HEAVY METAL ADSORBENT MATERIAL, PROCESSES OF MAKING THE SAME, AND METHODS OF SEPARATING HEAVY METALS FROM FLUIDS

DESCRIPTION OF THE INVENTION Cross-Reference to Related Applications

[001] This application claims the right of priority to, and hereby incorporates by reference in their entireties, the following prior-filed applications: U.S. Provisional Application No. 60/871 ,460, filed December 22, 2006; International Application No. PCT/US2007/071311 , filed June 15, 2007; and, U.S. Provisional Application No. 60/814,481 , filed June 16, 2006.

Field of the Invention

[002] Disclosed herein are granulated heavy metal adsorbent materials, their processes for synthesis using a natural diatomite feed material or diatomite powder, and methods of using the granulated heavy metal adsorbent materials to separate all or a portion of a heavy metal from a fluid.

Background of the Invention

[003] Mercury is a naturally occurring heavy metal found in rocks, soils, and crude oils, such as in regions of volcanic activity, and exists in three different forms: elemental (Hg ⁰ ), inorganic (such as Hg ² + and Hg ₂ ²⁺ ), and organic (or organomercurial compounds such as methyl mercury). Common sources of mercury contamination in air, water, sludge, sediment, and soil include fossil fuel combustion; production of chemicals like chlorine, caustic soda, cement, and lime; incineration of waste and sewage sludge; mining and beneficiation operations; and refining of crude oils. At high concentrations, mercury may become an environmental contaminant with possible toxic

effects on living organisms. For example, toxic levels of mercury may damage the kidneys, livers, intestines, and/or brain. Consequently, there is a need for techniques to remove mercury from sources that contain mercury and/or other heavy metals.

[004] One market for mercury removal is in hydrocarbon process applications. Agents used for the mercury removal may include catalyst materials and treated granular activated carbon. Such process technology may require performance at a large scale in order to be commercially successful. However, certain niche applications, such as, for example, offshore natural gas and gas liquids processing have a commercial need for a mercury adsorbent composition having a high mercury loading capacity and a fast mercury removal rate.

[005] Commercially available mercury removal technologies include: (a) activated carbon adsorption; (b) sulfur-impregnated activated carbon; (c) microemulsion liquid membranes; (d) ion exchange; and (e) colloidal precipitation. Mercury removal from those technologies may inefficiently remove mercury because of, for example, slow kinetics, poor selectivity for mercury, and/or low mercury loading capacity. Moreover, those technologies may be expensive because of waste disposal costs.

[006] Synthetic mesoporous silica has been evaluated for mercury removal ability including, for example, tetraethylorthosilicate and 3- mercaptopropyltrimethoxysilane that are co-condensed to form a surface- treated synthetic mesoporous silica material. See Brown et al., One-Step Synthesis of High Capacity Mesoporous Hg ²⁺ Adsorbents by Non-ionic Surfactant Assembly. Microporous and Mesoporous Materials, 41 -48 (2000).

U.S. Patent No. 6,326,326 discloses a mesoporous silica having thiol functional groups attached thereto. Although high mercury loading capacity is reported in these materials, the cost to synthesize them may be higher compared to naturally available porous silica such as diatomite. The complicated process to attach thiol functional groups to the synthetic mesoporous silica materials may also add further cost to the total production expense of making such mercury adsorbent products.

[007] Silica-based minerals, for example, northern Moroccan diatomite, have been used to remove mercury from aqueous mercury solutions. See Mazouak, A. et al., A New Adsorbent for the Efficient Elimination of Heavy Metals from Industrial Dismissal of Tetouan Area, International Journal of Environmental Studies, 4, 1 -6 (2001 ). In the Mazouak article, since no functional mercury removal group was attached to the diatomite surface, the treated waste product was chemically unstable because of the weak attraction between the absorbed mercury and the diatomite.

[008] Japanese Kokai Patent Application No. Hei 5[1993]-212241 discloses attaching a mercapto functional group to a substrate prepared from a mixture of silicon dioxide, titanium dioxide, activated clay, silica gel, diatomaceous earth, and perlite.

[009] Composite articles have been used to concentrate or remove mercury from gases and liquids. For example, U.S. Patent No. 3,961 ,031 discloses a method for removal of mercury contained in sulfur dioxide- containing gas by contacting the gas with an aqueous thiourea solution that optionally contains an acid at an acidity higher than one normally used to selectively absorb mercury in a vapor state.

[010] U.S. Patent Nos. 5,558,771 and 5,492,627 disclose composite articles for use in separating mercury from fluids, wherein the composite articles are directed to finely divided gold, optionally in combination with a tin salt, immobilized on the surface of inert substrates to adsorb elemental, ionic, and/or organic mercury.

[011] U.S. Patent No. 4,057,423 discloses a contact scrubbing technique to precipitate and remove heavy metals, such as mercury, contained in sulfuric acid.

[012] U.S. Patent Application Publication No. 2005/0204867 discloses a heavy metal adsorbent composition comprising natural diatomite in the form of siliceous frustules, wherein the composition is in the form of pellets.

