CHOROVER JONATHAN D (US)
SIERRA-ALVAREZ MARIA REYES (US)
| US20130006018A1 | 2013-01-03 | |||
| US20090000194A1 | 2009-01-01 |
| CLAIMS 1. A method to convert an insensitive munitions compound (IMC) to gaseous products comprising the steps of: subjecting the IMC to a first stage reduction step followed by a second stage oxidation step. 2. The method of claim 1 wherein the IMC is NTO or DNAN. 3. The method of claim 2 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO). 4. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with one or more Fen/Fein containing minerals. 5. The method of claim 3 wherein said one or more Fen/Feni containing minerals is green rust. 6. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR. 7. The method of claim 6 wherein said precursor of GR is a zero valent iron (ZVI). 8. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2+, a precursor of GR, GR, or Fen/Fein containing minerals. 9. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with an MnIvcontaining mineral. 10. The method of claim 9 wherein said MnIV containing mineral is birnessite (Mn02). 11. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with permanganate (MnO¾). 12. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with a combination of MnO¾ and Mn02. 13. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with one or more Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 14. The method of claim 13 wherein said one or more Fe /Fe containing minerals is green rust. 15. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR at 10 g kg-1 solid to solution ratio at pH 8.4. 16. The method of claim 15 wherein said precursor of GR is a zero valent iron (ZVI). 17. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2+, a precursor of GR, GR, or Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 18. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with an MnIvcontaining mineral at 15 g kg-1 solid to solution ratio at pH 7. 19. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with permanganate (MnO¾) at 15 g kg-1 solid to solution ratio at pH 7. 20. The method of claim 3 wherein said second stage converts ATO to CO2 and N2 with a combination of MnO¾ and Mn02 at 15 g kg-1 solid to solution ratio at pH 7. 21. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3- amino-l,2,4-triazol-5-one (ATO) by GR at 10 g kg-1 solid to solution ratio at pH 8.4 and wherein said second stage converts ATO into CO2 and N2 with birnessite (Mn02) at a SSR of 15 g kg"1, pH 7. 22. The method of claim 21 wherein said NTO is transformed into CO2 and N2 with cumulative hydraulic retention times of less than 10 minutes. 23. The method of claim 2 wherein DNAN is reductively transformed to 2-methoxy-5- nitroaniline (MENA). 24. The method of claim 23 wherein MENA is reductively transformed to 2,4- diaminoanisole (DAAN). 25. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5- nitroaniline (MENA) with one or more Fen/Fein containing minerals. 26. The method of claim 25 wherein said one or more Fe /Fe containing minerals is green rust. 27. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5- nitroaniline (MENA) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR. 28. The method of claim 27 wherein said precursor of GR is a zero valent iron (ZVI). 29. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5- nitroaniline (MENA) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2+, a precursor of GR, GR or Fen/Fein containing minerals. 30. The method of claim 23 wherein said second stage converts MENA to CO2 and N2 with an MnIvcontaining mineral. 31. The method of claim 30 wherein said MnIV containing mineral is birnessite (Mn02). 32. The method of claim 23 wherein said second stage converts MENA to CO2 and N2 with permanganate (MnO¾). 33. The method of claim 23 wherein said second stage converts MEAN to CO2 and N2 with a combination of MnO¾ and MnC>2. 34. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5- nitroaniline (MENA) with one or more Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 35. The method of claim 34 wherein said one or more Fen/Fein containing minerals is green rust. 36. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5- nitroaniline (MENA) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR at 10 g kg-1 solid to solution ratio at pH 8.4. 37. The method of claim 36 wherein said precursor of GR is a zero valent iron (ZVI). 38. The method of claim 23 wherein said first stage DNAN to 2-methoxy-5-nitroaniline (MENA) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2 +, a precursor of GR, GR or Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 39. The method of claim 23 wherein said second stage converts MENA to CO2 and N2 with an MnIvcontaining mineral at 15 g kg-1 solid to solution ratio at pH 7. 40. The method of claim 23 wherein said second stage converts MEAN to CO2 and N2 with permanganate (MnO¾) at 15 g kg-1 solid to solution ratio at pH 7. 