octyl-l-dodecyl phenylphosphonic acid, hexyl phenylphosphonic acid, heptyl phenylphosphonic acid, octyl phenylphosphonic acid, nonyl phenylphosphonic acid, decyl phenylphosphonic acid, undecyl phenylphosphonic acid, dodecyl
phenylphosphonic acid, tridecyl phenylphosphonic acid, tetradecyl phenylphosphonic acid, pentadecyl phenylphosphonic acid, hexadecyl phenylphosphonic acid, heptadecyl phenylphosphonic acid, octadecyl phenylphosphonic acid, nonadecyl phenylphosphonic acid, decadecyl phenylphosphonic acid, undecadecyl phenylphosphonic acid, dodecadecyl phenylphosphonic acid, tridecadecyl phenylphosphonic acid, tetrdecadecyl phenylphosphonic acid, pentadadecyl phenylphosphonic acid, hexadecadecyl phenylphosphonic acid, and mixtures thereof. |
| 68. The composition of Claim 65 wherein the alkyl phenylphosphonic acid is 2- butyl-1-octyl phenylphosphonic acid (BOPPA). |
| 69. The composition of Claim 65 wherein the alkyl phenylphosphonic acid is 2- hexyl-1-decyl phenylphosphonic acid. |
| 70. The composition of Claim 65 wherein the alkyl phenylphosphonic acid is 2- octyl-1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid. |
| 71. The composition of Claim 65 wherein the alkyl phenylphosphonic acid is 2- octyl-1-dodecyl phenylphosphonic acid. |
| 72. A process for the synthesis of an alkyl phenylphosphonic acid comprising (1) reacting an alcohol containing from 6 to 26 carbon atoms and phenylphosphonyl dichloride in an organic solvent ; (2) quenching the reaction mixture by adding concentrated HCl and ice ; (3) extracting the alkyl phenylphosphonic acid from the reaction mixture using a solvent ;
(4) washing the alkyl phenylphosphonic acid/solvent solution with 1 M HC1 solution ; (5) drying the alkyl phenylphosphonic acid/solvent solution ; and (6) recovering the alkyl phenylphosphonic acid by evaporating the solvent from the solution. |
| 73. The process of Claim 72 wherein the alcohol is 2-butyl-l-octanol. |
| 74. The process of Claim 72 wherein the alcohol is 2-hexyl-1-decanol. |
| 75. The process of Claim 72 wherein the alcohol is 2-octyl-1-decanol/2-hexyl-1- dodecanol. |
| 76. The process of Claim 72 wherein the alcohol is 2-octyl-1-dodecanol. |
| 77. The process of Claim 72 wherein the solvent in step (1) is pyridine. |
| 78. The process of Claim 72 wherein step (1) is performed at a temperature between about 0 and 10°C. |
| 79. The process of Claim 72 wherein the solvent in step (3) is toluene. |
| 80. The process of Claim 72 wherein the alkyl phenylphosphonic acid/solvent solution is dried using MgSO4. |
| 81. The compound di (2-butyloctyl) monothiophosphoric acid. |
| 82. An extractant comprising a dialkyl monothiophosphoric acid.
|
| 83. The extractant of claim 82 wherein the dialkyl monothiophosphoric acid is selected from a group consisting of di (2-ethylhexyl) monothiophosphoric acid, di (3, 5, 5-trimethylhexyl) monothiophosphoric acid, di (3, 7-dimethyloctyl) monothiophosphoric acid, and di (2- butyloctyl) monothiophosphoric acid. |
| 84. The extractant of claim 83 wherein the dialkyl monothiophosphoric acid is di (2-butyloctyl) monothiophosphoric acid. |
| 85. A method for the manufacture of an extractant for use in a combined supported liquid membrane/strip dispersion process comprising : (1) mixing phosphorus pentasulfide (P2S5) with an alcohol and heating the mixture to form thiophosphate intermediates ; and (2) hydrolyzing the thiophosphate intermediates to form a dialkyl monothiophosphoric acid corresponding to the alcohol employed in step (1). |
| 86. The method of claim 85 wherein the alcohol is selected from the group consisting of 2-ethyl-l-hexanol, 3, 5, 5-trimethyl-l-hexanol, 3, 7-dimethyl-1- octanol, and 2-butyl-l-octanol. |
| 87. The method of claim 85 wherein the alcohol is 2-butyl-l-octanol. |
| 88. The method of claim 85 wherein the thiophosphate intermediates are hydrolyzed with mineral acid. |
| 89. The method of claim 88 wherein the mineral acid is HC1.
|
| 90. The method of claim 85 wherein step (2) is monitored to determine when hydrolysis is complete. |
| 91. The method of claim 90 wherein step (2) is monitored by FTIR. |
| 92. The method of claim 85 wherein the mixture in step (1) is heated to a temperature range from about 60° C to about 160° C. |
| 93. The method of claim 92 wherein the temperature range for step (1) is from about 70°C to about 145°C. |
| 94. The method of claim 92 wherein the temperature range for step (1) is from about 80°C to about 100°C. |
| 95. The method of claim 85 wherein a reaction time for step (1) of the process comprises from about 1 hour to about 60 hours. |
| 96. The method of claim 95 wherein the reaction time for step (1) is from about 1 hour to about 24 hours. |
| 97. The method of claim 95 wherein the reaction time for step (1) is from about 1 hour to about 6 hours. |
| 98. The method of claim 85 wherein the extractant is di (2-ethylhexyl) monothiophosphoric acid. |
| 99. The method of claim 85 wherein the extractant is di (3, 5, 5-trimethylhexyl) monothiophosphoric acid.
|
| 100. The method of claim 85 wherein the extractant is di (3, 7-dimethyloctyl) monothiophosphoric acid. |
| 101. The method of claim 85 wherein the extractant is di (2- butyloctyl) monothiophosphoric acid. |
| 102. The method of claim 85 wherein a reaction time for step (2) of the process is from about 1 hour to about 10 hours, and the temperature range is from about 60°C to about 120°C. |
| 103. The method of claim 102 wherein the reaction time for step (2) is from about 6 hours to about 8 hours, and the temperature range is from about 70°C to about 90°C. |
| 104. The method of claim 102 wherein the reaction time for step (2) is from about 3 hours to about 4 hours and the temperature range is from about 100°C to about 120°C. |
COMBINED SUPPORTED LIQUID MEMBRANE/STRIP DISPERSION PROCESSES AND EXTRACTANTS FIELD OF THE INVENTION The present invention relates to the removal and recovery of target species, such as metals, radionuclides, penicillin, and organic acids, from feed solutions, such as waste waters and process streams, using supported liquid membrane technology.
BACKGROUND OF THE INVENTION Liquid membranes combine extraction and stripping, which are normally carried out in two separate steps in conventional processes such as solvent extractions, into one step. A one-step liquid membrane process provides the maximum driving force for the separation of a targeted species, leading to the best clean-up and recovery of the species (W. S. Winston Ho and Kamalesh K. Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992).
There are two types of liquid membranes : (1) supported liquid membranes (SLMs) and (2) emulsion liquid membranes (ELMs). In SLMs, the liquid membrane phase is the organic liquid imbedded in pores of a microporous support, e. g., microporous polypropylene hollow fibers (W. S. Winston Ho and Kamalesh K.
Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992). When the organic liquid contacts the microporous support, it readily wets the pores of the support, and the SLM is formed.
For the extraction of a target species from a feed solution, the organic-based SLM is placed between two aqueous solutions-the feed solution and the strip
solution where the SLM acts as a semi-permeable membrane for the transport of the target species from the feed solution to the strip solution. The organic liquid in the SLM is immiscible in the aqueous feed and strip streams and contains an extractant, a diluent which is generally an inert organic solvent, and sometimes a modifier.
The use of SLMs to remove metals from aqueous feed solutions has been long pursued in the scientific and industrial community. The removal of metals, including cobalt, copper, nickel, zinc, cadmium, and gallium, from aqueous solutions has been studied (R. S. Juang and J. D. Jiang,"Rate-controlling Mechanism of Cobalt Transport through Supported Liquid Membranes Containing Di (2-ethylhexyl) Phosphoric Acid,"Sep. Sci. Technol., 29, 223-237 (1994) ; T.
Saito,"Selective Transport of Copper (I, II), Cadmium (II), and Zinc (II) Ions through a Supported Liquid Membrane Containing Bathocuproine, Neocuproine, or Bathophenanthroline,"Sep. Sci. Technol., 29, 1335-1346 (1994) ; M. Teramoto, N.
Ohnishi, and H. Matsuyama,"Effect of Recycling of Feed Solution on the Efficiency of Supported Liquid Membrane Module,"Sep. Sci. Technol., 29, 1749- 1755 (1994) ; F. F. Zha, A. G. Fane, and C. J. D. Fell,"Liquid Membrane Processes for Gallium Recovery from Alkaline Solutions,"Ind. Eng. Chem. Res., 34, 1799- 1809 (1995) ; S. B. Kunungo and R. Mohapatra,"Coupled Transport of Zn (II) through a Supported Liquid Membrane Containing bis (2, 4, 4-Trimethylpentyl) Phosphinic Acid in Kerosene. II Experimental Evaluation of Model Equations for Rate Process under Different Limiting Conditions,"J. Membrane Sci., 105, 227-235 (1995)).
Recently, the removal of metals, including copper, zinc, cadmium, and palladium, with SLMs has been described (N. Aouad, G. Miquel-Mercier, E.
Bienvenue, E. Tronel-Peyroz, G. Jeminet, J. Juillard, and P. Seta,"Lasalocid
(X537A) as a Selective Carrier for Cd (II) in Supported Liquid Membranes,"J.
Membrane Sci., 139, 167-174 (1998) ; J. A. Daoud, S. A. El-Reefy, and H. F. Aly, "Permeation of Cd (II) Ions through a Supported Liquid Membrane Containing Cyanex-302 in Kerosene,"Sep. Sci. Technol., 33, 537-549 (1998) ; J. Vander Linden and R. F. De Ketelaere,"Selective Recuperation of Copper by Supported Liquid Membrane (SLM) Extraction,"J. Membrane Sci., 139, 125-135 (1998) ; M. E.
Campderrós, A. Acosta, and J. Marchese,"Selective Separation of Copper with LIX 864 in a Hollow Fiber Module,"Talanta, 47, 19-24 (1998) ; M. Rovira and A. M.
Sastre,"Modelling of Mass Transfer in Facilitated Supported Liquid-Membrane Transport of Palladium (II) Using Di- (2-ethylhexyl) Thiophosphoric Acid,"J.
Membrane Sci., 149, 241-250 (1998) ; J. C. Lee, J. Jeong, J. T. Park, I. J. Youn, and H. S. Chung,"Selective and Simultaneous Extractions of Zn and Cu Ions by Hollow Fiber SLM Modules Containing HEH (EHP) and LIX84,"Sep. Sci. Technol., 34, 1689-1701 (1999) ; F. Valenzuela, C. Basualto, C. Tapia, and J. Sapag,"Application of Hollow-Fiber Supported Liquid Membranes Technique to the Selective Recovery of a Low Content of Copper from a Chilean Mine Water,"J. Membrane Sci., 155, 163-168 (1999) ; M. Oleinikova, C. González, M. Valiente, and M. Munoz, "Selective Transport of Zinc through Activated Composite Membranes Containing Di (2-ethylhexyl) Dithiophosphoric Acid as a Carrier,"Polyhedron, 18, 3353-3359 (1999)).
The extraction of rare earth metals, including europium, lanthanum, neodymium, praseodymium, and gadolinium with SLMs has also been investigated (C. Nakayama, S. Uemiya, and T. Kojima,"Separation of Rare Earth Metals Using a Supported Liquid Membrane with DTPA,"J. Alloys Compounds, 225, 288-290 (1995) ; R. S. Juang and S. H. Lee,"Analysis of the Transport Rates of Europium (III) across an Organophosphinic Acid Supported Liquid Membrane,"J.
Membrane Sci., 110, 13-23 (1996) ; M. R. Yaftian, M. Burgard, C. B. Dieleman and D. Matt,"Rare-earth Metal-ion Separation Using a Supported Liquid Membrane Mediated by a Narrow Rim Phosphorylated Calix [4] arene," J. Membrane Sci., 144, 57-64 (1998)).
In addition to the removal of metals, the use of SLMs to remove radionuclides from aqueous feed solutions has been long pursued in the scientific and industrial community. Nechaev et al. (A. F. Nechaev, V. V. Projaev, V. P.
Kapranchik,"Supported Liquid Membranes in Radioactive Waste Treatment Processes : Recent Experience and Prospective", in S. Slate, R. Baker, and G. Benda, eds., Proceedings of Fifth International Conference on Radioactive Waste Management and Environmental Remediation, Volume 2, American Society of Mechanical Engineers, New York, 1995) have reported on the experience and prospective of using SLMs in radioactive waste treatment processes, and the transport of uranyl ion across SLMs has been studied extensively (J. P. Shukla and S. K. Misra,"Uranyl Ion Transport Across Tri-n-butyl Phosphate/n-Dodecane Liquid Membranes", Proceedings of the International Symposium on Uranium Technology, Bhabha Atomic Research Centre, Bombay, India, pp. 939-946, 1991 ; M. A. Chaudhary,"Separation of Some Metal Ions Using Coupled Transport Supported Liquid Membranes", in H. Javed, H. Pervez, and R. Qadeer, Modern Trends in Contemporary Chemistry, Scientific Information Division PINSTECH, Islamabad, Pakistan, pp. 123-131, 1993).