[013] Environmental remedial applications for trapping heavy metals, including mercury, have not been sufficiently developed for use in commercial applications. The dominant mercury removal adsorbent material is activated carbon. However, none of the known environmental remedial applications and agents utilize granulated natural diatomite and an activating material that is used to activate the diatomite surface for rapidly and efficiently removing heavy metals like mercury and gold from fluids.

[014] A need, therefore, exists for a heavy metal adsorbent material capable of separating heavy metal from fluids. Moreover, a need exists for a material capable of adsorbing mercury from fluids.

SUMMARY OF THE INVENTION

[015] Disclosed herein is a granulated heavy metal adsorbent material comprising:

a) granulated diatomite; and b) at least one surface treatment agent capable of separating all or a portion of heavy metals in a fluid, such as an aqueous solution and an oily solution.

[016] There is also disclosed: a process for preparing a heavy metal adsorbent powder comprising: a) treating natural diatomite feed material with at least one surface treatment agent capable of separating all or a portion of heavy metals in a fluid in the presence of a solvent. [017] There is further disclosed a process for preparing a granulated heavy metal adsorbent material comprising: a) reacting a heavy metal adsorbent powder with at least one silicate, such as tetraethylorthosilicate, in the presence of a solvent, such as methanol; and b) contacting the powder with a plurality of sols comprising networks of oxides.

[018] Further disclosed herein is:

A method for separating heavy metal from a fluid comprising: a) contacting a fluid containing heavy metal with a sufficient amount of a granulated heavy metal adsorbent material to reduce the heavy metal level in said fluid. [019] In certain embodiments, the fluid may be an aqueous solution and an oily solution.

[020] Also disclosed herein are processes for the preparation of heavy metal adsorbent powders and granules. These processes do not require the use of solvents such as chloroform, thereby lowering production costs and reducing environmental impact.

[021] In one aspect, a process for preparing heavy metal adsorbent powders comprises:

(a) providing a natural diatomite feed material; and

(b) mixing the natural diatomite feed material with an aqueous solution comprising a surface agent capable of adsorbing heavy metals.

[022] In another aspect disclosed herein, a process for preparing heavy metal adsorbent granules comprises:

(a) providing diatomite powders;

(b) spraying the surface of the diatomite powders with a solution comprising at least one surface agent capable of adsorbing heavy metals and at least one granulating agent.

[023] In another embodiment disclosed herein, a process for producing heavy metal adsorbent granules comprises:

(a) providing a diatomite powder;

(b) contacting the diatomite powder with an aqueous solution comprising at least one surface agent capable of adsorbing heavy metals and at least one granulating agent.

[024] In another aspect disclosed herein, a two-step process for preparing heavy metal adsorbent granules comprises: (a) providing diatomite powders;

(b) spraying the surface of the diatomite powders with a solution comprising at least one surface agent capable of adsorbing heavy metals;

(c) granulating the resulting diatomite powders with at least one granulating agent.

BRIEF DESCRIPTION OF THE DRAWING [025] Figure 1 illustrates a graph depicting the mercury removal performance of heavy metal adsorbent powders prepared from different silane solutions.

DETAILED DESCRIPTION OF THE PRESENT INVENTION [026] One aspect disclosed herein relates to granulated heavy metal adsorbent materials treated with at least one surface treatment agent capable of separating all or a portion of heavy metals from a fluid. The granulated materials may be configured to separate gold and/or mercury from a fluid. Thus, in one embodiment, the materials may be granulated mercury adsorbent materials having the surfaces thereof treated with at least one surface treatment agent capable of separating mercury from a fluid. The surface-treated granulated diatomite, when brought into contact with a mercury-containing fluid, interacts with at least a portion of mercury in the fluid and the mercury adsorbs onto the granulated diatomite at the sites of the surface treatment agents.

[027] The granulated heavy metal adsorbent materials disclosed herein may have increased surface areas relative to heavy metal adsorbent

diatomite powders and pellets, such as, for example, the pellets disclosed in U.S. Patent Application Publication No. 2005/0204867. Accordingly, the granulated heavy metal adsorbent materials may contain more active sites capable of removing heavy metals from a fluid. The increase in active sites may also result in more efficient separation of the heavy metal.

[028] In some embodiments, the surface area of the granulated heavy metal adsorbent material may range from about 50 m ² /g to about 150 m ² /g, from about 80 m ² /g to about 120 m ² /g, and from about 95 m ² /g to about 105 m ² /g. In further embodiments, the surface area may be about 95 m ² /g, about 96 m ² /g, about 97 m ² /g, about 98 m ² /g, about 99 m ² /g, about 100 m ² /g, about 101 m ² /g, about 102 m ² /g, about 103 m ² /g, about 104 m ² /g, and about 105 m ² /g.

[029] In certain embodiments, the increased surface area results from a sol-gel derived porous silica structure that agglomerates diatomite powders. Moreover, the pores of the silica structure may provide pathways for heavy metals in a fluid to contact and adsorb onto the surface treatment agents of the adsorbent materials. The porous silica structure may be provided by a sol-gel reaction that binds particles together via a three- dimensional -[Si-O-Si]- cross-linking network.