41. The method of claim 23 wherein said second stage converts MENA to CO2 and N2 with a combination of MnO¾ and MnC>2 at 15 g kg-1 solid to solution ratio at pH 7. 42. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5 - nitroaniline (MENA) by GR at 10 g kg-1 solid to solution ratio at pH 8.4 and wherein said second stage converts MEAN into CO2 and N2 with birnessite (MnC>2) at a SSR of 15 g kg_1, pH 7. 43. The method of claim 42 wherein said DNAN is transformed into CO2 and N2 with cumulative hydraulic retention times of less than 10 minutes. 44. A method to transform NTO into CO2 and N2 comprising the steps of: providing a first stage of one or more packed bed reactors, said first stage reactors contain one or more materials that reduce the NTO; passing said NTO through said first stage of one or more packed bed reactors to create an effluent of ATO; and providing a second stage of one or more reactors that receive said ATO effluent, said one or more second stage reactors contain one or more materials that oxidize the ATO into C02 and N2 - 45. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with one or more Fen/Fein containing minerals. 46. The method of claim 45 wherein said one or more Fen/Fein containing minerals is green rust. 47. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR. 48. The method of claim 47 wherein said precursor of GR is a zero valent iron (ZVI). 49. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2 +, a precursor of GR, GR, or Fen/Fein containing minerals. 50. The method of claim 44 wherein said second stage converts ATO into CO2 and N2 with an MnIvcontaining mineral. 51. The method of claim 50 wherein said MnIV containing mineral is birnessite (Mn02). 52. The method of claim 44 wherein said second stage converts ATO into CO2 and N2 with permanganate (MnO^). 53. The method of claim 44 wherein said second stage converts ATO into CO2 and N2 with a combination of MnO¾ and Mn02. 54. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with one or more Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 55. The method of claim 54 wherein said one or more Fen/Fein containing minerals is green rust. 56. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR at 10 g kg-1 solid to solution ratio at pH 8.4. 57. The method of claim 56 wherein said precursor of GR is a zero valent iron (ZVI). 58. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2 +, a precursor of GR, GR or Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 59. The method of claim 44 wherein said second stage converts ATO to CO2 and N2 with an MnIvcontaining mineral at 15 g kg-1 solid to solution ratio at pH 7. 60. The method of claim 44 wherein said second stage converts ATO to CO2 and N2 with permanganate (MnO¾) at 15 g kg-1 solid to solution ratio at pH 7. 61. The method of claim 44 wherein said second stage converts ATO to CO2 and N2 with a combination of MnO¾ and MnC>2 at 15 g kg-1 solid to solution ratio at pH 7. 62. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) by GR at 10 g kg-1 solid to solution ratio at pH 8.4 and wherein said second stage converts ATO into CO2 and N2 with birnessite (Mn02) at a SSR of 15 g kg-1 at pH 7. 63. The method of claim 62 wherein said NTO is transformed into CO2 and N2 with cumulative hydraulic retention times of less than 10 minutes. 64. The method of claim 44 wherein said one or more second stage reactors are continuously receive permanganate (MnO^) that oxidize ATO and at the end of the reaction, MnO¾ forms Mn02. 65. The method of claim 44 wherein said first reactors contain sand mixed with GR, ZVI or iron minerals with adsorbed Fe2 + or combinations thereof and said second stage reactors contain sand mixed with MnO¾ or Mn02. 66. The method of claim 66 wherein said Mn02 coats the sand particles and provide a reservoir of the Mn02 oxidant in a packed bed reactor. 67. The method of claim 44 wherein said second stage reactors contain a solid phase mineral oxidant. 68. The method of claim 44 wherein said first stage materials are phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2+, or combinations thereof. 69. The method of claim 68 wherein said one or more mineral-based electron donating materials is GR or ZVI or combinations thereof. 70. A method to transform DNAN into CO2 and N2 comprising the steps of: providing a first stage of one or more packed bed reactors, said first stage reactors contain one or more materials that reduce the DNAN; passing said NTO through said first stage of one or more packed bed reactors to create an effluent of MENA; and providing a second stage of one or more reactors that receive said MENA effluent, said one or more second stage reactors contain one or more materials that oxidize the MENA into C02 and N2. 71. The method of claim 70 wherein said first stage reduces DNAN to 2 -methoxy-5 - nitroaniline (MENA) with one or more Fen/Fein containing minerals. 