Chiarizia et al. (R. Chiarizia, E. P. Horwitz, and K. M. Hodgson, An Application of Supported Liquid Membranes for Removal of Inorganic Contaminants from Groundwater, DOE Report No. DE92006971, 1991) have reviewed and summarized the results of an investigation on the use of SLMs for the
removal of uranium and some inorganic contaminants, including technetium, from the Hanford site groundwater. Chiarizia (R. Chiarizia,"Application of Supported Liquid Membranes for Removal of Nitrate, Technetium (VII) and Chromium (VI) from Groundwater", J. Membrane Sci., 55, 39-64 (1991)) has described the separation of technetium (VII) and uranium (VI) from synthetic Hanford site groundwater using SLMs. Dozol et al. (J. F. Dozol, J. Casas, and A. Sastre, "Stability of Flat Sheet Supported Liquid Membranes in the Transport of Radionuclides from Reprocessing Concentrate Solutions", J. Membrane Sci., 82, 237-246 (1993)) have studied the stability of flat sheet SLMs in the transport of radionuclides.
Recently, Dozol et al. (J. F. Dozol, N. Simon, V. Lamaare, H. Rouquette, S.
Eymard, B. Tournois, D. De Marc, and R. M. Macias,"A Solution for Cesium Removal from High-Salinity Acidic or Alkaline Liquid Waste : the Crown Calix [4] arenes", Sep. Sci. Technol., 34, 877-909 (1999)) have described the use of the extractant, Calix [4] arenes monocrown or biscrown, blocked in 1, 3 alternative cone conformation, in SLMs for the removal of cesium from high-salinity acidic or alkaline liquid waste. Kedari et al. (C. S. Kedari, S. S. Pandit, and A. Ramanujam, "Selective Permeation of Plutonium (IV) through Supported Liquid Membrane Containing 2-Ethylhexyl 2-Ethylhexyl Phosphonic Acid as Ion Carrier", J.
Membrane Sci., 156, 187-196 (1999)) have studied the selective permeation of plutonium (IV) through a SLM containing 2-ethylhexyl 2-ethylhexyl phosphonic acid as the ion carrier. Vinas et al. (C. Vinas, S. Gomez, J. Bertran, J. Barron, F.
Teixidor, J. F. Dozol, H. Rouquette, R. Kivekäs, and R. Sillanpaahave,"C- substituted bis (Dicarbollide) Metal Compounds as Sensors and Extractants of Radionuclides from Nuclear Wastes", J. Organometallic Chem., 581, 188-193
(1999)) have investigated the transport of cesium through the SLMs of C-substituted bis (dicarbollide) metal compounds in the solvent of nitrophenylhexyl ether.
Additionally, the use of SLMs to remove penicillin and organic acids from aqueous feed solutions has attracted considerable attention in the scientific and industrial community. The extraction of penicillin G from aqueous feed solutions has been investigated (C. J. Lee, H. J. Yeh, W. Y. Yang, and C. R. Kan, "Preparation of penicillin G from Phenylacetic Acid in a Supported Liquid Membrane System", Biotechnol. Bioeng., 43, 309-313 (1994) ; R. S. Juang and Y. S.
Lin,"Investigation on Interfacial Reaction Kinetics of Penicillin G and Amberlite LA-2 from Membrane Flux Measurements", J. Membrane Sci., 141, 19-30 (1998)).
The extraction of organic acids, including phenylalanine, acrylic acid, lactic acid, proprionic acid, citric acid, and acetic acid, from aqueous solutions with SLMs has also been studied (L. K. Ju and A. Verma,"Characteristics of Lactic Acid Transport in Supported Liquid Membranes", Sep. Sci. Technol., 29, 2299-2315 (1994) ; J. T. Rockman, E. Kehat, and R. Lavie,"Mathematical Model for Thermally Enhanced Facilitated Transport", Ind. Eng. Chem. Res., 34, 2455-2463 (1995) ; F.
Ozadali, B. A. Glatz, and C. E. Glatz,"Fed-batch Fermentation with and without On-line Extraction for Propionic and Acetic Acid Production by Propionibacterium Acidipropionici", Applied Microb. Biotechnol., 44, 710-716 (1996) ; R. S. Juang and L. J. Chen,"Analysis of the Transport Rates of Citric Acid through a Supported Liquid Membrane Containing Tri-n-octylamine", Ind. Eng. Chem. Res., 35, 1673- 1679 (1996) ; R. S. Juang, S. H. Lee, and R. C. Shiau,"Mass-transfer Modeling of Permeation of Lactic Acid across Amine-mediated Supported Liquid Membranes", J. Membrane Sci., 137, 231-239 (1997) ; R. S. Juang, S. H. Lee, and R. H. Huang,
"Modeling of Amine-facilitated Liquid Membrane Transport of Binary Organic Acids, Sep. Sci. Technol., 33, 2379-2395 (1998)).
One disadvantage of SLMs is their instability due mainly to loss of the membrane liquid (organic solvent, extractant, and/or modifier) into the aqueous phases on each side of the membrane (A. J. B. Kemperman, D. Bargeman, Th. Van Den Boomgaard, H. Strathmann,"Stability of Supported Liquid Membranes : State of the Art", Sep. Sci. Technol., 31, 2733 (1996) ; T. M. Dreher and G. W Stevens, "Instability Mechanisms of Supported Liquid Membranes", Sep. Sci. Technol., 33, 835-853 (1998) ; J. F. Dozol, J. Casas, and A. Sastre,"Stability of Flat Sheet Supported Liquid Membranes in the Transport of Radionuclides from Reprocessing Concentrate Solutions", J. Membrane Sci., 82, 237-246 (1993)). The prior art has attempted to solve this problem through the combined use of SLM with a module containing two set of hollow fibers, i. e., the hollow-fiber contained liquid membrane (W. S. Winston Ho and Kamalesh K. Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992). In this configuration with two sets of microporous hollow-fiber membranes, one carries the aqueous feed solution, and the other carries the aqueous strip solution. The organic phase is contained between the two sets of hollow fibers by maintaining the aqueous phases at a higher pressure than the organic phase. The use of the hollow-fiber contained liquid membrane increases membrane stability, because the liquid membrane may be continuously replenished.
However, this configuration is not advantageous because it requires mixing two sets of fibers to achieve a low contained liquid membrane thickness.
In ELMs, an emulsion acts as a liquid membrane for the separation of the target species from a feed solution. An ELM is created by forming a stable emulsion, such as a water-in-oil emulsion, between two immiscible phases, followed
by dispersion of the emulsion into a third, continuous phase by agitation for extraction. The membrane phase is the oil phase that separates the encapsulated, internal aqueous droplets in the emulsion from the external, continuous phase (W. S.
Winston Ho and Kamalesh K. Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992). The species-extracting agent is contained in the membrane phase, and the stripping agent is contained in the internal aqueous droplets.
Emulsions formed from these two phases are generally stabilized by use of a surfactant. The external, continuous phase is the feed solution containing the target species. The target species is extracted from the aqueous feed solution into the membrane phase and then stripped into the aqueous droplets in the emulsion. The target species can then be recovered from the internal aqueous phase by breaking the emulsion, typically via electrostatic coalescence, followed by electroplating or precipitation.
The use of ELMs to remove metals from aqueous feed solutions has also been long pursued in the scientific and industrial community. ELMs for the removal of metals, including cobalt, copper, zinc, nickel, mercury, lead, cadmium, silver, europium, lanthanum, and neodymium, have been described in detail (W. S.
Winston Ho and Kamalesh K. Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992). The removal of cobalt, copper, and nickel from aqueous solutions by ELMs has also been investigated (J. Strzelbicki and W. Charewicz, "The Liquid Surfactant Membrane Separation of Copper, Cobalt and Nickel from Multicomponent Aqueous Solutions,"Hvdrometallurgy, 5, 243-254 (1980)). The extraction of lanthanoids, including europium, lanthanum, neodymium, and gadolinium, with ELMs has been studied (M. Teramoto, T. Sakuramoto, T.
Koyama, H. Matsuyama, and Y. Miyake,"Extraction of Lanthanoids by Liquid Surfactant Membranes,"Sep. Sci. Technol., 21, 229-250 (1986) ; C. J. Lee, S. S.
Wang, and S. G. Wang,"Extraction of Trivalent Europium via Emulsion Liquid Membrane Containing PC-88A as Mobile Carrier, Ind. Eng. Chem. Res., 33, 1556- 1564 (1994) ; S. A. El-Reefy, M. R. El-Sourougy, E. A. El-Sherif, and H. F. Aly, "Europium Permeation and Separation from Americium Using Liquid Emulsion Membrane,"Anal. Sci., 11, 329-331 (1995)).
Recently, the removal of metals including cobalt, nickel, cadmium, mercury, and lead with ELMs has been reported (M. Samar, D. Pareau, G. Durand, and A.
Chesne,"Purification of Waste Waters Containing Heavy Metals by Surfactant Liquid Membrane Extraction,"in Hydrometall.'94, Pap. Int. Symp., Chapman & Hall, London, UK, 1994, pp. 635-654 ; B. Raghuraman, N. Tirmizi, and J. M.
Wiencek,"Emulsion Liquid Membranes for Wastewater Treatment. Equilibrium Models for Some Typical Metal-Extractant Systems,"Environ. Sci. Technol., 28, 1090-1098 (1994) ; M. T. A. Reis and J. M. R. Carvalho,"Recovery of Heavy Metals by a Combination of Two Processes : Cementation and Liquid Membrane Permeation,"Minerals Eng., 7, 1301-1311 (1994) ; T. Kakkoi, M. Goto, K.
Sugimoto, K. Ohto, and F. Nakashio,"Separation of Cobalt and Nickel with Phenylphosphonic Acid Mono-4-tert-octylphenyl Ester by Liquid Surfactant Membranes,"Sep. Sci. Technol., 30, 637-657 (1995) ; R. S. Juang and J. D. Jiang, "Recovery of Nickel from a Simulated Electroplating Rinse Solution by Solvent Extraction and Liquid Surfactant Membrane,"J. Membrane Sci., 100, 163-170 (1995) ; B. J. Raghuraman, N. P. Tirmizi, B. S. Kim, and J. M. Wiencek,"Emulsion Liquid Membranes for Wastewater Treatment : Equilibrium Models for Lead-and Cadmium-di-2-ethylhexyl Phosphoric Acid Systems,"Environ. Sci. Technol., 29, 979-984 (1995) ; E. Amanatidou, M. N. Stefanut, and A. Grozav,"Method of Cobalt Ion Concentration from Dilute Aqueous Solutions,"Sep. Sci. Technol., 31, 655-664 (1996) ; Q. Li, Q. Liu, and X. Wei,"Separation Study of Mercury through an
Emulsion Liquid Membrane,"Talanta, 43, 1837-1842 (1997) ; H. Kasaini, F.
Nakashio, and M. Goto,"Application of Emulsion Liquid Membranes to Recover Cobalt Ions from a Dual-component Sulphate Solution Containing Nickel Ions,"J.
Membrane Sci., 146, 159-168 (1998) ; Q. M. Li, Q. Liu, Q. F. Zhang, X. J. Wei, and J. Z. Guo,"Separation Study of Cadmium through an Emulsion Liquid Membrane Using Triisooctylamine as Mobile Carrier,"Talanta, 46, 927-932 (1998) ; S. Y. B.
Hu and J. M. Wiencek,"Emulsion-Liquid-Membrane Extraction of Copper Using a Hollow-Fiber Contactor,"AIChE J., 570-581 (1998)).
The use of ELMs to remove radionuclides from aqueous feed solutions has also been long pursued in the scientific and industrial community. The ELMs for the removal of radionuclides, including strontium, cesium, technetium, and uranium, have been described in detail (W. S. Winston Ho and Kamalesh K. Sirkar, eds., Membrane Handbook, Chapman & Hall, New York, 1992). The extraction of strontium with the ELM technique has been investigated (I. Eroglu, R., Kalpakci, and G. Gunduz,"Extraction of Strontium Ions with Emulsion Liquid Membrane Technique", J. Membrane Sci., 80, 319-325 (1993)).
The use of ELMs to remove penicillin and organic acids from aqueous feed solutions has long been pursued in the scientific and industrial community. The use of ELMs for the extraction of Penicillin G from aqueous feed solutions has been described (T. Scheper, Z. Likidis, K. Makryaleas, Ch. Nowattny, and K. Schugerl, "Three Different Examples of Enzymatic Bioconversion in Liquid Membrane Reactors', Enzyme Microb. Technol., 9, 625-631 (1987) ; K. H. Lee, S. C. Lee, and W. K. Lee,"Penicillin G Extraction from Model Media Using an Emulsion Liquid Membrane : A Theoretical Model of Product Decomposition", J. Chem. Technol.
Biotechnol., 59, 365-370 (1994) ; K. H. Lee, S. C. Lee, and W. K. Lee,"Penicillin G
Extraction from Model Media Using an Emulsion Liquid Membrane : Determination of Optimum Extraction Conditions, J. Chem. Technol. Biotechnol., 59, 371-376 (1994) ; Y. S. Mok, S. C. Lee, and W. K. Lee,"Synergistic Effect of Surfactant on Transport Rate of Organic Acid in Liquid Emulsion Membranes", Sep. Sci.
Technol., 30, 399-417 (1995) ; S. C. Lee, K. H. Lee, G. H. Hyun, and W. K. Lee, "Continuous Extraction of Penicillin G by an Emulsion Liquid Membrane in a Countercurrent Extraction Column", J. Membrane Sci., 124, 43-51 (1997) ; S. C.
Lee, J. H. Chang, B. S. Ahn, and W. K. Lee,"Mathematical Modeling of Penicillin G Extraction in an Emulsion Liquid Membrane System Containing only a Surfactant in the Membrane Phase", J. Membrane Sci., 149, 39-49 (1998) ; S. C. Lee,"Effect of Volume Ratio of Internal Aqueous Phase to Organic Membrane Phase (W/O Ratio) of Water-in-Oil Emulsion on Penicillin G Extraction by Emulsion Liquid Membrane", J. Membrane Sci., 163, 193-201 (1999)).