[030] In one embodiment, the mercury removal rate of a granulated mercury adsorbent material as disclosed herein is at least about 90% in 10 minutes from a starting ionic mercury concentration of about 5.52 ppb in an aqueous solution by passing through a one-inch diameter and 3.5 inch long column packed with about 23 g of the granulated mercury adsorbent material at 20 ml/min flow rate. In further embodiments, the mercury removal rate may

be at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, and at least about 99%. In yet another embodiment, the mercury removal rate may range from 90% to about 100%.

[031 ] The granule size of the granulated heavy metal adsorbent material may be adjusted to a suitable distribution using techniques known in the art. For example, the granulated heavy metal adsorbent material may undergo mechanical separations to adjust the granule size distribution. Numerous separations are readily available to the skilled artisan including, without limitation, screening, extrusion, triboelectric separation, liquid classification, and air classification.

[032] In one embodiment, the size of the granulated material may be about 10 mm or less. In further embodiments, the granule size may range from about 1 mm to about 10 mm, from about 4 mm to about 10 mm, from about 5 mm to about 10 mm, from about 2 mm to about 8 mm, from about 2 mm to about 4 mm, from about 2.5 mm to about 3.5 mm, from about 1 mm to about 5 mm, from about 1.2 mm to about 3.5 mm, and from about 1.2 mm to about 2 mm. In yet another embodiment, the size of the granulated materials may be at least about 0.5 mm. In further embodiments, the size of the granulated materials may range from about 0.5 mm to about 1 mm, from about 0.6 mm to about 0.85 mm, from about 0.6 mm to about 1.2 mm, and from about 0.85 mm to about 1.2 mm.

[033] Another aspect disclosed herein relates to methods for processing the granulated adsorbent material in accordance with the subject

matter disclosed herein. In certain embodiments, a sol-gel reaction may be utilized to granulate heavy metal adsorbent powders as disclosed herein.

[034] According to one embodiment, a granulated heavy metal adsorbent powder may first be prepared by treating natural diatomite feed material with at least one surface treatment agent capable of removing heavy metals and is subsequently agglomerated into a granulated material. In one embodiment, the surface treatment agents capable of removing heavy metals can be chosen from silanes of formula (I):

(R-(CH ₂ )n)x-Si-R' _4-x

(I) wherein R is, independently, chosen from non-hydrolyzable organofunctional groups capable of removing heavy metals including mercapto (-SH), hydroselenide (-SeH), hydrotelluride (-TeH), disulfide (-S-S-), diselenide (-Se- Se-), and ditelluride (-Te-Te-);

R' is, independently, chosen from hydrolyzable groups including hydrogen, alkoxy, acyloxy, halogen, and acetoxy; x ranges from 1 to 3; and n ranges from 1 to 20.

[035] Silanol (- Si-OH) groups may occur on the natural diatomite surface. When those silanol groups react with organosilanes such as the surface treatment agents disclosed herein, the functional groups at the terminal end of the organosilanes may attach to the surface of the diatomite to form surface-treated materials. In one embodiment, the surface treatment agent is gamma-mercaptopropylthmethoxy silane. A suitable gamma- mercaptopropyltrimethoxy silane that may be used in the embodiments

disclosed herein is, for example, SILQUEST A-189 (GE Silicones-OSi Specialties; Endicott, N.Y., U.S.A.).

[036] In one embodiment, the ratio by weight of the at least one surface treatment agent to diatomite in the reacting step may be about 0.1 part surface treatment agent to about 1 part diatomite. In further embodiments, the ratio by weight may be about 1 part surface treatment agent to about 1 part diatomite, about 0.5 part surface treatment agent to about 1 part diatomite, about 0.1 part surface treatment agent to about 2 parts diatomite, about 0.3 part surface treatment agent to about 1 part diatomite, and about 0.8 part surface treatment agent to about 1 part diatomite.

[037] Additionally, the reacting step may take place in a solvent suitable for an organosilane. In one embodiment, the solvent is not an alcohol. In a further embodiment, the solvent is non-aqueous. In yet another embodiment, the solvent is chloroform. Other exemplary non-alcoholic solvents include, for example and without limitation, formaldehyde, furfural, acrolein, n-hexyl acetate, 2-hydroxypropanoic acid, formic acid, acetic acid, dimethylacetamide, pentane, hexane, dipentane, heptane, benzene, o-xylene, toluene, catechol, hydroquinone xylene, p-xylene, m-xylene, and ethylbenzon. In one embodiment, the ratio by weight of the solvent to the diatomite ratio may range from about 1 part solvent to about 2 parts diatomite. In further embodiments, the ratio may range from about 1 part solvent to about 1 part diatomite, or from about 2 parts solvent to about 1 part diatomite. When the ratio of the at least one surface treatment agent, such as gamma- mercaptopropyltrimethoxy silane, to diatomite is about 0.1 part surface treatment agent to about 1 part diatomite, the ratio of solvent, such as

chloroform, to diatomite may be about 1 part solvent to 2 parts diatomite. In certain embodiments, the reaction may take place in a sealed chemical resistant vessel, such as glass, TEFLON, or stainless steel, with sufficient agitation at room temperature for a time period ranging from 24 hours to 96 hours.