72. The method of claim 71 wherein said one or more Fen/Fein containing minerals is green rust. 73. The method of claim 70 wherein said first stage reduces DNAN to 2 -methoxy-5 - nitroaniline (MENA) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR. 74. The method of claim 73 wherein said precursor of GR is a zero valent iron (ZVI). 75. The method of claim 23 wherein said first stage reduces DNAN to 2-methoxy-5 - nitroaniline (MENA) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2+, a precursor of GR, GR or Fen/Fein containing minerals. 76. The method of claim 70 wherein said second stage converts MENA to CO2 and N2 with an MnIvcontaining mineral. 77. The method of claim 76 wherein said MnIV containing mineral is birnessite (MnC>2). 78. The method of claim 70 wherein said second stage converts MENA to CO2 and N2 with permanganate (MnO¾). 79. The method of claim 70 wherein said second stage converts MEAN to CO2 and N2 with a combination of MnO¾ and MnC^ . 80. The method of claim 70 wherein said first stage reduces DNAN to 2-methoxy-5 - nitroaniline (MENA) with one or more Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 81. The method of claim 80 wherein said one or more Fen/Fein containing minerals is green rust. 82. The method of claim 70 wherein said first stage reduces DNAN to 2 -methoxy-5 - nitroaniline (MENA) with one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2 +, or a precursor of GR at 10 g kg-1 solid to solution ratio at pH 8.4. 83. The method of claim 82 wherein said precursor of GR is a zero valent iron (ZVI). 84. The method of claim 70 wherein said first stage DNAN to 2-methoxy-5-nitroaniline (MENA) with a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2 +, a precursor of GR, GR or Fen/Fein containing minerals at 10 g kg-1 solid to solution ratio at pH 8.4. 85. The method of claim 70 wherein said second stage converts MENA to CO2 and N2 with an MnIvcontaining mineral at 15 g kg-1 solid to solution ratio at pH 7. 86. The method of claim 70 wherein said second stage converts MEAN to CO2 and N2 with permanganate (MnO^) at 15 g kg-1 solid to solution ratio at pH 7. 87. The method of claim 70 wherein said second stage converts MENA to CO2 and N2 with a combination of MnO¾ and MnC>2 at 15 g kg-1 solid to solution ratio at pH 7. 88. The method of claim 70 wherein said first stage reduces DNAN to 2-methoxy-5 - nitroaniline (MENA) by GR at 10 g kg-1 solid to solution ratio at pH 8.4 and wherein said second stage converts MEAN into CO2 and N2 with birnessite (MnC>2) at a SSR of 15 g kg_1, pH 7. 89. The method of claim 88 wherein said DNAN is transformed into CO2 and N2 with cumulative hydraulic retention times of less than 10 minutes. 90. The method of claim 70 wherein said one or more second stage reactors are continuously receive permanganate (MnO^) that oxidize ATO and at the end of the reaction, MnO¾ forms MnC^ . 91. The method of claim 70 wherein said first reactors contain sand mixed with GR, ZVI or iron minerals with adsorbed Fe2 + or combinations thereof and said second stage reactors contain sand mixed with MnO¾ or MnC^ . 92. The method of claim 91 wherein said MnC>2 coats the sand particles and provide a reservoir of the MnC>2 oxidant in a packed bed reactor. 93. The method of claim 70 wherein said second stage reactors contain a solid phase mineral oxidant. 94. The method of claim 70 wherein said first stage materials are phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2+, or combinations thereof. 95. The method of claim 94 wherein said one or more mineral-based electron donating materials is GR or ZVI or combinations thereof. 96. A system to convert an insensitive munitions compound (IMC) to gaseous products comprising: one or more first stage reactors containing one or more materials that reduce the IMC; one or more second stage reactors configured to receive an effluent from said one or more first stage reactors; and said one or more second stage reactors contain a material that oxidizes the received effluent. 97. The system of claim 96 wherein said first stage material is one or more Fen/Fein containing minerals. 98. The system of claim 97 wherein said one or more Fen/Fein containing minerals is green rust. 99. The system of claim 96 wherein said first stage material are one or more phase mineral materials, one or more mineral-based electron donating materials, one or more iron minerals with adsorbed Fe2+, or a precursor of GR. 100. The system of claim 99 wherein said precursor of GR is a zero valent iron (ZVI). 101. The system of claim 96 wherein said first stage material are a combination of one or more from the group comprising phase mineral materials, mineral-based electron donating materials, iron minerals with adsorbed Fe2+, a precursor of GR, GR or Fen/Feni containing minerals. 