The extraction of organic acids, including phenylalanine, acrylic acid, lactic acid, proprionic acid, citric acid, and acetic acid, from aqueous solutions with ELMs has been investigated (M. P. Thien and T. A. Hatton,"Liquid Emulsion Membranes and Their Applications in Biochemical Processing", Sep. Sci. Technol., 23, 819-853 (1988) ; D. J. O'Brien and G. E. Senske,"Separation and Recovery of Low Molecular Weight Organic Acids by Emulsion Liquid Membranes", Sep. Sci.
Technol., 24, 617-628 (1989) ; H. Itoh, M. P. Thien, T. A. Hatton, and D. I. C.
Wang,"Water Transport Mechanism in Liquid Emulsion Membrane Process for the Separation of Amino Acids", J. Membrane Sci., 51, 309-322 (1990) ; T. Hano, M.
Matsumoto, T. Kawazu, and T. Ohtake,"Separation of Di-and Tripeptides with Solvent Extraction and an Emulsion Liquid Membrane", J. Chem. Technol.
Biotechnol., 62, 60-63 (1995) ; P. J. Pickering and J. B. Chaudhuri,"Enantioselective Extraction of D-Phenylalanine from Racemic D-and L-Phenylalanine Using Chiral
Emulsion Liquid Membranes", J. Membrane Sci., 127, 115-130 (1997) ; M.
Matsumoto, T. Ohtake, M. Hirata, and T. Hano,"Extraction Rates of Amino Acids by an Emulsion Liquid Membrane with Tri-n-octylmethylammonium Chloride", J.
Chem. Technol. Biotechnol., 73, 237-242 (1998) ; X. R. Liu and D. S. Liu, "Modeling of Facilitated Transport of Phenylalanine by Emulsion Liquid Membranes with Di (2-ethylhexyl) Phosphoric Acid as a Carrier", Sep. Sci.
Technol., 33, 2597-2608 (1998)).
One disadvantage of ELMs is that the emulsion swells upon prolonged contact with the feed stream. This swelling causes a reduction in the stripping reagent concentration in the aqueous droplets which reduces stripping efficiency. It also results in dilution of the target species that has been concentrated in the aqueous droplets, resulting in lower separation efficiency of the membrane. The swelling further results in a reduction in membrane stability by making the membrane thinner. Finally, swelling of the emulsion increases the viscosity of the spent emulsion, making it more difficult to demulsify. A second disadvantage of ELMs is membrane rupture, resulting in leakage of the contents of the aqueous droplets into the feed stream and a concomitant reduction of separation efficiency. Raghuraman and Wiencek (B. Raghuraman and J. Wiencek,"Extraction with Emulsion Liquid Membranes in a Hollow-Fiber Contactor", AIChE J., 39, 1885-1889 (1993)) have described the use of microporous hollow-fiber contactors as an alternative contacting method to direct dispersion of ELMs to minimize the membrane swelling and leakage. This is due to the fact that the hollow-fiber contactors do not have the high shear rates typically encountered with the agitators used in the direct dispersion. Additional disadvantages include the necessary process steps for making and breaking the emulsion.
Thus, there is a need in the art for an extraction process which maximizes the stability of the SLM membrane, resulting in efficient removal and recovery of one or more target species from the aqueous feed solutions.
There is also a need in the art for an extraction process which maximizes the stability of the SLM membrane, resulting in efficient removal and recovery of one or more metals from the aqueous feed solutions.
There is a need in the art for an extraction process which maximizes the stability of the SLM membrane, resulting in efficient removal and recovery of one or more radionuclides from the aqueous feed solutions.
Further, there is a need in the art for an extraction process which maximizes the stability of the SLM membrane, resulting in efficient removal and recovery of penicillin from the aqueous feed solutions.
There is also a need in the art for an extraction process which maximizes the stability of the SLM membrane, resulting in efficient removal and recovery of one or more organic acids from the aqueous feed solutions.
Additionally, there is also a need in the art for extractants which selectively remove a given target species from the feed stream.
SUMMARY OF THE INVENTION The present invention relates generally to a process for the removal and recovery of target species from a feed solution using a combined SLM/strip dispersion. The invention also relates to a new family of extractants that are useful for the removal and recovery of such target species.
In one embodiment, the present invention relates to a process for the removal and recovery of one or more metals from a feed solution which comprises the following steps. First, a feed solution containing one or more metals is passed on one side of the SLM embedded in a microporous support material and treated to remove the metals by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion, is allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated metal solution.
In another embodiment, the present invention relates to a process for the removal and recovery of one or more radionuclides from a feed solution which comprises the following steps. First, a feed solution containing one or more radionuclides is passed on one side of the SLM embedded in a microporous support material and treated to remove the radionuclides by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion, is allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated radionuclide solution.
In yet another embodiment, the present invention relates to a process for the removal and recovery of penicillins and organic acids from a feed solution which comprises the following steps. First, a feed solution containing penicillin or organic acids is passed on one side of the SLM embedded in a microporous support material to remove the penicillin or organic acids by the use of a strip dispersion on the other
side of the SLM. As described above, the strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer.
The strip dispersion, or a part of the strip dispersion, is then allowed to stand, resulting in separation into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated solution of the target species. It must be noted that, as used in this specification and the appended claims, the term penicillin shall be inclusive of all members of the group of antibiotics biosynthesized by several species of molds and any synthetic derivatives.
In these and other embodiments, the continuous organic phase of the strip dispersion readily wets the pores of a microporous support to form a stable SLM.
The process of the present invention provides a number of operational and economic advantages over the use of conventional SLMs.
In a further embodiment, the present invention relates to an SLM embedded in a microporous support material having an interfacial polymerized layer or layers.
In another embodiment, the present invention relates to a process for the removal and recovery of one or more target species, such as metals, radionuclides, penicillins, and organic acids, from a feed solution which comprises the following steps. First, a feed solution containing one or more of the target species is passed on one side of the SLM embedded in a microporous support material with an interfacial polymerized layer or layers to remove the target species by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer.
The strip dispersion, or a part of the strip dispersion, is then allowed to stand, resulting in separation into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated solution of the target species.
In these and other embodiments, the continuous organic phase of the strip dispersion readily wets the pores of a microporous support to form a stable SLM.
The process of the present invention provides a number of operational and economic advantages over the use of conventional SLMs.
In yet another embodiment, the present invention relates to a family of new extractants, alkyl phenylphosphonic acids, e. g., 2-butyl-l-octyl phenylphosphonic acid (BOPPA) and 2-octyl-l-dodecyl phenylphosphonic acid (C20 ODPPA), which are useful in both conventional SLMs and the process of the present invention for the removal and recovery of radionuclide and/or metal species, also called herein the "target species."Use of the new extractants result in improved extraction and an increased concentration of the target species in the aqueous strip solution. The invention also relates to a method for the production of these alkyl phenylphosphonic acids.
In yet another embodiment, the invention relates to new class of extractants that include dialkyl phosphoric acids containing alkyl chains of at least 8 to 12 carbon atoms. The compound di (2-butyloctyl) monothiophosphoric acid (C12 MTPA) is particularly useful for the removal and recovery of nickel. The invention also relates to a method for the production of these dialkyl phosphoric acids.
Thus, it is an object of the invention to provide a process for the removal and recovery of target species from a feed solution using a combined SLM/strip dispersion method.
It is another object of the present invention to provide a process for the removal and recovery of target species which provides increased membrane stability.
It is yet another object of the present invention to provide a process having improved flux.
It is a further object of the present invention to provide a process having improved recovery of the target species to provide a concentrated strip solution.
It is yet another object of the invention to provide a process for the removal and recovery of a target species from a feed solution which exhibits decreased operation costs and a decreased capital investment over convention SLM processes.
It is an object of the present invention to provide a process for the removal and recovery of one or more metals from a feed solution.
It is another object of the present invention to provide a process for the removal and recovery of cobalt, copper, zinc, nickel, mercury, lead, cadmium, silver, europium, lanthanum, neodymium, praseodymium, gadolinium, and selenium from a feed solution.
It is a yet another object of the invention to provide a process for the removal and recovery of calcium, magnesium, and/or zinc from a feed solution.
It is a further object of the present invention to provide a process for the removal and recovery of radionuclides from a feed solution.
It is an object of the present invention to provide a process for the removal and recovery of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, or americium from a feed solution.
It is another object of the present invention to provide a process for the removal and recovery of penicillins from a feed solution.
It is yet another object of the present invention to provide a process for the removal and recovery of penicillin G and penicillin V from a feed solution.
It is a further object of the present invention to provide a process for the removal and recovery of organic acids.
It is an object of the present invention to provide a process for the removal and recovery of phenylalanine, acrylic acid, lactic acid, proprionic acid, and acetic acid from a feed solution.
It is another object of the present invention to provide an SLM, embedded in a microporous support material with an interfacial polymerized layer or layers.
It is also an object of the present invention to provide a process for the removal and recovery of metals, radionuclides, penicillins, and organic acids from a feed solution with an SLM, embedded in a microporous support material with an interfacial polymerized layer or layers.
It is yet another object of the invention to provide a family of new extractants, alkyl phenylphosphonic acids, for the removal of target species.
It is an object of the invention to provide the compound 2-butyl-l-octyl phenylphosphonic acid (BOPPA) for the removal of target species.
It is another object of the invention to provide the compound 2-octyl-1- dodecyl phenylphosphonic acid (C20 ODPPA) for the removal of target species.
It is yet another object of the invention to provide a process for the removal of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, or americium using an alkyl phenylphosphonic acid.
It is a further object of the invention to provide a process for the removal of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, or americium using 2-butyl-1-octyl phenylphosphonic acid (BOPPA).
It is an object of the invention to provide a process for the removal of strontium, cesium, technetium, uranium, boron, plutonium, cobalt, or americium using 2-octyl-1-dodecyl phenylphosphonic acid (C20 ODPPA).
It is another object of the invention to provide a process for the removal of calcium, magnesium, and/or zinc using an alkyl phenylphosphonic acid.
It is yet another object of the invention to provide a process for the removal of calcium, magnesium, and/or zinc using 2-butyl-l-octyl phenylphosphonic acid (BOPPA).
It is a further object of the invention to provide a process for the removal of calcium, magnesium, and/or zinc using 2-octyl-l-dodecyl phenylphosphonic acid (C20 ODPPA).
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of the combined supported liquid membrane/strip dispersion of the present invention.
Figure 2 is an enlarged view of the schematic representation of the combined supported liquid membrane/strip dispersion of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a process for the removal and recovery of a target species from a feed solution, such as waste waters or process streams. This new process employs a combination of a supported liquid membrane (SLM) and a strip dispersion.
In one embodiment of the present invention, the target species is a metal.
Preferred metal species include, but are not limited to, cobalt, copper, zinc, nickel, mercury, lead, cadmium, silver, europium, lanthanum, neodymium, praseodymium, gadolinium, and selenium. Other preferred metals include calcium, magnesium, and zinc. The process of the invention comprises the following steps. First, a feed solution containing one or more metals is passed on one side of the SLM embedded in a microporous support material and treated to remove the metal or metals by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion is allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated metal solution.
In another embodiment of the present invention, the target species is a radionuclide. Preferred radionuclide species include, but are not limited to, strontium, cesium, technetium, uranium, boron, plutonium, cobalt, and americium.
The process of the invention comprises the following steps. First, a feed solution containing one or more radionuclides is passed on one side of the SLM embedded in a microporous support material and treated to remove the radionuclide or radionuclides by the use of a strip dispersion on the other side of the SLM. The strip
dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion is allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated radionuclide solution.
In yet another embodiment of the present invention, the target species is a penicillin. Preferred penicillin species include, but are not limited to, penicillin G and penicillin V. The process of the invention comprises the following steps. First, a feed solution containing one or more penicillins is passed on one side of the SLM embedded in a microporous support material and treated to remove the penicillin by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion is allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated penicillin solution.
In another embodiment of the present invention, the target species is an organic acid. Preferred organic acid species include, but are not limited to, phenylalanine, acrylic acid, lactic acid, proprionic acid, citric acid, and acetic acid.
The process of the invention comprises the following steps. First, a feed solution containing one or more organic acids is passed on one side of the SLM embedded in a microporous support material and treated to remove the organic acid or acids by the use of a strip dispersion on the other side of the SLM. The strip dispersion can be formed by dispersing an aqueous strip solution in an organic liquid, for example, using a mixer. Second, the strip dispersion, or a part of the strip dispersion is
allowed to stand, resulting in separation of the dispersion into two phases : the organic liquid phase and the aqueous strip solution phase containing a concentrated organic acid solution.
While any SLM configuration may be employed in the process of the invention, the preferred configuration employs a hollow fiber module as the liquid membrane microporous support. Such hollow fiber modules consist of microporous hollow fibers arranged in a shell-and-tube configuration. In the present invention, the strip dispersion is passed through either the shell side of the module or the tube side of the module, and the aqueous feed solution containing the target species for extraction is passed through the opposing side of the module. The use of the hollow fiber system in the combined SLM/strip dispersion process allows continuous replenishment of the strip dispersion as shown in Figure 1, ensuring a stable and continuous operation.
For the purposes of the invention, strip dispersion is defined as a mixture of an aqueous phase and an organic phase. The aqueous phase of the dispersion comprises an aqueous strip solution, while the organic phase comprises an extractant or extractants in an organic liquid. The dispersion is formed by the mixing of the aqueous and organic phases as shown in Figure 1. This combination results in droplets of the aqueous strip solution in a continuous organic phase. The dispersion is maintained during the extraction process due to the flow of the dispersion through a membrane module, e. g., a hollow fiber module. The continuous organic phase of the strip dispersion readily wets the hydrophobic pores of the microporous hollow fibers in the module, forming a stable liquid membrane.