[038] Suitable natural diatomite feed materials utilized by the embodiments disclosed herein may be chosen from commercially available diatomite products, for example, CELITE 500, CELITE S, and CELITE NPP (World Minerals Inc.; Santa Barbara, CA, USA); and FN-1 , FN-2, and FN-6 (EaglePicher Filtration & Minerals, Inc.; Reno, NV, USA).

[039] The natural diatomite feed material may have a particle size distribution having a dio of about 5 μm, d ₅ o of about 27 μm and a dgo of about 82 μm. As used herein, the term "dio" refers to the particle size for which 10 percent of the volume is smaller than the indicated size, the term "d ₅ o" refers to the particle size for which 50 percent of the volume is smaller than the indicated size, and the term "dgo" refers to the particle size for which 90 percent of the volume is smaller than the indicated size. In further embodiments, the dio may range from about 1 μm to about 15 μm, from about 3 μm to about 10 μm, and from about 3 μm to about 5 μm. The d ₅ o may range from about 20 μm to about 40 μm, from about 20 μm to about 30 μm, and from about 24 μm to about 28 μm. The dgo may range from about 60 μm to about 120 μm, from about 70 μm to about 100 μm, and from about 80 μm to about 85 μm.

[040] The treating step may take place in a sealed chemical resistant vessel with sufficient agitation at room temperature (such as at about

20°C to about 23°C). The treating step may take about 24 hours or more, or in certain embodiments, may take place for about 96 hours or less. The reaction may proceed to completion, to equilibrium, or to any point before equilibrium or completion. In another embodiment, the vessel is lined with a chemical resistant material. In another embodiment, the silinization reaction in the treating step may take place by spraying a silane-containing solution onto the natural diatomite surface. In one embodiment, the reaction may take place inside a mixer or turbulizer.

[041] Optionally, the heavy metal adsorbent powder may include increased surface silanol groups relative to natural diatomite. As disclosed herein, increasing the surface silanol groups may increase the reaction sites wherein the heavy metal adsorbent organofunctional group attaches to the diatomite. Increasing surface silanol groups of the heavy metal adsorbent powder may be accomplished by hydrating the natural diatomite feed material, such as, for example, by mixing the natural diatomite feed material with 5% to 20% deionized water. In one embodiment, natural diatomite may be dehydrated to decrease the number of silanol groups on its surface.

[042] The intermediate powdered product can undergo intermediate processing steps before granulation. For example, the intermediate diatomite powder may be filtered, dried, and/or dispersed using techniques known in the art before it is agglomerated into granules. Suitable filtering techniques may be chosen from cake filtering, clarifying filter, and crossflow filtering. The intermediate powder product may be air dried or commercially dried using, for example, dryers chosen from tray dryers, screen-conveyor dryers, tower dryers, screw-conveyor dryers, fluid bed dryers, and flash dryers.

[043] In a further embodiment, the surface treatment agent may undergo hydrolysis and condensation reactions to attach a silica-based oligomer to the surface of the natural diatomite. As used herein, the term "oligomer" refers to a pre-polymer wherein the compound contains about ten or fewer repeating units of a monomer and is interchangeable with the term "telomer" or "pre-polymer." Thus, a silica-based oligomer may have about ten or fewer repeating units of the monomer "-Si-O-." Moreover, a mercury adsorbent organofunctional group may be attached to at least one of the Si elements in the oligomer. As disclosed herein, suitable heavy metal adsorbent organofunctional groups may include mercapto, hydroselenide, hydrotelluhde, disulfide, diselenide, and ditelluride. In a further embodiment, a heavy metal adsorbent organofunctional group is attached to each Si element in the silica-based oligomer.

[044] An exemplary reaction scheme utilizing both hydrolysis and condensation reactions for attaching a heavy metal adsorbent silica-based oligomer to the surface of natural diatomite is provided. Scheme A hydrolyzes a surface treatment agent, in this instance a mercapto-containing silane, using techniques and process conditions known in the art. For example, the hydrolysis reaction of Scheme A takes place in the presence of water. The water may be chosen from deionized water or ultra pure water. In one embodiment, the water may be an amount sufficient to initiate and/or drive the reaction under controlled conditions. In another embodiment, the source of the water may be residual water on the surface of the diatomite feed material. HS-(CH ₂ )n-Si-R' ₃ + 3H ₂ O ► HS-(CH ₂ ) _n -Si-(OH) ₃ + 3R ¹ OH

SCHEME A

wherein n ranges from 1 to 20; and

R' is, independently, chosen from hydrolyzable groups such as hydrogen, alkoxy, acyloxy, halogen, and acetoxy.

[045] As used herein, the term "alkoxy" refers to a functional group having the formula -OR. The term "acyloxy" refers to a functional group having the formula -R-CO2. The term "halogen" refers to elements of Group 17 of the periodic table including fluorine, bromine, iodine, chlorine, and astatine. The term " acetyl" refers to a functional group having the formula -RCOCH ₃ . The R group in each of alkoxy, acyloxy, and acetoxy may be a hydrocarbon chain including unsubstituted alkyls, substituted alkyls, unsubstituted alkenyls, substituted alkenyls, unsubstituted alkynyls, substituted aryls, unsubstituted aryls, and substituted alkynyls. Any one of R may independently be substituted with at least one group chosen from alkyl, alkenyl, alkynyl, aryl, ketone, aldehyde, and halogen groups.