102. The systems of claims 97-101 wherein said first stage materials are at 10 g kg-1 solid to solution ratio at pH 8.4. 103. The system of claim 96 wherein said second stage material are an MnIvcontaining mineral. 104. The system of claim 102 wherein said MnIV containing mineral is birnessite (Mn02). 105. The system of claim 96 wherein said second stage material are permanganate (MnO¾). 106. The system of claim 96 wherein said second stage material are a combination of MnO¾ and Mn02. 107. The system of claims 103-106 wherein said second stage materials are at 15 g kg-1 solid to solution ratio at pH 7. 108. The method of claim 3 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with a zero valent iron (ZVI). 109. The method of claim 23 wherein said first stage reduces DNAN to 2- methoxy-5-nitroaniline (MENA) with a zero valent iron (ZVI). 110. The method of claim 44 wherein said first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with a zero valent iron (ZVI). 111. The method of claim 70 wherein said first stage reduces DNAN to 2- methoxy-5-nitroaniline (MENA) with a zero valent iron (ZVI). 112. The system of claim 96 wherein said first stage material is a zero valent iron (ZVI). |
HIGH-RATE TREATMENT OF 3-NITRO-l,2,4-TRIAZOL-5-ONE (NTO) AND OTHER
MUNITIONS COMPOUNDS
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No. 62482987 filed April 7, 2017, and herein incorporated by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT
[0002] This invention was made with government support under Grant No. W912HQ-12- C-0021, awarded by ARMY. The government has certain rights in the invention.
BACKGROUND OF THE INVENTION
[0003] The insensitive munitions compound (IMC), 3-nitro-l,2,4-triazol-5-one (NTO), poses an important environmental concern due to its high aqueous solubility. The high degree of solubility enables NTO to be very mobile in the environment where it could readily cause contamination of groundwater and other water bodies.
[0004] The occurrence of a nitro-group in NTO's structure renders the molecule susceptible to reductive reactions. Reduced iron-containing minerals are well known for their ability to catalyze the reduction of environmental contaminants. Among many Fe(II)- containing minerals, green rusts (GR) are often viewed as the most powerful iron reductants capable of reducing a wide variety of environmental contaminants. GRs are mixed valent iron (Fe n /Fe in ) layered hydroxides and substituted with anions (e.g. sulfate or bicarbonate). They are commonly formed during the biocorrosion of zero valent ion or steel.
[0005] Organohalogens such as perchloroethylene, trichloroethylene, cis- dichloroethylene and vinyl chloride have also been shown to be reductively dehalogenated by GR to ethylene, and ethane. Trichloronitromethane has also been observed to be rapidly degraded to methylamine, and several other disinfection byproducts were also
transformed by hydrolysis and hydrogenolysis. Pentachlorophenol has also been shown to be reductively dechlorinated by GR. GR are responsible for reducing the radionuclide Np(V) to Np(IV), the metal Cr(VI) to Cr(III) and selenate to elemental selenium. Nitrate is reduced to ammonium.
[0006] It has also been demonstrated that conventional explosive compounds were transformed by GR. RDX and HMX were transformed to nitroso-products; whereas TNT was reduced to aromatic amines. If a similar reaction were to occur with NTO, the organic amine, 3-amino-l,2,4-triazol-5-one (ATO) (Figure 1), would be expected from the reaction.
[0007] Organic amines such as aromatic amines are very susceptible to oxidation by manganese oxide minerals such as birnessite (Mn02). Birnessite can also oxidize aliphatic amines. The original parent compounds of the explosives have standard reduction potentials that are too high to be oxidized; however, as the explosive parent compounds are progressively reduced their reduction potential decrease which increases the oxidation of the molecules.
BRIEF SUMMARY OF THE INVENTION
[0008] In one embodiment, the present invention provides a system and method for the pretreatment for 3-Nitro-l,2,4-triazol-5-one (NTO), which is an insensitive munitions compound (IMC), that poses an important environmental concern due to its high aqueous solubility enabling to it to be very mobile in the environment.
[0009] In other embodiments, the present invention provides a system and method that convert NTO to mostly benign gaseous products (CO2 and N2) with a hydraulic retention time in the time scale of minutes. A first stage reduces NTO stoichiometrically to 3-amino- l,2,4-triazol-5-one (ATO) with the Fe n /Fe in containing mineral, green rust. A second stage converts ATO to CO2 and N2 with birnessite.
[00010] In still further embodiments, the present invention provides a system or method that is ideal for treating NTO in munitions wastewater or groundwater and works for other IMCs such as 2,4-dintroanisole (DNAN).