Figure 2 shows an enlarged view of a schematic representation of the SLM with strip dispersion of the present invention. A low pressure, Pa, which is typically
less than approximately 2 psi, is applied on the feed solution side of the SLM. The pressure Pa is greater than the pressure, POS on the strip dispersion side of the SLM.
This difference in pressure prevents the organic solution of the strip dispersion from passing through the pores to come into the feed solution side. The dispersed droplets of the aqueous strip solution have a typical size of about 80 to about 800 micrometers and are orders of magnitude larger than the pore size of the microporous support employed for the SLM, which is in the order of approximately 0. 03 micrometer. Thus, these droplets are retained on the strip dispersion side of the SLM and cannot pass through the pores to go to the feed solution side.
In this SLM/strip dispersion system, there is a constant supply of the organic membrane solution, i. e. the organic phase of the strip dispersion, into the pores.
This constant supply of the organic phase ensures a stable and continuous operation of the SLM. In addition, the direct contact between the organic and strip phases provides efficient mass transfer for stripping. The organic and strip phases can be mixed, for example, with high-shear mixing to increase the contact between the two phases.
Once removal of the target species is complete, the mixer for the strip dispersion is stopped, and the dispersion is allowed to stand until it separates into two phases, the organic membrane solution and the concentrated strip solution. The concentrated strip solution is the product of this process.
The feed solution includes, but is not limited to, waste waters or process streams containing metals. The metals include, but are not limited to, cobalt, copper, zinc, nickel, mercury, lead, cadmium, silver, europium, lanthanum, neodymium, praseodymium, gadolinium, chromium, calcium, magnesium, and selenium. The radionuclides include, but are not limited to, strontium, cesium,
technetium, uranium, boron, plutonium, cobalt, and americium. The penicillins include, but are not limited to, penicillin G and penicillin V. The organic acids include, but are not limited to phenylalanine, acrylic acid, lactic acid, proprionic acid, and acetic acid.
The microporous support employed in the invention is comprised of, for example, microporous polypropylene, polytetrafluoroethylene, polyethylene, polysulfone, polyethersulfone, polyetheretherketone, polyimide, polyamide, or mixtures thereof. The preferred microporous support is microporous polypropylene hollow fibers.
The aqueous portion of the strip dispersion comprises an aqueous acid solution or an aqueous base solution. For the removal or metals or radionuclides, the aqueous portion of the strip dispersion comprises an aqueous acid solution, such as a mineral acid. Examples of acids useful in the present invention include, but are not limited to, sulfuric acid (H2SO4), hydrochloric acid (HCl), nitric acid (HNO3), phosphoric acid (H3PO4), and acetic acid (CH3COOH). The acid is present in a concentration between about 0. 1 M and about 18 M. The preferred concentration for the acid solution is between about 1 M and about 3 M.
For the removal or penicillins or organic acids, the aqueous portion of the strip dispersion comprises an aqueous base solution. Examples of bases useful in the present invention include, but are not limited to, sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), ammonium hydroxide (NH40H), and tetramethylammonium hydroxide ((CH) 4NOH). The base is advantageously present in a concentration between about 0. 01 M and about 16 M, more preferably between about 0. 2 M and about 2M.
The continuous organic liquid phase into which the aqueous strip solution is dispersed contains an extractant or extractants. Any extractant capable of extracting the target species contained in the feed solution can be used in the present invention.
Typical extractants which are known in the art for extraction of species from waste waters or process streams may be employed in the present strip dispersion. Some nonlimiting examples of such extractants include, di (2, 4, 4- trimethylpentyl) dithiophosphonic acid), a nonylsalicyl aldoxime and ketoxime extractant system 9 e. g., LIX 973N containing about 46% nonylsalicyl aldoxime, 18% ketoxime, 6% nonylphenol, and 30% diluent), di (2-ethylhexyl) phosphoric acid (D2EHPA), oleic acid, and those disclosed in the references listed in the background ssection. Selection of such extractants based upon the specific target species to be extracted is within the level of skill in the art. In addition to conventional extractants, any other extractant that will extract the metal, radionuclide, penicillin, or organic acid species contained in the feed solution can be employed in the present invention.
The present invention also comprises a new families of extractants. One of these families of extractants are alkyl phenylphosphonic acids. These alkyl phenylphosphonic acids have advantageous properties over prior art extractants.
The alkyl group of the alkyl phenylphosphonic acid is paraffinic (saturated) and includes from 6 to 26 carbon atoms. The new alkyl phenylphosphonic acids include 2-butyl-l-octyl phenylphosphonic acid (BOPPA ; C12 alkyl group), 2-hexyl-l-decyl phenylphosphonic acid (C16 alkyl group), 2-octyl-1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid (C18 alkyl group), 2-octyl-1-dodecyl phenylphosphonic acid (C20 ODPPA ; C20 alkyl group), hexyl phenylphosphonic acid (C6 alkyl group), heptyl phenylphosphonic acid (C7 alkyl group), octyl phenylphosphonic acid (C8 alkyl group), nonyl phenylphosphonic acid (C9 alkyl group), decyl
phenylphosphonic acid (C 10 alkyl group), undecyl phenylphosphonic acid (C 11 alkyl group), dodecyl phenylphosphonic acid (C 12 alkyl group), tridecyl phenylphosphonic acid (C 13 alkyl group), tetradecyl phenylphosphonic acid (C14 alkyl group), pentadecyl phenylphosphonic acid (C15 alkyl group), hexadecyl phenylphosphonic acid (C16 alkyl group), heptadecyl phenylphosphonic acid (C17 alkyl group), octadecyl phenylphosphonic acid (C18 alkyl group), nonadecyl phenylphosphonic acid (C19 alkyl group), decadecyl phenylphosphonic acid (C20 alkyl group), undecadecyl phenylphosphonic acid (C21 alkyl group), dodecadecyl phenylphosphonic acid (C23 alkyl group), tridecadecyl phenylphosphonic acid (C23 alkyl group), tetrdecadecyl phenylphosphonic acid (C24 alkyl group), pentadadecyl phenylphosphonic acid (C25 alkyl group), hexadecadecyl phenylphosphonic acid (C26 alkyl group), and mixtures thereof. Preferred alkyl phenylphosphonic acids include BOPPA and (C20 ODPPA).
The new extractants are useful for the removal and recovery of radionuclides, such as strontium, cesium, plutonium, cobalt, and americium, and metal species, such as calcium, magnesium, and zinc. In a preferred embodiment, the alkyl phenylphosphonic acid is employed as the extractant in the strip dispersion in the process of the invention. As seen from the examples appended below, the alkyl phenylphosphonic acid has significantly increases the extraction of strontium from feed solutions. The new extractant also extends the SLM operation to a lower pH range to better utilize the available surface area of the hollow-fiber module. For example, for the removal of strontium, the pH has been reduced from 4. 5 to 3.
The alkyl phenylphosphonic acid may be synthesized, for example, by reacting an alcohol containing from 6 to 26 carbon atoms and phenylphosphonyl dichloride in an organic solvent, such as pyridine. Preferred temperatures for the
reaction are between about 0 and 10°C. The reaction is quenched by adding concentrated HCl and ice to the reaction mixture, resulting in a solution having a pH of 1. The alkyl phenylphosphonic acid can then be extracted from the reaction mixture using a solvent, such as toluene. The alkyl phenylphosphonic acid/solvent solution was washed with 1 M HCl solution and dried, for example, with MgSO4 to produce a clear solution. The alkyl phenylphosphonic acid can then be recovered by evaporating the solvent from the solution in any manner.
BOPPA may be synthesized, for example, by reacting 2-butyl-l-octanol and phenylphosphonyl dichloride in an organic solvent. Preferred temperatures for the reaction are between about 0 and 10°C. The reaction is quenched by adding concentrated HCl and ice to the reaction mixture, resulting in a solution having a pH of 1. The BOPPA can then be extracted from the reaction mixture using a solvent, such as toluene. The BOPPA/solvent solution was washed with 1 M HCl solution and dried, for example, with MgSO4 to produce a clear solution. The BOPPA can then be recovered by evaporating the solvent from the solution in any manner. The other alkyl phenylphosphonic acids, including 2-hexyl-l-decyl (C16) phenylphosphonic acid, 2-octyl-1-decyl/2-hexyl-1-dodecyl (C18) phenylphosphonic acid, 2-octyl-l-dodecyl (C20) phenylphosphonic acid, can be synthesized in a similar manner.
The present invention also comprises another family of novel extractants.
This new class of extractants include dialkyl phosphoric acids containing alkyl chains of at least 8 to 12 carbon atoms. The compound di (2- butyloctyl) monothiophosphoric acid (C12 MTPA) is particularly useful for the removal and recovery of nickel.
These dialkyl monothiophosphoric acids can be produced, for example, by the following process. In general, the process involves reacting phosphorus pentasulfide (P2Ss) with an alcohol under heat to provide multiple alkyl thiophosphate intermediates. These intermediates are then hydrolyzed, for example, with mineral acids, to the dialkyl monothiophosphoric acid that corresponds to the alcohol used. the method can be carried out as a two-step synthesis, and can conveniently be performed in a single reaction vessel. A solvent, such as toluene or other hydrocarbon solvents, can optionally be employed in the reaction of the phosphorus pentasulfide and alcohol ; however, use of a solvent is not necessary.
The hydrolysis reaction can be monitored, for example by fourier transfer infrared (FTIR) spectrometer, to determine when to stop the reaction. by-products of the reaction, such as phosphoric acid and residual alcohols, are easily removed. The phosphoric acid formed during the process can be removed, for example, by washing the final reaction mixture with water. After completion of the hydrolysis, any residual alcohol can be separated from the monothiophosphates, for example, by distillation under vacuum.
The process can conveniently be depicted by the following reaction scheme : (1) 3P2S5 +12ROH => 2 (RO) 3P (S) + 2 (RO) 2P (S) SH + 2 (RO) P (S) (SH) 2+ H3PS03 (2) (RO) 2P (S) SH + H+ > (R0) 2P (S) OH + H2 S where R= alkyl chains of 8 to 12 carbon atoms.
Alcohols that can be used in the present process include, but are not limited to, 2-ethyl-l-hexanol (C8) ; 3, 5, 5-trimethyl-l-hexanol (C9) ; 3, 7-dimethyl-l-octanol (C10) ; and 2-butyl-l-octanol (C12). A preferred alcohol is 2-butyl-l-octanol.
Dialkyl monothiophosphoric acids that can be produced by the process include, but are not limited to, di (2-ethylhexyl) monothiophosphoric acid ; di (3, 5, 5- trimethylhexyl) monothiophosphoric acid ; di (3, 7-dimethyloctyl) monothiophosphoric acid ; and di (2-butyloctyl) monothiophosphoric acid. A preferred monothiophosphoric acid is di (2-butyloctyl) monothiophosphoric acid.
Mineral acids which can be used to hydrolyze the P2S5 include, but are not limited to, sulfuric acid (H2 S04), nitric acid (HNO3), and hydrochloric acid (HCl), with about 2 normal to about 4 normal HCl being preferred.
Solvents that can be used in the process include but are not limited to toluene, benzene, p-xylene, and m-xylene. Toluene is the preferred solvent, however, it is not necessary to use a solvent for dissolving the P2Ss in the present invention.
In step (1) of the process, the reaction mixture can be heated. advantageously, the reaction mixture can be heated to a temperature in the range of about 60°C to about 160°C for a period of about 1 hour to about 60 hours.
Preferably, the reaction mixture is heated to a temperature from about 70°C to about 145°C for a period of about 1 to about 24 hours, more preferably to a temperature from about 80°C to about 100°C for a period from about 4 hours to about 6 hours.
In step (2) of the process, the hydrolysis reaction can be heated.
Advantageously, the reaction can be heated to a temperature in the range of about 60°C to about 120° for a period of about 1 hour to about 10 hours. Preferred reaction parameters include either heating to a temperature of about 80°C to about 100°C for a period of about 6 hours to about 8 hours, or to a temperature of about 100°C to about 120°C for about 3 hours to about 4 hours.
The process of the present invention is similar to the reaction of phosphorous pentoxide (P2 Os) with alcohol. However, the use of phosphorus pentasulfide P2S5 has several advantages. First, the addition of phosphorus pentasulfide (P2Ss) to alcohols is less critical to the reaction than the addition of alcohols to phosphorous pentoxide (P2Os), since the reaction rates for Puss are slower, and phosphorus pentasulfide is the limiting reagent. Second, it is not necessary to use a solvent, rather the P2Ss can be dissolved directly into the alcohol. Another advantage of the present process is that the reagents are non-toxic and easy to handle, making the process practical for industrial scale-up.
The organic liquid of the present strip dispersion optionally comprises a hydrocarbon solvent or mixture. The hydrocarbon solvent or mixture has a number of carbon atoms per solvent molecule ranging from 6 to 18, preferably from 10 to 14. Hydrocarbon solvents that are useful in the present invention include, but are not limited to, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isoparaffinic hydrocarbon solvent (with a flash point of 92°C, a boiling point of 254°C, a viscosity of 3 cp (at 25°C), and a density of 0. 791 g/ml (at 15. 6°C) or mixtures thereof.
The organic liquid of the present strip dispersion optionally comprises a modifier to enhance the complexation and/or stripping of the target species. The modifier can be, for example, an alcohol, a nitrophenyl alkyl ether, a trialkyl phosphate or mixtures thereof. Examples of alcohols that can be used in the present invention include, but are not limited to, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol or mixtures thereof. The nitrophenyl ether can be, for
example, o-nitrophenyl octyl ether (o-NPOE), o-nitrophenyl heptyl ether, o- nitrophenyl hexyl ether, o-nitrophenyl pentyl ether (o-NPPE), o-nitrophenyl butyl ether, o-nitrophenyl propyl ether or mixtures thereof. The trialkyl phosphate can be, for example, tributyl phosphate, tris (2-ethylhexyl) phosphate or mixtures thereof.