[046] Scheme B prepolymehzes the hydrolyzed silane from Scheme A through a self-condensation reaction, thereby preparing an organofunctional silanol compound. The silanol (-Si-OH) groups in the terminal position provide reactive sites for additional reactions such as condensation reactions. In one embodiment, "n" ranges from 1 to 20.

SH SH SH HS-(CH ₂ ) _n -Si-(OH) ₃ + 2(HS-(CH ₂ ) _n -Si-(OH) ₃ ) ► HO-Si-O-Si-O-Si-OH + 3H ₂ O

OH OH OH

SCHEME B

[047] Scheme C provides a condensation reaction with a suitable substrate, in this instance, the surface of the natural diatomite feed material. As disclosed herein, the surface of the diatomite includes silanol (-Si-OH) groups wherein the hydroxyl group is reactive with the terminal positions of the pre-polymer silanol of Scheme B. Under acidic or basic conditions, the condensation reaction may produce siloxane bonds and eliminate water, thereby attaching the resulting siloxane moiety to the surface of the diatomite via the hydroxyl group.

[048] In an embodiment where the condensation reaction, Scheme C, takes place in acidic conditions, an acidic solution comprising about 1 % or less acid may be added to the silanol. Examples of acids that can be used include protic acids such as hydrochloric acid, sulfuric acid, trifluoroacetic acid, thfluoromethanesulfonic acid, acetic acid and acrylic acid, and Lewis acids such as iron chloride, aluminum chloride, lead chloride and titanium chloride. The acids may be added in a drop-wise fashion. Scheme C may optionally include an organic solvent. Although the organic solvent may not participate directly in the reaction, diluting the reaction system improves the mixing of the aqueous phase and may improve the reaction rate. Examples of organic solvents include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, benzene, toluene, and xylene.

[049] The heavy metal adsorbent siloxane group may undergo further reactions to replace any remaining reactive hydroxyl groups bonded to a silicon element with, for example, organically non-reactive groups such as alkyl groups, cycloalkyl groups, and phenyl groups.

SH SH SH

HO-Si-O-Si-O-Si-OH SH SH SH

OH OH OH ^ HO-Si-O-Si-O-Si-OH OH OH OH O O O +3H ₂ O

Diatomite Substrate Diatomite Substrate

SCHEME C

[050] Thus, the intermediate powder product may be chosen from diatomite powders having a heavy adsorbent functional group attached directly to a hydroxyl group on the diatomite's surface or diatomite powders having a silica-based heavy metal adsorbent group attached to a hydroxyl group on the diatomite's surface.

[051] The intermediate powder product, which is the heavy metal adsorbent powder, may be further treated in a sol-gel reaction with at least one granulating agent, such as a silicate. The sol-gel reaction creates a porous three-dimensional cross-linking network of metal hydroxide bonds (for example, siloxane bonds) that may agglomerate the powders into a granulated product as disclosed herein. The pores of the network may also provide pathways for heavy metals to adsorb onto the adsorbent active sites on the granulated product. The adsorbent active sites comprise a non- hydrolyzable organofunctional group capable of removing the heavy metals. Exemplary groups include mercapto, hydroselenide, hydrotelluride, disulfide, diselenide, and ditelluride.

[052] In one embodiment, the heavy metal adsorbent powders are contacted with a plurality of sols to agglomerate the powders into granules.

The plurality of sols may polymerize to grow a three-dimensional (3-D) network of metal hydroxide bonds to connect the intermediate powder products into granular sized agglomerations. A plurality of sols may be prepared by mixing at least one silicate with an alcohol. As used herein, the term "sol" or "sols" refers to small particles of three-dimensional cross-linking networks of oxides. The silicate undergoes hydrolysis and condensation reactions to create the plurality of sols. In one embodiment, the sols are silica-based. In further embodiments, the sols are titania-based or zirconia- based. The sols may subsequently be added to a heavy metal adsorbent powder to agglomerate the powder, thus forming a granulated heavy metal adsorbent material.

[053] Silicates that may be used according to certain embodiments may be chosen from metal alkoxide sol-gel precursors such as tetramethylorthosilicate (Si(OCH ₃ ) ₄ ), tetraethylorthosilicate (Si(OCH ₂ CH ₃ ) ₄ ), sodium silicate, and potassium silicate. In another embodiment, the silicate may be any silicate of formula (II):

Si(ORi)(OR ₂ )(OR ₃ )(OR ₄ )

(II) wherein Ri, R ₂ , R ₃ , and R ₄ , which may be identical or different, are independently chosen from hydrogen, unsubstituted alkyls, substituted alkyls, unsubstituted alkenyls, substituted alkenyls, unsubstituted alkynyls, substituted aryls, unsubstituted aryls, and substituted alkynyls.

[054] In one embodiment, Ri, R ₂ , R ₃ , and R ₄ are the same. In another embodiment, Ri, R ₂ , and R ₃ are the same, and R ₄ is different. In

another embodiment, Ri and R2 are the same, and R3 and R ₄ are different. In a further embodiment, where R3 and R ₄ are different from Ri and R2, R3 and R ₄ may be the same or different from each other. In a further embodiment, all of Ri, R2, R3, and R ₄ are different.