[00011] In other embodiments, the present invention provides a pretreatment step that assists in the degradation of aromatic compounds with nitro substituents (explosives, TNT, plasticizers, dinitroluene).
[00012] In another embodiment, the present invention provides a system and method that converts NTO or other nitro-heterocylic insensitive munitions to mostly benign gaseous products (CO2 and N2) with a hydraulic retention time in the time scale of minutes by using a reduction step followed by an oxidation step. A first stage reduces NTO stoichiometrically to 3-amino-l,2,4-triazol-5-one (ATO) with the Fe n /Fe in containing mineral, green rust and the second stage converts ATO to CO2 and N2 with the
Mn Iv containing mineral, birnessite.
[00013] In another embodiment, the present invention provides a system and wherein NTO is reductively transformed stoichiometrically to the amine containing daughter product, ATO.
[00014] In another embodiment, the present invention provides a system and method wherein DNAN is reductively transformed to MENA.
[00015] In another embodiment, the present invention provides a system and wherein MENA is reductively transformed to DAAN.
[00016] In another embodiment, the present invention provides a system and wherein a complete to near complete abiotic reductive transformation of IMCs to reduced daughter products in a matter of minutes is achieved.
[00017] In another embodiment, the present invention provides a system and wherein NTO is transformed by a first stage of sequentially one or more packed bed reactors, the first stage reactors contain solid phase mineral materials, mineral-based electron donating materials, GR, ZVI or iron minerals with adsorbed Fe 2 + or combinations thereof and create an effluent of ATO. Also provided is a second stage of one or more reactors that receive the ATO effluent and the second stage reactors oxidize the ATO.
[00018] In another embodiment, the present invention provides a system and wherein one or more second stage reactors are continuously feed permanganate (MnO¾) that oxidize ATO (or other reduced munitions compounds) even faster than Mn02 and at the end of the reaction, MnO¾ forms Mn02.
[00019] In another embodiment, the present invention provides a system and wherein one or more reactors contain sand mixed with GR, ZVI or iron minerals with adsorbed Fe 2 + or combinations thereof and said second stage reactors contain sand mixed with MnO¾ or Mn02.
[00020] In another embodiment, the present invention provides a system and wherein Mn02 coated sand particles provide a lasting reservoir of the Mn02 oxidant in a packed bed reactor. [00021] In another embodiment, the present invention provides a system and wherein one or more second stage reactors contain a solid phase mineral oxidant.
[00022] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[00023] In the drawings, which are not necessarily drawn to scale, like numerals may describe substantially similar components throughout the several views. Like numerals having different letter suffixes may represent different instances of substantially similar components. The drawings illustrate generally, by way of example, but not by way of limitation, a detailed description of certain embodiments discussed in the present document.
[00024] Figure 1 illustrates the structures of NTO and ATO.
[00025] Figure 2A shows for DNAN the transformation of IMCs (0.5 mM) by GR at 10 g kg -1 solid to solution ratio at pH 8.4.
[00026] Figure 2B shows for NTO the transformation of IMCs (0.5 mM) by GR at 10 g kg "1 solid to solution ratio at pH 8.4.
[00027] Figure 3A shows, for the oxidation of DNAN and its daughter products, MENA and DAAN, a comparison of IMC and daughter product oxidation by birnessite (Mn02) at a SSR of 15 g kg -1 , pH 7, room temperature.
[00028] Figure 3B shows, for the oxidation of NTO and its daughter compound, ATO, a comparison of IMC and daughter product oxidation by birnessite (Mn02) at a SSR of 15 g kg -1 , pH 7, room temperature.
[00029] Figure 4 illustrates for one embodiment of the present invention a sequence of reactions with GR and Mn02 minerals, respectively.
[00030] Figure 5 illustrates for one embodiment of the present invention packed bed reactors for the reduction of NTO to ATO, and subsequent and oxidation of ATO to CO2 and
N 2 . DETAILED DESCRIPTION OF THE INVENTION
[00031] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a
representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed method, structure or system. Further, the terms and phrases used herein are not intended to be limiting, but rather to provide an understandable description of the invention.
[00032] In a preferred embodiment, the present invention recognizes that both DNAN and NTO may be susceptible to reduction by GR at 10 g kg -1 solid to solution ratio (SSR). The reaction of NTO with GR was faster and nearly completed within 10 minutes after reaction initiation as shown in Figures 2 A and 2B.