The above lists of modifiers are nonlimiting examples of modifiers that can be used in the present invention. Other similar modifiers as will be appreciated by those skilled in the art can also be employed as modifiers in the present invention.
The organic liquid of the present strip dispersion comprises about 2%- 100% (approximately 0. 05M-3M) extractant and about 0%-20% modifier in a hydrocarbon solvent or mixture. More preferably, the organic liquid of the present strip dispersion comprises about 5%-40% extractant and about 1%-10% modifier in a hydrocarbon solvent or mixture. Even more preferably, the organic liquid comprises about 5%-40% extractant and about 1%-10% dodecanol in an isoparaffinic hydrocarbon solvent or in n-dodecane. All percentages are by weight unless specified otherwise.
The present invention has several advantages over conventional SLM technology. These advantages include increased membrane stability, reduced costs, increased simplicity of operation, improved flux, and improved recovery of target species concentration. These advantages also include increased simplicity of operation, reduction of capital and operation costs, and increased efficiency of target species removal.
The present invention provides a constant supply of the organic membrane solution into the pores of the hollow fiber support. This constant supply results in an SLM which is more stable than conventional SLMs, ensuring stable and continuous operation. This constant supply also eliminates the need for recharging
membrane modules, which is required with conventional SLMs. It further eliminates the need for a second set of membrane modules for use during recharging of the first set of membrane modules. Thus, the present invention decreases not only operational costs but also the initial capital investment in the system. The present invention also increases simplicity of the removal operation.
The present invention provides direct contact between the organic/extraction phase and aqueous strip phase. Mixing of these phases provides an extra mass transfer surface area in addition to the area given by the hollow fibers, leading to extremely efficient stripping of the target species from the organic phase. This efficient stripping enhances the flux for the extraction of many targeted species. For example, fluxes of about 3 g/(m2*hr) or higher for treatment of the feed solution are typical for the present invention. In fact, unexpectedly high flux results with the present invention as compared to those observed with conventional SLM separation processes. Particularly advantageous fluxes result with the present process when it is used for the removal and recovery of cobalt.
The present invention comprises a new type of SLM which provides increased flexibility of aqueous strip/organic volume ratio. This flexibility allows the use of a smaller volume of aqueous strip solution to obtain a higher concentration of the recovered target species in the aqueous strip solution. The concentrated strip solution is a valuable product for resale or reuse.
This invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof. To the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without
departing from the spirit of the present invention and/or the scope of the appended claims.
EXAMPLES GENERAL PROCEDURE FOR EXAMPLES 1 TO 33 The strip dispersion for each of the following examples was prepared by mixing an aqueous strip solution in a quantity of, for example, 200 ml, and an organic extractant solution (for example, dodecane containing 2 wt. % dodecanol and 8 wt. % extractant) in a quantity of, for example, 600 ml, in a Fisher brand mixer with a 2-inch diameter, 6-bladed, high-shear impeller at 500 rpm as measured by an Ono Sokki HT-4100 tachometer. The mixer was plugged into a varistat to allow for adjustable speed control. The impeller was initially started at 50% of its full power and the varistat at 80%.
All of the following examples were run in countercurrent fashion with the feed solution passed through the tube side of the microporous polypropylene hollow fiber module. The hollow-fiber moldule was 2. 5 inches in diameter and 8 inches in length, providing a surface area of 1. 4 m2. The process was first started by passing water through the hollow fiber module. The pressures were adjusted to provide a positive pressure on the feed side of the hollow fiber module. Once the pressures were adjusted and stable, the water was replaced with the feed solution. A positive pressure was maintained on the feed side to prevent the organic phase in the shell side from passing through the pores of the hollow fibers.
The pressure of the inlet on the shell side was maintained at 1. 25 psi and the outlet pressure of the feed side was set at 3. 25 psi, thus maintaining a 2 psi differential between the two sides. In each of the runs, the feed flow was adjusted to
give a flow rate of approximately 0. 84 liter/min at these pressures. The typical feed solution volume for these experiments was 4 liters.
Samples from the feed solution and the strip dispersion were taken at timed intervals. The strip dispersion samples were allowed to stand until phase separation occurred. The aqueous phase from the strip dispersion sample was then collected and centrifuged to facilitate complete separation. The aqueous phase samples from the strip dispersion samples and the feed solution samples were then analyzed by inductively coupled plasma (ICP) spectrometry.
The flux of a species removed from the feed solution can be defined by the following formula : V AC flux = t A where V is the volume of the feed solution treated ; AC is the concentration change in the feed solution ; t is the time at which the sample was taken ; and A is the membrane surface area. The flux of the species was calculated from the above equation.
The mass transfer coefficient k of the species removed from the feed solution can be defined by the following formula :
v C. k=-----In(--) t A Ct where C. is the initial concentration of the species in the feed solution ; C, is the concentration of the species in the feed solution at time t ; t is the time ; and the rest of the symbols are as defined above. The mass transfer coefficient k of the species was calculated from the above equation.
EXAMPLE 1 UNEXPECTEDLY HIGH FLUX RESULTS FOR COBALT A fresh solution of 2. 5 M His04 was prepared for use as the strip solution.
A strip dispersion was then prepared by mixing together 200 ml of the 2. 5 M H2SO4 solution and 600 ml of an organic solution containing 24 wt. % di (2, 4, 4- trimethylpentyl) dithiophosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol, and 74 wt. % Isopar L as described in the general procedure above. This strip dispersion was then fed into the shell side of a 2. 5-inch diameter polypropylene hollow fiber module (2. 5 inches in diameter by 8 inches in length). A feed solution containing a cobalt concentration of 489 parts per million (ppm) was passed into the tube side of the hollow fiber module. The pH of the feed solution was maintained at 2. 3 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 1 below.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 8. 777 g/(m2*hr) at a cobalt concentration of 233 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under similar conditions with the conventional SLM as described in Example 3. The fluxes for the latter, even at the higher cobalt concentrations of 358 ppm and 272 ppm in the feed solution, were only 1. 954 and 1. 474 g/(m2*hr), respectively. Thus, cobalt flux with the present invention was more than 4. 5 times higher than that with conventional SLM.
In addition, the extractant concentration of 24 wt. % was much lower than the extractant concentration for the conventional SLM in Example 3 which was about 37 wt. %. In general, a higher extractant concentration should give a higher flux. Thus, the high flux of the seen with the present invention was an unexpected result.
Table 1
EXAMPLE 2 UNEXPECTEDLY HIGH FLUX RESULTS FOR COBALT The experimental procedure for this example was the same as that described in Example 1, except that a feed solution containing 571 ppm cobalt and the used strip dispersion from the preceding example were employed. The excess aqueous strip and organic solutions from the strip dispersion samples from the preceding example were returned to the strip dispersion tank before the start of this experiment. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 2.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 10. 217 g/(m2*hr) at the cobalt concentration of 273 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The fluxes for the latter, even at a higher cobalt concentration of 358 ppm and a similar cobalt concentration of 272 ppm in the feed solution, were only 1. 954 and 1. 474 g/(m2*hr), respectively. Thus, the cobalt flux with the present invention was more than 5. 2 times higher than that with the conventional SLM. In addition, the extractant concentration of 24 wt. % was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux.
Again, the high flux was an unexpected result of the present invention.
Table 2
EXAMPLE 3 COMPARATIVE EXAMPLE USING CONVENTIONAL SLM As described in the Background of the Invention, the organic membrane phase of the conventional SLM (imbedded in a microporous support) was placed between two aqueous solutions-the feed solution and a strip solution that was not a strip dispersion. The microporous support used for this example was the same type and same size of the hollow fiber module employed and described in Example 1.
The organic membrane solution was similar to that used in Example 1 except the concentration of the extractant, di (2, 4, 4-trimethylpentyl) dithiophosphinic acid (e. g., Cyanex 301), was higher, i. e., 1 M (approximately 37 wt. % instead of the 24 wt. % used in Example 1). In a manner similar to Example 1, a feed solution containing 472 ppm cobalt and a sulfuric acid strip solution were used in Example 3. In the same way as in Example 1, the pH of the feed solution was maintained by adding 5
M NaOH as needed. Also in a similar countercurrent flow configuration, the feed solution was passed into the tube side of the hollow fiber module, whereas the strip solution was fed into the shell side of the module. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 3.
As shown in Table 3, the cobalt fluxes at the cobalt concentrations of 358 ppm and 272 ppm in the feed solution were only 1. 954 and 1. 474 g/(m2*hr), respectively. These fluxes were much lower than those with the present invention described in Examples 1 and 2, in spite of much higher extractant concentrations. In general, a higher extractant concentration should give a higher flux. In other words, there were unexpected results with the present invention.
Table 3
EXAMPLE 4 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 2 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Example 1, except that a feed solution containing 562 ppm cobalt and an organic solution of the strip dispersion containing 8 wt. % di (2, 4, 4-trimethylpentyl) dithio- phosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol, and 90 wt. % Isopar L were used. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 4.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 7. 406 g/(m2*hr) at a cobalt concentration of 346 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter, even at a higher cobalt concentration of 358 ppm in the feed solution, was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was at least 3. 8 times higher than that with the conventional SLM. In addition, the extractant concentration of 8 wt. % for the present Example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux of the present invention was an unexpected result.
Table 4
EXAMPLE 5 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 2 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Example 4, except that a feed solution containing 567 ppm cobalt and the used strip dispersion from the Example 4 were used. The excess aqueous strip and organic solutions from the strip dispersion samples of Example 4 were returned to the strip dispersion tank before the start of the run for this experiment. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 5.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 8. 023 g/(m2*hr) at a cobalt
concentration of 333 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter, even at a higher cobalt concentration of 358 ppm in the feed solution, was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was more than 4. 1 times higher than that with the conventional SLM. In addition, the extractant concentration of 8 wt. % for the present Example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux was an unexpected result of the present invention.
Table 5
EXAMPLE 6 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 3 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Examples 1 and 4, except that a feed solution containing 562 ppm cobalt and an organic solution of the strip dispersion containing 8 wt. % di (2, 4, 4- trimethylpentyl) dithio-phosphinic acid (e. g., Cyanex 301), 3 wt. % dodecanol, and 89 wt. % Isopar L were used. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above.
Fluxes and k values were then calculated and are reported in Table 6.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 6. 960 g/(m2*hr) at the cobalt concentration of 359 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter at a similar cobalt concentration of 358 ppm in the feed solution was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was more than 3. 6 times higher than that with the conventional SLM. In addition, the extractant concentration of 8 wt. % for the present example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux was an unexpected result of the present invention.
Table 6
EXAMPLE 7 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 3 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Example 6, except that a feed solution containing 551 ppm cobalt and the used strip dispersion from Example 6 were employed. The excess aqueous strip and organic solutions from the strip dispersion samples from Example 6 were returned to the strip dispersion tank before the start of this experiment. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 7.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 6. 926 g/(m2*hr) at the cobalt
concentration of 349 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter, even at a higher cobalt concentration of 358 in the feed solution, was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was more than 3. 5 times higher than that with the conventional SLM. In addition, the extractant concentration of 8 wt. % for the present Example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux was an unexpected result of the present invention.
Examples 4-7 also served to investigate the effect of dodecanol concentration on cobalt flux. As shown in Table 7, the effect of dodecanol concentration on cobalt flux in these examples was not very significant for dodecanol concentrations of 2 wt. % and 3 wt. %.
Table 7
EXAMPLE 8 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 1 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Examples 1, 4, and 6, except that a feed solution containing 576 ppm cobalt and an organic solution of the strip dispersion containing 8 wt. % di (2, 4, 4- trimethylpentyl) dithio-phosphinic acid (e. g., Cyanex 301), 1 wt. % dodecanol, and 91 wt. % Isopar L were used. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above.
Fluxes and k values were then calculated and are reported in Table 8.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 6. 171 g/(m2*hr) at the cobalt concentration of 396 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter at a cobalt concentration of 358 ppm in the feed solution was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was about 3. 2 times higher than that with the conventional SLM.
In addition, the extractant concentration of 8 wt. % for this example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux was an unexpected result of the present invention.
Table 8
EXAMPLE 9 ORGANIC SOLUTION COMPRISING 8% EXTRACTANT AND 1 % DODECANOL FOR COBALT The experimental procedure for this example was the same as that described in Example 8, except that a feed solution containing 570 ppm cobalt and the used strip dispersion from Example 8 were employed. The excess aqueous strip and organic solutions from the strip dispersion samples from Example 8 were returned to the strip dispersion tank before the start of this experiment. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 9.
The cobalt was removed from the feed solution, concentrated, and recovered in the aqueous strip solution. The cobalt flux of 7. 269 g/ (mz*hr) at the cobalt
concentration of 358 ppm in the feed solution was unexpectedly high in comparison with the cobalt flux obtained under the similar conditions with the conventional SLM described in Example 3. The flux for the latter, even at the same cobalt concentration of 358 in the feed solution, was only 1. 954 g/(m2*hr). Thus, the cobalt flux with the present invention was more than 3. 7 times higher than that with the conventional SLM. In addition, the extractant concentration of 8 wt. % for the present example was much lower than that of about 37 wt. % for the conventional SLM in Example 3. As mentioned, a higher extractant concentration should generally give a higher flux. Again, the high flux was an unexpected result of the present invention.
Examples 4-9 also served to investigate the effect of the concentration of the modifier, dodecanol, on cobalt flux. As shown from these examples, the effect of dodecanol concentration on cobalt flux was not very significant for dodecanol concentrations ranging from 1 wt. % to 3 wt. %. In other words, dodecanol concentrations ranging from 1 wt. % to 3 wt. % were effective.