[055] As used herein, the term "alkyl" refers to lower alkyl groups having ten or less carbons. Thus, an alkyl group may be chosen from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. As used herein, the term "alkenyl" refers to lower alkenyl groups having at least one double bond. The alkenyl group may have ten or less carbons. As used herein, the term "alkynyl" refers to a lower alkynyl groups having at least one triple bond. The alkynyl may have ten or less carbons.

[056] Any one of Ri, R2, R3, and R ₄ may, independently, be substituted with at least one group chosen from alkyl, alkenyl, alkynyl, aryl, ketone, aldehyde, and halogen groups.

[057] In one embodiment, the reaction to produce the plurality of sols takes place in an alcohol solvent. The alcohol solvent may be chosen from lower alkyl alcohol solvents. Exemplary lower alkyl alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, /-butanol, and f-butanol. Preparation of the sols may be facilitated by mixing the silicate and alcohol solution at room temperature (about 20 ⁰ C to about 23 ⁰ C). In another embodiment, the mixing may take place when the solution is at an elevated temperature. In further embodiments, the elevated temperature may range from about 25 ⁰ C to about 100 ⁰ C, from about 40 ⁰ C to about 80 ⁰ C, from about 55 ⁰ C to about 75 ⁰ C, and from about 60 ⁰ C to about 70 ⁰ C. In one embodiment, the elevated temperature may be about 70 ⁰ C.

[058] Preparation of the sols may be facilitated by the addition of at least one catalyst. Numerous catalysts are known to the skilled artisan to increase the rate of a sol-gel reaction. In one embodiment, for example, the catalyst may be chosen from protic acids. Exemplary protic acids include HCI, HBr, and HF. In yet another embodiment, the catalyst may be chosen from bases, for example, ammonia.

[059] The sols may be mixed with the heavy metal adsorbent powder to granulate the powder and form a granulated heavy metal adsorbent material. In one embodiment, the sols may be slowly added to the powder. In yet another embodiment, the sols may be mixed directly with the powder in one step. Moreover, the solvent may remain within the pores of the three- dimensional network creating a gel. The granulated mercury adsorbent material may then be dried to evacuate the solvent from the pores.

[060] In one embodiment, the sols are bonded to the surface of the diatomite via a -Si-O-Si bond. In yet another embodiment, the sols encapsulate the diatomite.

[061] The granulated heavy metal adsorbent material may be separated into a desired granule size before the gelation or cross-linking. As used herein, the terms "gel", "gelation", "gelled", or "gelling" refer to the point wherein the sols form a cross-linking structure, which may be known as an alcogel, that contains both a liquid part and a solid part. In the structure, the liquid part is the solvent, and the solid part is the three-dimensional cross- linking network of linked oxides. In another embodiment, the granulated mercury adsorbent material is separated into a desired granule size after

gelation. Suitable separating techniques include screening, extrusion, triboelecthc separation, liquid classification, and air classification.

[062] In the sol-gel reaction, the growth of the three-dimensional cross-linking network of oxides may continue for a period of time. In one embodiment, the granulated mercury adsorbent material may be soaked in a mixture of alcohol and water to facilitate the growth of the cross-linking network. The pH of the mixture may be slightly basic, for example, ranging from about 8 to about 9. The gelation may also be facilitated by drying the granulated mercury adsorbent material. A drying oven heated to a temperature greater than room temperature may be used to facilitate the cross-linking network growth.

[063] The alcohol solvent may be evaporated from the granulated heavy metal adsorbent material using a variety of techniques. For example, the alcohol may be removed with a solvent, or the granulated material may undergo supercritical CO ₂ drying.

[064] In yet another embodiment, the sol-gel reactants may be mixed directly with the heavy metal adsorbent powder to form a granulated heavy metal adsorbent material. Thus, at least one silicate, alcohol solvent, the optional catalyst, and the heavy metal adsorbent powder may be mixed together in a one-pot reaction. The reactants may be added together simultaneously or sequentially. The liquid reagents such as the catalyst may be added in a dropwise fashion.

[065] In another embodiment of the processes disclosed herein, the granulated adsorbent product may be synthesized without first preparing an intermediate powder product or a plurality of sols. For example, a one-pot

approach to synthesis may comprise mixing together a feed material comprising natural diatomite, a heavy metal adsorbent organofunctional group-containing reagent, at least one silicate in an alcohol solvent, and optionally a catalyst. The reactants may be added in a single step or sequentially. The liquid reagents may be added in a dropwise fashion.

[066] The one-pot synthesis may further comprise mixing the reagents at a temperature above ambient temperature to facilitate the growth of the cross-linked network. For example, the temperature of the reaction mixture may be raised to and maintained at a temperature ranging from about 25 ⁰ C to about 100 ⁰ C, from about 40 ⁰ C to about 80 ⁰ C, from about 55 ⁰ C to about 75 ⁰ C, and from about 60 ⁰ C to about 70 ⁰ C. In a further embodiment, the elevated reaction mixture temperature may be about 70 ⁰ C.