[00033] As shown in Figure 2B, NTO was reductively transformed stoichiometrically to the amine containing daughter product. Similarly, as shown in Figure 2A, DNAN was reductively transformed to MENA, which was then further reduced to DAAN over time. In the case of DNAN, the products, 2-methoxy-5-nitroaniline (MENA) and (DAAN), accumulated in high yields along with 4-methoxy-5-nitroaniline (iMENA), an isomer of MENA.
[00034] As is also shown in Figures 2A and 2B, the normalized absorbance and first derivative Fe-X-ray absorption near edge structure (Fe-XANES) spectra collected from reacted samples indicate oxidation of the GR to lepidocrocite ((gamma-Fe in O(OH))-like species during the reductive transformation of DNAN and NTO. This is more evident in the case of NTO as compared to DNAN. The Fe-XANES results show clear shift of oxidation state from Fe n /Fe in (green rust) to Fe in (lepidocrocite) upon reaction with IMCs.
[00035] Accordingly, in a preferred embodiment, a complete to near complete abiotic reductive transformation of IMCs to reduced daughter products in a matter of minutes is achieved by the present invention. While the reduced daughter products are not safe end products because many of them are also toxic compounds, such compounds are highly susceptible to oxidation in a matter of minutes with common, occurring manganese mineral, birnessite. [00036] DAAN and ATO were also found to be oxidized in less than 5 minutes with 15 g kg -1 solid to solution ratio (SSR) as shown in Figures 3A and 3B. It has also been found that ATO is mineralized to a large extent to benign gaseous end products (CO2 and N2) .
[00037] For one preferred embodiment, the present invention provides a sequence of reductive and oxidative reactions. One or more reactors packed with the reactive minerals GR and Mn02 are provided which can rapidly remediate NTO with cumulative hydraulic retention times of less than 10 minutes. The sequence of reaction is shown in Figure 4.
[00038] In another preferred embodiment, the packing in each reactor may contain minimally 20% mass to volume of the reactive minerals. The products of the reaction will be a mixture of mostly benign gasses. In one aspect, the gasses may be CO2 and N2.
[00039] In yet other embodiments of the present invention, benign urea is also formed in the aqueous phase. For these embodiments, the present invention is suited for treating NTO contaminated groundwater or munitions wastewater.
[00040] Figure 5 provides, for one embodiment of the present invention, an exemplary system 500 that may be used in the treatment of an IMC such as NTO. System 500 may include a first stage of one or more sequentially packed bed reactors 502. The first stage reactors may be filled with green rust mixed with sand 504 (for permeability). In yet other embodiments of the present invention, the first stage reactors may contain solid phase mineral material and/or mineral-based electron donating materials. Inlet 506 receives an IMC influent such as NTO which first flows past glass beads 508.
[00041] Effluent from reactor 502, which may be ATO, is sent to one or more packed bed reactors 510 comprising a second stage via pathway 509 through glass beads 512. Reactor 510 may be filled with birnessite (Mn0 2 ) mixed with sand 514. In yet other embodiments of the present invention, the second stage reactors may contain solid phase mineral oxidants. Effluent from reactor 510 is mainly benign gasses such as CO2 and N2.
[00042] In other embodiments, the sequentially connected reactors may contain other materials. For example, for the first stage reactors, instead of green rust, a precursor may be used such as zero valent iron (ZVI) which corrodes to green rust. Or, one reactor of the first stage may contain green rust and another reactor in the sequence may use a precursor such as ZVI. Another reactor in the sequence of the first stage may further contain iron minerals with adsorbed Fe 2 + . This material may also be provided for use with or as an alternative to green rust and ZVI. In other embodiments, the first stage reactors may contain GR, ZVI, iron minerals with adsorbed Fe 2+ or combinations thereof in one or more reactors of the first stage.
[00043] One or more of the second stage reactors may be operated by slowly and/or continuously feeding permanganate (MnO^) which is a powerful oxidant that can oxidize ATO (or other reduced munitions compounds) even faster than Μηθ2· At the end of the reaction, MnO¾ forms MnC>2 which would coat the sand particles and provide a lasting reservoir of the MnC>2 oxidant in a packed bed reactor.
[00044] While the foregoing written description enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The disclosure should therefore not be limited by the above-described embodiments, methods, and examples, but by all embodiments and methods within the scope and spirit of the disclosure.
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