Table 9
EXAMPLE 10 COBALT REMOVED TO LOW CONCENTRATION IN TREATED FEED AND CONCENTRATED TO HIGH CONCENTRATION IN STRIP The experimental procedure for this example was the same as that described in Example 1, except that a 1-liter feed solution containing 524 ppm cobalt with pH 2 ; an 800-ml organic solution of 8 wt. % di (2, 4, 4-trimethylpentyl) dithiophosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol ; and 90 wt. % Isopar L, and a 60-ml strip solution of 5 M hydrochloric acid were used. The pH of the feed solution was maintained at 2. 0 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 10.
The cobalt concentration of the feed solution was changed from 524 ppm to 0. 7 ppm in just 15 minutes where the recycle mode of operation was used for both the feed solution and the strip dispersion. On the other hand, the cobalt was recovered and concentrated to about 30, 000 ppm in the aqueous strip solution at the same time.
Table 10
EXAMPLE 11 COBALT REMOVED FROM FEED AND CONCENTRATED TO VERY HIGH CONCENTRATION IN STRIP The experimental procedure for this example was the same as that described in Example 1, except that a 40-liter feed solution containing 492 ppm cobalt with pH 2 ; a 900-ml organic solution of 8 wt. % di (2, 4, 4-trimethylpentyl) dithiophosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol, and 90 wt. % Isopar L ; and a 105-ml strip solution of 6. 5 M hydrochloric acid were used. The pH of the feed solution was maintained at 2. 0 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed
and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 11.
The cobalt was removed from the feed solution, recovered, and concentrated to more than 96, 000 ppm in the aqueous strip solution in 6 hours using the recycle mode of operation for both the feed solution and the strip dispersion. The cobalt concentration in the strip solution was more than 195 times the original feed concentration.
Table 11
EXAMPLE 12 COPPER REMOVED TO LOW CONCENTRATION IN TREATED FEED AND CONCENTRATED TO HIGH CONCENTRATION IN STRIP The experimental procedure for this example was the same as that described in Example 1, except that a 5-liter feed solution containing 151 ppm copper and 556 ppm zinc with pH 1. 9 ; a 950-ml organic solution of 15 wt. % nonylsalicyl aldoxime and ketoxime extractant system (e. g., LIX 973N containing about 46% nonylsalicyl aldoxime, 18% ketoxime, 6% nonylphenol, and 30% diluent), 2 wt. % dodecanol, and 83 wt. % n-dodecane ; and a 50-ml strip solution of 3 M sulfuric acid were used.
The pH of the feed solution was maintained at 1. 9 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 12.
The copper concentration of the feed solution was changed from 151 ppm to 0. 07 ppm in just 90 minutes using the recycle mode of operation for both the feed solution and the strip dispersion. On the other hand, the copper was recovered and concentrated to more than 10, 000 ppm in the aqueous strip solution in 2 hours. The copper concentration in the strip solution was more than 70 times the original feed concentration.
Table 12
EXAMPLE 13 ZINC REMOVED TO LOW CONCENTRATION IN TREATED FEED AND CONCENTRATED TO HIGH CONCENTRATION IN STRIP The experimental procedure for this example was the same as that described in Examples 1 and 12, except that the 5-liter feed solution treated in Example 12 containing 556 ppm zinc with pH 1. 9 ; a 850-ml organic solution of 8 wt. % di (2, 4, 4- trimethyl-pentyl) dithiophosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol, and 90 wt. % n-dodecane ; and a 150-ml strip solution of 3 M sulfuric acid were used.
The pH of the feed solution was maintained at 1. 9 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 13.
The zinc concentration in the feed solution was changed from 556 ppm to 0. 275 ppm in just 2 hours using the recycle mode of operation for both the feed solution and the strip dispersion. On the other hand, the zinc was recovered and concentrated to more than 17, 000 ppm in the aqueous strip solution at the same time. The zinc concentration in the strip solution was more than 31 times the original feed concentration.
Table 13
EXAMPLE 14 NICKEL REMOVED FROM FEED AND CONCENTRATED TO HIGH CONCENTRATION IN STRIP The experimental procedure for this example was the same as that described in Example 1, except that a 2-liter feed solution containing 2, 216 ppm nickel with pH 3 ; a 750-ml organic solution of 24 wt. % of the new extractant, di (2-butyloctyl) monothiophosphoric acid (C12 MTPA), 4 wt. % dodecanol, and 72 wt. % n-
dodecane ; and a 250-ml strip solution of 2. 5 M sulfuric acid were used. The pH of the feed solution was maintained at 3 +/-0. 1 by adding 5 M NaOH as needed.
Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 14.
The nickel was removed from the feed solution, recovered, and concentrated to more than 10, 000 ppm in the aqueous strip solution in 30 minutes in the recycle mode of operation for both the feed solution and the strip dispersion. The nickel concentration in the strip solution was more than 4. 8 times the original feed concentration.
Table 14
EXAMPLE 15 COMPARATIVE EXAMPLE USING CONVENTIONAL D2EHPA FOR NICKEL The experimental procedure for this example was the similar to that described in example 14, except that a feed solution containing 2, 469 ppm nickel with pH 4. 5 and a organic solution containing 24 wt. % of the conventional extractant, di (2-ethylhexyl) phosphoric acid (D2EHPA), were used. The pH of the feed solution was maintained at 4. 5 +/-0. 1 by adding 5 M NaOH as needed.
Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 15.
As shown in this table, the nickel fluxes at the nickel concentrations of 2, 335 ppm and 1, 915 ppm in the feed solution at pH 4. 5 were 2. 30 and 1. 93 g/(m2*hr), respectively. These fluxes were significantly lower than those with the new extractant, C12 MTPA, described in Example 14, i. e., 3. 31 and 2. 79 g/(m2*hr) at even lower nickel concentrations of 2, 023 ppm and 1, 860 ppm in the feed solution at an even lower pH of 3, respectively. The flux of a metal increases as the concentration of the metal in the feed solution increases. In view of the feed pH reduction by proton transfer during extraction, an extractant operable at a lower pH can better utilize the length of the module than an extractant operable at a higher pH.
Thus, the new extractant, C12 MTPA, outperformed the conventional extractant, D2EHPA, significantly.
Table 15
EXAMPLE 16 MERCURY REMOVED TO VERY LOW CONCENTRATION IN TREATED FEED AND CONCENTRATED IN STRIP The experimental procedure for this example was the same as that described in Example 1, except that a 2-liter feed solution containing 0. 388 ppm mercury with pH 2. 5 ; a 525-ml organic solution of 10 wt. % oleic acid, 10 wt. % dodecanol, and 80 wt. % Isopar L ; and a 175-ml strip solution of 3 M nitric acid containing 3 wt. % sodium iodide were used. The pH of the feed solution was maintained at 2. 5 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 16.
The mercury concentration in the feed solution was changed from 0. 388 ppm to 0. 00084 ppm in just 15 minutes using the recycle mode of operation for both the
feed solution and the strip dispersion. The mercury was further reduced to less than 0. 00084 ppm in the feed solution, i. e., below the detection limit by ICP spectrometry, in the total run time of just 30 minutes, and it was recovered and concentrated to 21. 2 ppm in the aqueous strip solution at the same time. The mercury concentration in the strip solution was more than 54 times the original feed concentration.
Table 16
EXAMPLE 17 MERCURY REMOVED FROM 3 PPM FEED AND CONCENTRATED IN STRIP The experimental procedure for this example was the same as that described in examples 1 and 16, except that a 2-liter feed solution containing 3. 01 ppm mercury with pH 2. 5 ; a 525-ml organic solution of 10 wt. % oleic acid, 2. 5 wt. % dodecanol, and 87. 5 wt. % Isopar 1 ; and a 175-ml strip solution of 3 M nitric acid containing 3 wt. % sodium iodide were used. The pH of the feed solution was maintained at 2. 5 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by ICP as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 17.
As shown in this table, the mercury concentration in the feed solution was changed from 3. 01 ppm to 0. 0985 ppm in just 20 minutes using the recycle mode of operation for both the feed solution and the strip dispersion. On the other hand, the mercury was recovered and concentrated to 27. 4 ppm in the aqueous strip solution at the same time. The mercury concentration in the strip solution was more than 9 times the original feed concentration.
Table 17
EXAMPLE 18 THE SYNTHESIS OF DI (2-BUTYLOCTYL) MONOTHIOPHOSPHORIC ACID The alcohol 2-butyl-l-octanol 893 ml (4 moles) was mixed with 222g (1 mole) phosphorus pentasulfide (P2S5) and heated to about 90°C for a period of about at least 4 hours. Next, the intermediate reaction products were hydrolyzed with about 100 ml of 4N HCl at a temperature of about 100°C to about 120°C for a period of about 3 hours to about 4 hours. The hydolysis reaction was monitored by
FTIR to determine when the reaction was complete. The reaction mixture was then washed with water to remove any thiophosphoric acid (H3PSO4) formed. The reaction mixture was then distilled under vacuum to remove any unreacted 2-butyl- 1-octanol.
EXAMPLE 19 A fresh solution of 3 M H2SO4 was prepared for use as the strip solution. A strip dispersion was then prepared by mixing together 250 ml of the 3 M H2SO4 solution and 750 ml of n-dodecane containing 2% dodecanol and 8% 2-butyl-l-octyl phenylphosphonic acid (BOPPA) as described in the general procedure above. The strip dispersion was fed into the shell side of a polypropylene hollow fiber module.
A feed solution containing the following metals was passed into the tube side of the hollow fiber module : strontium (Sr ; 5 ppm), calcium (Ca ; 80 ppm), magnesium (Mg ; 20 ppm), or zinc (Zn ; 50 ppm). The pH of the feed solution was maintained at 3. 0 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals as described in the general procedure above and analyzed by ICP. Fluxes and k values were then calculated and are reported in Tables 18 to 21.
The organic phase extracted the Sr and other ions well at pH 3, but the stripping was poor (1-3 ppm). The Mg and Sr were extracted to a similar degree, while Ca was removed after a 15 minute run. Therefore, 1 M HCl was used as the strip solution for Example 20.
Table 18
EXAMPLE 20 A fresh solution of 1 M HCl was prepared for use as the strip solution. A strip dispersion was then prepared by mixing together 250 ml of the 1 M HCl solution and 750 ml of n-dodecane containing 2% dodecanol and 8% BOPPA as described in the general procedure above. The strip dispersion was fed into the shell side of a polypropylene hollow fiber module. A feed solution containing the following metals was passed into the tube side of the hollow fiber module : strontium (Sr ; 5 ppm), calcium (Ca ; 80 ppm), magnesium (Mg ; 20 ppm), or zinc (Zn ; 50 ppm). The pH of the feed solution was maintained at 3. 0 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals as described in the general procedure above and analyzed by ICP. Fluxes and k values were then calculated and are reported in Tables 22 to 25. The 1 M HC1 strip solution was found to be a better stripping agent than the than 3 M H2SO4.
Table 22
EXAMPLE 21 A fresh solution of 3 M HCl was prepared for use as the strip solution. A strip dispersion was then prepared by mixing together 250 ml of the 3 M HCl solution and 750 ml of n-dodecane containing 2% dodecanol and 8% BOPPA as described in the general procedure above. The strip dispersion was fed into the shell side of a polypropylene hollow fiber module. A feed solution containing the following metals was passed into the tube side of the hollow fiber module : strontium (Sr ; 5 ppm), calcium (Ca ; 80 ppm), magnesium (Mg ; 20 ppm), or zinc (Zn ; 50 ppm). The pH of the feed solution was maintained at 3. 0 +/-0. 1 by adding
5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals as described in the general procedure above and analyzed by ICP.
Fluxes and k values were then calculated and are reported in Tables 26. No obvious improvement was seen using the 3 M HCL strip solution over the 1 M HCl strip solution.
Table 26
EXAMPLE 22 A fresh solution of 1 M HCl was prepared for use as the strip solution. A strip dispersion was then prepared by mixing together 250 ml of the 1 M HC1 solution and 750 ml of n-dodecane containing 2% dodecanol and 8% BOPPA as described in the general procedure above. The strip dispersion was fed into the shell side of a polypropylene hollow fiber module. A feed solution containing the following metals was passed into the tube side of the hollow fiber module : strontium (Sr ; 5 ppm), calcium (Ca ; 80 ppm), magnesium (Mg ; 20 ppm), or zinc
(Zn ; 50 ppm). The pH of the feed solution was maintained at 2. 5 +/-1. 0 by adding 5 M NaOH as needed. Samples of the feed and strip solutions were collected at timed intervals as described in the general procedure above and analyzed by ICP. Fluxes and k values were then calculated and are reported in Tables 30 to 33. The results of the extraction at pH 2. 5 was slightly worse than those at pH 3, but most of the Sr was removed after 70 minutes.
Tables 30
EXAMPLE 23 COMPARISON BETWEEN BOPPA AND DEHPA The experimental procedure for this example using di (2-ethyl-l-hexyl) phosphoric acid (DEHPA) with feed pH 2. 5 was similar to that described in Example 22 except DEHPA was used instead of BOPPA. Fluxes and k values for strontium were calculated and are reported in Table 34. As shown in Table 34, and as compared with the results in Example 22, the strontium removal results with DEHPA at feed pH 2. 5 were poor and much worse than those with BOPPA. In
addition, an experiment using DEHPA at feed pH 4. 5 resulted in the formation of white solid precipitates in the feed solution, presumably from the formation of a solid complex between DEHPA and zinc in the feed solution. The precipitates blocked the flow of the feed through the module and stopped the experiment.
Therefore, the BOPPA extractant is much better than the DEHPA extractant for the removal of strontium.
Table 34
EXAMPLE 24 The experimental procedure for this example was the same as that described in Example 20, except that 2-hexyl-l-decyl phenylphosphonic acid (C16 HDPPA) was used instead of BOPPA. Fluxes and k values for strontium were calculated and are reported in Table 35. As shown in this table, the C16 HDPPA extractant removed strontium very well.