[067] In another aspect, a process for preparing heavy metal adsorbent granules without first treating the natural diatomite material with a solvent, such as chloroform, is disclosed. A natural diatomite powder may be treated in a sol-gel reaction with a solution comprising at least one granulating agent, such as a silicate, and at least one surface agent capable of adsorbing heavy metals. The solution excludes solvents such as chloroform, formaldehyde, furfural, acrolein, n-hexyl acetate, 2-hydroxypropanoic acid, formic acid, acetic acid, dimethylacetamide, pentane, hexane, dipentane, heptane, benzene, o-xylene, toluene, catechol, hydroquinone xylene, p- xylene, m-xylene, and ethylbenzon.

[068] The concentration of the heavy metal adsorbent agent in the granulating solution may range from about 0.1 % to about 10%, for example from about 2% to about 8% or from about 4% to about 6%, by weight relative

to the total weight of the solution. In certain embodiments, the concentration of the heavy metal adsorbent in the granulating solution may comprise about 1 %, about 3%, about 5%, about 7%, or about 10%, by weight relative to the total weight of the solution.

[069] In a further aspect, the step of treating the natural diatomite feed material may comprise spraying the granulating solution onto the surface of the feed material. Sprays comprising particles of the at least one surface treatment agent capable of removing heavy metals may be produced by nozzles and other atomizing systems known in the art. Suitable equipment includes, for example, pressure nozzles, two-fluid nozzles, rotary devices such as spinning cups, disks, or coned wheels, hollow cones, whirl chamber, grooved cone, solid cone, fan spray, dual orifice nozzles, poppet nozzle, spill nozzle, and sonic atomizers. The diameter of the particles in the spray may range from about 5000 μm or less, for example from about 3000 μm or less, from about 1500 μm or less, or from about 750 μm or less.

[070] Selection of the spray producing processing equipment may impact the size of the spray particles. For example, if the equipment is a liquid pressure spray nozzle, then the particle size may range from about 100 μm to about 5000 μm. If the equipment is a gas-atomizing spray nozzle, then the spray particle size may range from about 1 μm to about 100 μm. If the spray is produced by bubbling a gas through the solution, then the spray particle size may range from about 20 μm to about 1000 μm. If the spray is produced by annular two-phase flow, then the spray particle size may range from about 10 μm to about 2000 μm.

[071 ] In another embodiment, the surface of the natural diatomite feed material may first be sprayed with a solution comprising at least one surface agent capable of adsorbing heavy metals, and the resulting powder may be agglomerated into granules with at least one granulating agent. In certain embodiments, the granulating agent may be tetraethylorthosilicate.

[072] The heavy metal adsorbent granules prepared as disclosed herein may have surface areas ranging from about 50 m ² /g to about 150 m ² /g, such as from about 80 m ² /g to about 120 m ² /g, or from about 95 m ² /g to about 105 m ² /g. In certain embodiments, the surface area may be about 95 m ² /g, 96 m ² /g, about 97 m ² /g, about 98 m ² /g, about 99 m ² /g, about 100 m ² /g, about 101 m ² /g, about 102 m ² /g, about 103 m ² /g , about 104 m ² /g , or about 105 m ² /g. In certain embodiments, the particle size of the granules may range from about 1 mm to about 10 mm. The particle size may be about 8 mm or less, about 5 mm or less, or about 3 mm or less.

[073] Another aspect disclosed herein relates to processes for preparing a heavy metal adsorbent powder. In one embodiment, the process may comprise treating a natural diatomite feed material with an aqueous solution comprising at least one surface treatment agent capable of removing heavy metals. Moreover, this process disclosed herein does not require the use of solvents, such as chloroform. Other exemplary solvents that are not required according to certain embodiments disclosed herein include formaldehyde, furfural, acrolein, n-hexyl acetate, 2-hydroxypropanoic acid, formic acid, acetic acid, dimethylacetamide, pentane, hexane, dipentane, heptane, benzene, o-xylene, toluene, catechol, hydroquinone xylene, p- xylene, m-xylene, and ethylbenzon. Consequently, equipment and

processing costs associated with the use of such solvents may be decreased along with any risk of environment damage caused by leaks.

[074] The natural diatomite feed material disclosed herein may be chosen from commercially available diatomite products. For example, suitable natural diatomite feed materials utilized herein may be chosen from CELITE 500, CELITE S, CELITE NPP, CHROMOSORB P, CHROMOSORB A, CHROMOSORB W, and CHROMOSORB G (World Minerals Inc.; Santa Barbara, California, U.S.A.); and FN-1 , FN-2, and FN-6 (EaglePicher Filtration & Minerals, Inc.; Reno, Nevada, U.S.A.). The natural diatomite feed material may also be material that has not undergone any or all the processing required for commercial sales. Thus, the natural diatomite feed material may be freshly mined saltwater or freshwater diatomite or aged saltwater or freshwater diatomite. In a further embodiment, the feed material may be a combination of any of the foregoing.