Table 35
Fluxes and k values for strontium were calculated and are reported in Table 36. As shown in this table and as compared with the results in Example 24, the strontium removal results with C16 DEHPA were poor and much worse than those with C16 HDPPA. In addition, the strip dispersion with C16 DEHPA turned into an emulsion, and it was difficult to separate into two phases, the organic liquid phase and the aqueous strip phase, upon standing. In other words, the C16 HDPPA extractant was much better than the C16 DEHPA extractant for the removal of strontium.
TABLE 36
EXAMPLE 26 The experimental procedure for this example was the same as that described in Example 20, except that a mixture of 2-hexyl-1-dodecyl/2-octyl-1-decyl phenylphosphonic acids (C18 HDPPA/ODPPA) was used instead of BOPPA.
Fluxes and k values for strontium were calculated and are reported in Table 37. As shown in this table, the C18 HDPPA/ODPPA extractant mixture removed strontium very well.
Table 37
EXAMPLE 27 The experimental procedure for this example was the same as that described in Example 20, except that 2-octyl-1-dodecyl phenylphosphonic acid (C20 ODPPA) was used instead of BOPPA. Fluxes and k values for strontium were calculated and are reported in Table 38. As shown in this table, the C20 ODPPA extractant removed strontium very well.
Table 38
EXAMPLE 28 RADIOACTIVE STRONTIUM-90 EXPERIMENTS A series of ten experiments using the combined supported liquid membrane (SLM)/strip dispersion process of the present invention were carried out by the use of radioactive strontium-90. For these experiments, the experimental procedure and conditions were similar to those described earlier in the general procedure except those noted below specifically. The following paragraphs describe the Experiments, Results, and Conclusions.
EXPERIMENTS Two separate organic solutions were used in the experiments. The first organic solution was freshly prepared with a composition of 8 wt % C20 ODPPA, 2
wt % dodecanol, and 90 wt % dodecane (42. 6 g of C20 ODPPA), which was used in Experiments #1, 2, 3, and 4 with a low feed concentration of 317 pico Curie per liter (pCi/L) strontium-90 and Experiment #9 with a low feed concentration of 1, 000 pCi/L. This solution was also used later in Experiment #10 with a high feed concentration of 487, 000 pCi/L Sr-90. The second organic solution used for Experiments #5 and 6 with a low feed concentration of 1, 000 pC/L Sr-90 and for Experiments #7 and 8 with a high feed concentration of 27, 941 pCi/L was made from two used solutions of the same composition employed in Experiments #1, 2, 3, 4, and 9 with the low feed concentrations.
The strip dispersions were made up of 1. 0 M HCl and the previously mentioned organic solutions. The total strip dispersion volume used was about 1 L (0. 25 L acid strip solution and 0. 75 L organic solution), except for Experiments #7, 8, and 10 where 0. 6 L was used (#7 and 8 with 0. 1 L acid strip solution and 0. 5 L organic solution, #10 with 0. 040 L acid solution and 0. 560 L organic solution). A fresh acid strip solution was used for each experiment.
All of the feed solutions were run at a pH of 3. 0. The pH was maintained between 2. 9 and 3. 0 by the addition of 5. 0 M NaOH. Four different feed solutions were used. As mentioned, Experiments #1-4 used a feed solution of 317 pCi/L.
Experiments #5, 6, and 9 used a feed solution of 1, 000 pCi/L. Experiments #7 and 8 used a feed solution of about 27, 941 pCi/L. Experiment #10 used a feed solution of about 487, 000 pCi/L. All of the runs except Experiment #10 used two liters of feed solution. Experiment #10 used one liter of feed. All of the runs used ground water.
The aqueous feed solutions for Experiments #4, 6, 8, and 9 had calcium, magnesium, and zinc added to them to make their concentrations of about 80 ppm, 20 ppm, and 50 ppm, respectively.
For these experiments, the feed outlet pressure was maintained between 4-4. 5 psi, and the strip dispersion inlet pressure was maintained between 1-2 psi.
The feed inlet pressure was maintained between 5-5. 5 psi.
Samples were taken during the experiments from the discharge of the module and not from the bulk solution. The sample volumes taken were at least 100 mL. Two strip samples were analyzed after diluting the sample 1 : 100. The strontium-90 concentrations were measured by filtering the sample through 3M's EMPORE (D filter paper, which selectively traps about 97% of Sr-90. The samples were prepared in the following manner per the manufacturer's directions.
Concentrated nitric acid was added to the sample to make a 2. 0 N nitric acid solution. The sample was then stirred and allowed to sit. One of the filter papers was placed in a filter support and conditioned with 10 mL of methanol for approximately 1 minute. After one minute, the methanol was pulled through the filter, followed immediately by 20 mL of 2. 0 M HNO3. Immediately following the nitric acid, the sample was added to the filter. The directions called for the sample to be passed through the filter at a rate of about 50 mL/min. Most of the samples were passed through the filter at no more than 25 mL/min ; this ensured the capture of Sr-90 by the filter. The sample was immediately followed by 20 mL of 2. 0 M HNO3. The filter was then dried under a heat lamp and was analyzed by a gas flow proportional counter, Tennelec 1000 series, Low Background Alpha/Beta Counting System. Due to a limited number of filters and the expense of each filter, only selected samples were analyzed.
RESULTS LOW FEED CONCENTRATION EXPERIMENTS : Experiments #1, 2, and 3 were all done using the same parameters and 317 pCi/L Sr-90 starting concentration. In all of these experiments, the target concentration of below 8 pCi/L in the treated ground water was achieved. In Experiment #4 with calcium, magnesium, and zinc added to the feed water, the Sr- 90 was reduced to below the target concentration within four hours. The data from these experiments along with all of the rest of the ten experiments are shown in Table 39 at the end of this example. Also included in this table are the mass transfer coefficient k values determined from all of the experiments.
Three experiments using the C20 ODPPA extractant were done using a starting Sr-90 concentration of 1, 000 pCi/L. One run was made with just Sr-90, and a second run was made using Sr-90 with calcium, magnesium, and zinc, Experiments #5 and 6, respectively. The third experiment, Experiment #9, was done with the feed containing Sr-90, calcium, magnesium, and zinc. In all three of these experiments, the treated feed concentration was expected to reach about 50 pCi/L Sr-90. All these experiments reached or exceeded that goal. Experiments #9 reduced the Sr-90 concentration in the feed to <8 pCi/L.
HIGH CONCENTRATION EXPERIMENTS : Two experiments, #7 and 8, were done using a starting feed concentration of about 27, 941 pCi/L Sr-90. Both experiments were done using a reduced strip and organic volumes of 0. 100 L and 0. 500 L, respectively. In Experiment #7, the final Sr-90 concentration in the feed after three hours was 222 pCi/L. The strip Sr-90 concentration was tested after three hours and was found to be about 60, 000 pCi/L.
The concentration was expected to be much higher, about 300, 000 pCi/L. The lack of concentration in the strip was probably due to a significant amount of the strip solution trapped in the module from the previous run. This effectively increased the volume of the strip solution, reducing the maximum concentration of Sr-90 achievable in the strip solution. This trapped liquid was not purged (which could be done with air purging, if available), and it was present in all of the experiments.
Experiment #8 added calcium, magnesium, and zinc to the feed in addition to 27, 941 pCi/L of Sr-90. At the end of five hours, the Sr-90 concentration in the feed was 84. 0 pCi/L, and the strip concentration was 263, 382 pCi/L. The feed result was better than expected, and the strip result was acceptable.
One other experiment was run, Experiment #10 using the used organic solution from Experiments #1, 2, 3, and 4. The strip solution volume was reduced to 0. 040 L, and 0. 560 L of the organic solution was used. The experiment was run for three hours, and it had a final feed Sr-90 concentration of 1, 562 pCi/L, reduced from about the initial concentration of 487, 000 pCi/L, and a final strip concentration of 1, 219, 577 pCi/L.
CONCLUSIONS It has been demonstrated that Sr-90 can be removed from ground water solutions effectively with the combined supported liquid membrane/strip dispersion process of the present invention. This process was very effective to remove Sr-90 from feed solutions containing about 300-1, 000 pCi/L Sr-90 to the target concentration of less than 8 pCi/L in the treated feed solutions. Especially, this target concentration was also achieved from a ground water solution containing about 1, 000 pCi/L Sr-90, 80 ppm calcium, 20 ppm magnesium, and 50 ppm zinc.
The feed solutions used containing these ions simulated the ground waters at Brookhaven National Laboratory and West Valley, NY.
Two strip solutions were generated with Sr-90 concentrations above 250, 000 pCi/L. The first was generated from a feed solution of 27, 941 pCi/L and resulted in a Sr-90 strip concentration of 263, 382 pCi/L. The second was generated from a feed solution of about 497, 000 pCi/L and resulted in a Sr-90 strip concentration of 1, 216, 577 pCi/L.
The new extractant, C20 ODPPA, was very effective for the removal of Sr- 90, and it gave consistent results below 8 pCi/L Sr-90 in the treated feed solutions.
The treated feed and used strip solution samples that were analyzed did not have any problems while filtering and did not have any cloudiness, indicating insignificant solubility of this extractant in the aqueous feed and strip solutions.
Table 39 : Strontium-90 Testing Results
* Strontium 90 concentration corrected for 97% removal efficiency of the filters and Y-90 in-growth as a function of time from the preparation of the filtered sample to the radioactivity counting analysis.
** Average of the shown analyses ++ Mass transfer coefficients were calculated using 317 pCi/L, 1, 000 pCi/L, 27, 941 pCi/L and 487, 000 pCi/L feed concentrations for the respective experiments.
EXAMPLE 29 2-Butyl-l-octyl (C12) phenylphosphonic acid (BOPPA) was synthesized by the following reaction. A solution of 45 g of 2-butyl-l-octanol in 100ml of pyridine
was prepared. A solution of 51 g of phenylphosphonyl dichloride in 100 ml of pyridine was also prepared. The 2-butyl-l-octanol solution was added dropwise to the phenyl phosphonyl dichloride solution at a temperature between 5 and 10°C over a period of 30 minutes. The reaction was then allowed to continue at the same temperature for an additional hour while the mixture was stirred. Then, 300 ml of concentrated HCl and about 200 g of ice were added to the reaction mixture, resulting in a solution having a pH of 1. The BOPPA was then extracted from the reaction mixture with 200 ml of toluene. The BOPPA/toluene solution was washed with 200 ml of 1 M HCl solution and dried with MgSO4 to produce a clear solution.
BOPPA (60 g) was obtained by evaporating the toluene at 60°C for 30 minutes.
EXAMPLE 30 BOPPA was also synthesized by the following reaction (with different reactant amounts from those used in Example 29). A solution of 31. 5 g of 2-butyl- 1-octanol in 70ml of pyridine was prepared. A solution of 44 g of phenylphosphonyl dichloride in 70 ml of pyridine was also prepared. The 2-butyl-1- octanol solution was added dropwise to the phenyl phosphonyl dichloride solution at a temperature between 5 and 10°C over a period of 30 minutes. The reaction was then allowed to continue at the same temperature for an additional 4-8 hours while the mixture was stirred. Then, 200 ml of concentrated HCl and about 200 g of ice were added to the reaction mixture, resulting in a solution having a pH of approximately 1. The mixture was allowed to stir for 24 hours. The BOPPA was then extracted from the reaction mixture with 200 ml of toluene. The BOPPA/toluene solution was washed with 200 ml of 1 M HCl solution and dried with MgSO4 to produce a clear solution. BOPPA at a yield of about 90% based on
the alcohol reactant was obtained by evaporating the toluene at 80°C for approximately 30 minutes.
EXAMPLE 31 2-Hexyl-l-decyl phenylphosphonic acid (C16 HDPPA) was synthesized by the use of the same procedure described in Example 30 except 41 g of 2-hexyl-1- decanol was used instead of 31. 5 g of 2-butyl-l-octanol.
EXAMPLE 32 2-Octyl-1-decyl/2-hexyl-1-dodecyl phenylphosphonic acid (C18 ODPPA/HDPPA) was synthesized by the use of the same procedure described in Example 30 except 45. 7 g of a mixture of 2-octyl-l-decanol and 2-hexyl-1- dodecanol was used instead of 31. 5 g of 2-butyl-l-octanol.
EXAMPLE 33 2-Octyl-l-dodecyl phenylphosphonic acid (C20 ODPPA) was synthesized by the use of the same procedure described in Example 30 except 50. 5 g of 2-octyl-1- dodecanol was used instead of 31. 5 g of 2-butyl-l-octanol.
GENERAL PROCEDURES FOR EXAMPLES 34 T036 The strip dispersion for each of the following examples was prepared by mixing an aqueous strip solution in a quantity, for example, 200 ml, of an organic extractant solution. The organic extractant solution can be, for example, Isopar L, an isoparaffinic hydrocarbon solvent with a flash point of 62°C, a boiling point of 207°C, a viscosity of 1. 5 cp (at 25°C), and a density of 0. 767 g/ml (at 15. 6°C), containing 1 wt. % o-nitrophenyl octyl ether (o-NPOE) and 10 wt. % N-lauryl-N-
trialkylmethylamine with a molecular weight of 372 (or a total number of 25. 3 carbon atoms per amine molecule, e. g., Amberlite LA-2). A quantity of combined aqueous strip solution/organic extractant solution, for example, 800 ml, was introduced into a Fisher brand mixer with a 2-inch diameter, 6-bladed, high-shear impeller at 500 rpm as measured by Ono Sokki HT-4100 tachometer. The mixer was plugged into a varistat to allow for adjustable speed control. The impeller was initially started at 50% of the full power and varistat at 80%.
All of the following examples were run in countercurrent fashion with the feed solution passed through the tube side of the microporous polypropylene hollow-fiber module. The microporous polypropylene hollow-fiber module of 2. 5 inches in diameter and 8 inches in length, providing a surface area of 1. 4 square meters. The process was first started by passing water through the hollow fiber module. Once pressures were adjusted and stable, the water was then replaced with the feed solution. A positive pressure was maintained on the feed side to prevent the organic phase in the shell side from passing through the pores of the hollow fibers.
The pressure of the inlet on the shell side was maintained at 1. 5 psi and the outlet pressure of the feed side was set at 11. 5 psi, thus maintaining a 10 psi differential between the two sides. In each of the runs, the feed flow was adjusted to give a flow rate of approximately 0. 84 liter/min at these pressures. The typical feed solution volume for these experiments was 1 liter.
Samples from the feed solution and the strip dispersion were taken at timed intervals. The strip dispersion samples were allowed to stand until a phase separation occurred. The aqueous phase from the strip dispersion sample was then collected and centrifuged to facilitate complete separation. The aqueous phase
samples from the strip dispersion samples and the feed solution samples were then analyzed by an ultraviolet (UV) spectrophotometer.
The flux of a species removed from the feed solution can be defined by the following formula : V AC flux =---- t A where V is the volume of the feed solution treated ; AC is the concentration change in the feed solution ; t is the time at which the sample is taken ; and A is the membrane surface area. The flux of the species was calculated from the above equation.
The mass transfer coefficient k of the species removed from the feed solution can be defined by the following formula : V C. k=-----m(--) t =-----------In (----) where C 0 is the initial concentration of the species in the feed solution ; C, is the concentration of the species in the feed solution at time t ; t is the time ; and the rest of the symbols are as defined above. The mass transfer coefficient k of the species was calculated from the above equation.
EXAMPLE 34 A strip dispersion was prepared by mixing together 200 ml of the 1. 2 M sodium carbonate (Na2CO3) solution and 800 ml of an organic solution containing 10 wt. % N-lauryl-N-trialkylmethylamine with a molecular weight of 372 (a total number of 25. 3 carbon atoms per amine molecule, e. g., Amberlite LA-2), 1 wt. : % o- nitrophenyl octyl ether (o-NPOE), and 89 wt. % Isopar L as described in the general procedure above. The strip dispersion was fed into the shell side of a 2. 5-inch polypropylene hollow fiber module. One liter of feed solution containing penicillin G at a concentration of 8, 840 parts per million (ppm) was passed into the tube side of the hollow fiber module. The pH of the feed solution was maintained at 3 +/-0. 1 by adding 3 M sulfuric acid as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by UV as described in the general procedure above. Fluxes and k values were then calculated and are presented in the Table 40.
Penicillin G was removed from a high concentration of 8, 840 ppm to a relatively low concentration of 1, 161 ppm in the feed solution in 2. 5 hours in the recycle mode of operation for both the feed solution and the strip dispersion. The penicillin G was recovered and concentrated to a high concentration of 40, 802 ppm in the aqueous strip solution at the same time. This represented a recovery efficiency of 92. 3%. After 4 hours of processing, the penicillin G was removed to a low concentration of less than 600 ppm in the feed solution, and it was recovered and concentrated to about 40, 000 ppm in the aqueous strip solution. The results of the experiment are listed in Table 40 below. The penicillin G flux of 9. 42 g/(m2*hr) at the penicillin G concentration of 2, 246 ppm in the feed solution was very high.
Table 40
EXAMPLE 35 A strip dispersion was prepared by mixing together 200 ml of the 1. 2 M sodium carbonate (Na2CO3) solution and 800 ml of an organic solution containing 10 wt. % N-lauryl-N-trialkylmethylamine with a molecular weight of 372 (a total number of 25. 3 carbon atoms per amine molecule, e. g., Amberlite LA-2), 1 wt. % o- nitrophenyl octyl ether (o-NPOE), and 89 wt. % Isopar L as described in the general procedure above. The strip dispersion was fed into the shell side of a 2. 5-inch polypropylene hollow fiber module. One liter of feed solution containing penicillin G at a concentration of 9, 609 ppm was used. The pH of the feed solution was maintained at 4 +/-0. 1 by adding 3 M sulfuric acid as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by UV as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 41.
Penicillin G was removed from a high concentration of 9, 609 ppm to a concentration of 2, 837 ppm in the feed solution in 2. 5 hours in the recycle mode of
operation for both the feed solution and the strip dispersion. Penicillin G was recovered and concentrated to a high concentration of 44, 739 ppm in the aqueous strip solution at the same time. This represented a recovery efficiency of 83. 6%. At the 5 hours in the recycle operation, the penicillin G was removed to a concentration of 1, 540 ppm in the feed solution, and it was recovered and concentrated to a very high concentration of 55, 064 ppm in the aqueous strip solution. This represented a recovery efficiency of 90. 5%. The penicillin G flux at the penicillin G concentration of 6, 499 ppm in the feed solution at pH 4 was 4. 44 g/(m2*hr), which was lower than the flux at pH 3 described in Example 34.
Table 41
EXAMPLE 36 A strip dispersion was prepared by mixing together 200 ml of the 1. 2 M sodium carbonate (Na2CO3) solution and 800 ml of an organic solution containing 10 wt. % N-lauryl-N-trialkylmethylamine with a molecular weight of 372 (a total number of 25. 3 carbon atoms per amine molecule, e. g., Amberlite LA-2), 1 wt. % o-
nitrophenyl octyl ether (o-NPOE), and 89 wt. % Isopar L as described in the general procedure above. The strip dispersion was fed into the shell side of a 2. 5-inch polypropylene hollow fiber module. One liter of feed solution containing penicillin G at a concentration of 9, 125 ppm was used. The pH of the feed solution was maintained at 5 +/-0. 1 by adding 3 M sulfuric acid as needed. Samples of the feed and strip solutions were collected at timed intervals and analyzed by UV as described in the general procedure above. Fluxes and k values were then calculated and are reported in Table 42 below.
As reported in Table 42, the penicillin G was removed from a high concentration of 9, 125 ppm to a concentration of 6, 547 ppm in the feed solution in 2. 5 hours in the recycle mode of operation for both the feed solution and the strip dispersion. Penicillin G was recovered and concentrated to a concentration of 7, 434 ppm in the aqueous strip solution at the same time. This represented a recovery efficiency of 16. 3%. At the 5 hours in the recycle operation, the penicillin G was removed to a concentration of 4, 544 ppm in the feed solution, and it was recovered and concentrated to a concentration of 24, 579 ppm in the aqueous strip solution.
This represented a recovery efficiency of 53. 9%. The penicillin G flux at the penicillin G concentration of 8, 511 ppm in the feed solution at pH 5 was 0. 88 g/(m2*hr), which was lower than the flux values at pH 3 described in Example 34 and at pH 4 described in Example 35. Thus, the flux increased as the feed pH reduced.
Table 42
EXAMPLE 37 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH LYSINE A microporous polypropylene hollow-fiber module of 2. 5 inches in diameter by 8 inches in length (with a surface area of 1. 4 m2) was used in the in-situ interfacial polymerization for the preparation of the microporous support with an interfacial polymerized layer for use with the supported liquid membrane (SLM) with a strip dispersion. In the in-situ interfacial polymerization, the module was mounted vertically.
A 1-liter aqueous solution of 2. 54 wt. % L-lysine monohydrate in distilled water was recycled upwards vertically through the tube side of the module at a flow rate of 1 liter/min. The pressure at the outlet of this aqueous stream from the module was adjusted to 10 psig. Isopar G, which was an isoparaffinic hydrocarbon solvent (with a flash point of 41°C, a boiling point of 176°C, a viscosity of 1 cp (at
25°C), and a density of 0. 747 g/ml (at 15. 6°C)), was recycled through the shell of the module for 10 minutes, and it was then drained. The interfacial polymerization was carried out by recycling a 1-liter organic solution of 0. 12% (w/v) trimesoyl chloride (TMC) in Isopar G (0. 12 g TMC per 100 ml Isopar G) upwards vertically through the shell side of the module for 1. 5 minutes. The counting of the interfacial polymerization time was started when the organic solution was observed at its outlet from the top of the module.
The interfacial polymerization reaction was terminated by washing the tube side (the aqueous amine solution side) with water by recycling 2-liter water upwards vertically through the tube side at a flow rate of 1 liter/min and an outlet pressure of 10 psig. With the water recycling in the tube side, the organic solution in the shell side was drained, followed by recycling 2-liter water for one hour. The water from the shell side was then removed, and the shell side was dried with compressed air (at an inlet pressure of 1 psig) for one hour. Finally, the water from the tube side was drained before the use of the module for the SLM with a strip dispersion.
EXAMPLE 38 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH AMINOETHYLPIPERAZINE (1. 5 MIN) The experimental procedure for this example was the same as that described in Example 37 except a 1-liter aqueous solution of 2 wt. % 1- (2- aminoethyl) piperazine in distilled water was used.
EXAMPLE 39 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH AMINOETHYLPIPERAZINE (2 MIN) The experimental procedure for this example was the same as that described in Examples 37 and 38 except a 1-liter aqueous solution of 2 wt. % 1- (2- aminoethyl) piperazine in distilled water and an interfacial polymerization time of 2 minutes were used.
EXAMPLE 40 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH TRIETHYLENETETRAAMINE The experimental procedure for this example was the same as that described in Example 37 except a 0. 75-liter aqueous solution of 2. 27 wt. % triethylenetetraamine in distilled water was used.
EXAMPLE 41 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH PIPERAZINE The experimental procedure for this example was the same as that described in Example 37 except a 1-liter aqueous solution of 2. 33 wt. % piperazine in distilled water and an outlet pressure of 3 psig for the aqueous solution were used.
EXAMPLE 42 HOLLOW FIBER MODULE OF MICROPOROUS SUPPORT WITH AN INTERFACIAL POLYMERIZED LAYER FROM IN-SITU INTERFACIAL POLYMERIZATION WITH HEXAMETHYLENEDIAMINE The experimental procedure for this example was the same as that described in Example 37 except a 0. 75-liter aqueous solution of 1. 80 wt. % hexamethylenediamine in distilled water and an outlet pressure of 5 psig for the aqueous solution were used.
EXAMPLE 43 SLM WITH A STRIP DISPERSION FOR STRONTIUM A strip dispersion is then prepared by mixing together 250 ml of the 1 M HC1 solution and 750 ml of n-dodecane containing 2% dodecanol and 8% 2-butyl-1- octyl phenylphosphonic acid (BOPPA) in a Fisher brand mixer with a 2-inch diameter, 6-bladed, high-shear impeller at 500 rpm as measured by Ono Sokki HT- 4100 tachometer. The mixer is plugged into a varistat to allow for adjustable speed control. The impeller is initially started at 50% of the full power and varistat at 80%. The strip dispersion is fed into the shell side of a hollow fiber module of microporous polypropylene support with an interfacial polymerized layer prepared from the in-situ interfacial polymerization technique described in Example 37.
The run using the SLM with the strip dispersion is conducted in countercurrent fashion with the feed (or tube) side of the module started first using water. The water is then replaced with the feed solution once the pressures are adjusted and stable. A positive pressure is maintained on the feed side to prevent
the organic phase in the shell side from passing through the pores of the hollow fibers.
The pressure of the inlet on the shell side is maintained at 1. 25 psi and the outlet pressure of the feed side is set at 3. 25 psi, thus maintaining a 2 psi differential between the sides. The feed flow is adjusted to give a flow rate of approximately 0. 84 liter/min at these pressures.
A 2-liter feed solution containing the following metals is passed into the tube side of the hollow fiber module : strontium (Sr ; 5 ppm), calcium (Ca ; 80 ppm), magnesium (Mg ; 20 ppm), or zinc (Zn ; 50 ppm). The pH of the feed solution is maintained at 3. 0 +/-0. 1 by adding 5 M NaOH as needed. Samples of the feed and strip solutions are taken at timed intervals. The strip dispersion samples are allowed to stand until a decent phase separation is seen. The aqueous phase from the strip dispersion sample is then collected and centrifuged to facilitate complete separation.
The aqueous phase samples from the strip dispersion samples and the feed solution samples are analyzed by inductively coupled plasma (ICP) spectrometry.
EXAMPLE 44 SLM WITH A STRIP DISPERSION FOR COBALT The experimental procedure for this example is the same as that described in Example 43 except a 4-liter feed solution containing 562 ppm cobalt at pH 2. 3, a 600-ml organic solution containing 8 wt. % di (2, 4, 4-trimethylpentyl) dithiophosphinic acid (e. g., Cyanex 301), 2 wt. % dodecanol, and 90 wt. % Isopar L (isoparaffinic hydrocarbon solvent with a flash point of 62°C, a boiling point of 207°C, a viscosity of 1. 5 cp (at 25°C), and a density of 0. 767 g/ml (at 15. 6°C)), and
a 200-ml aqueous strip solution of 2. 5 M H2SO4 are used. The pH of the feed solution is maintained at 2. 3 +/-0. 1 by adding 5 M NaOH as needed.
EXAMPLE 45 SLM WITH A STRIP DISPERSION FOR PENICILLIN G The experimental procedure for this example is the same as that described in Example 43 except a 1-liter feed solution containing a penicillin G concentration of 8, 840 ppm at pH 3, a 800-ml organic solution containing 10 wt. % N-lauryl-N- trialkylmethylamine with a molecular weight of 372 (a total number of 25. 3 carbon atoms per amine molecule, e. g., Amberlite LA-2)), 1 wt. % o-nitrophenyl octyl ether (o-NPOE), and 89 wt. % Isopar, an aqueous strip solution of 200 ml of 1. 2 M sodium carbonate (Na2CO3), a differential pressure of 10 psi between the feed and strip dispersion sides are used. The pH of the feed solution is maintained at 3 +/-0. 1 by adding 3 M sulfuric acid as needed.