[075] The natural diatomite feed material may be chosen based upon its particle size distribution. In some embodiments, the dio may range from about 1 μm to about 15 μm, such as from about 3 μm to about 10 μm or from about 3 μm to about 5 μm. The d ₅ o may range from about 20 μm to about 40 μm, such as from about 20 μm to about 30 μm or from about 24 μm to about 28 μm. The dgo may range from about 60 μm to about 120 μm, such as from about 70 μm to about 1000 μm or from about 80 μm to about 85 μm. In one embodiment, the natural diatomite feed material may have a particle size distribution having a dio of about 5 μm, a d ₅ o of about 27 μm, and a dgo of about 82 μm.

[076] The concentration of the at least one surface treatment agent in the aqueous solution may range from about 0.1 % to about 10%, such as from about 2% to about 8% or from about 4% to about 6%, by weight relative to the total weight of the solution. In specific embodiments, the concentration may comprise about 1 %, about 3%, about 5%, about 7%, or about 10%, by weight relative to the total weight of the solution.

[077] In one embodiment, the step of treating the natural diatomite feed material may comprise mixing the solution with the natural diatomite feed material for a sufficient period of time to attach the at least one surface treatment agent to the surface of the diatomite feed material. The step of mixing may further comprise agitating the mixture of solution and diatomite feed material at room temperature, such as a temperature ranging from about 20 ⁰ C to about 23 ⁰ C. In a further embodiment, the step of mixing utilizes a dry mixer wherein the mass of the dry ingredients, such as the diatomite feed material, exceeds the amount of the wet ingredients. In certain embodiments, there is no need to subsequently filter the adsorbent powder from the remaining liquid ingredients. Suitable mixers are known to those skilled in the art and may include tumblers, ribbon mixers, vertical screw mixers, Muller mixers, twin rotors, single rotors, turbine mixers, shell, internal device rotors, V-blenders, HENSCHEL mixers, LITTLEFORD LODIGE mixers, and the like. Additionally, the aqueous solution may be added to the dry ingredients in the mixer as a spray.

[078] The processes disclosed herein may further comprise hydrating the natural diatomite feed material. Hydrating the natural diatomite feed material increases the surface silanol groups, thereby increasing the reaction

sites wherein the heavy metal adsorbent organofunctional groups may attach to the diatomite surface. In one embodiment, the step of hydrating comprises mixing the natural diatomite feed material with about 5% to about 20% deionized water.

[079] In further embodiments, the processes may comprise dehydrating the natural diatomite feed material to decrease the number of silanol groups on its surface.

[080] The processes may also comprise processing steps useful in preparing a finished powder product. For example, the diatomite powder may be dried and/or dispersed using techniques known in the art. The powder product may be air dried or commercially dried using, for example, dryers chosen from tray dryers, screen-conveyor dryers, tower dryers, screw- conveyor dryers, fluid bed dryers, and flash dryers.

[081] Yet another aspect disclosed herein relates to methods for separating heavy metals from fluids. One embodiment comprises contacting a fluid containing at least one heavy metal with a sufficient amount of granulated heavy metal adsorbent material as disclosed herein. In one embodiment, the fluid may contain mercury, such as covalently bonded mercury, elemental mercury, and/or ionic mercury. Covalently bonded mercury and elemental mercury may be converted to ionic mercury for use in the methods disclosed herein.

[082] One embodiment of the methods disclosed herein comprises a batch adsorption process, wherein a fluid containing at least one heavy metal is contacted with a sufficient amount of granulated heavy metal adsorbent material to separate all or a portion of the heavy metal from the fluid. The

resulting solution may be mixed continuously, periodically, or intermittently to facilitate contact between the granulated material and the fluid. As used herein, the term "batch" denotes a system wherein the fluid containing at least one heavy metal is charged into the system at the beginning of the process and the decontaminated fluid is removed sometime later. In certain embodiments, no additional fluid crosses into the system between the time the fluid containing at least one heavy metal is charged and the time the decontaminated fluid is removed. After the decontaminated fluid is removed, it may be filtered to separate any granulated heavy metal adsorbent materials contained therein.

[083] A conventional fixed bed column filtration process may also be used to separate heavy metal from a fluid containing at least one heavy metal. By passing the fluid through a column packed with the granulated heavy metal adsorbent material, the heavy metal concentration may be reduced. In certain embodiments, at least two columns may be used depending on the starting heavy metal concentration and the desired heavy metal discharging concentration.

[084] In one embodiment, at least two columns are utilized in a parallel fashion wherein the fluid is split into at least two streams. Using at least two parallel columns may allow one column to be removed from service, for example, for routine maintenance, to replace spent granulated heavy metal adsorbent material with fresh granulated heavy metal adsorbent material, and/or for repair work.

[085] In another embodiment, the heavy metal adsorbent material disclosed herein may be used in combination with other known techniques for

separating heavy metal. A fluid may undergo a less efficient heavy metal removal technique followed by a final step of contacting the fluid with the granulated heavy metal adsorbent material in accordance with the embodiments disclosed herein. For example, in one embodiment, the fluid may pass through a filtration column packed with activated carbon adsorbents to separate a portion of the heavy metal from the fluid. Then, the fluid may pass through a final filtration column containing the granulated heavy metal adsorbent material disclosed herein to separate all or a portion of the remaining heavy metal from the fluid.

[086] Examples of applications contemplated for the granulated mercury adsorbent materials made from diatomite disclosed herein include:

(a) mercury control in the chemical production process to protect equipment, catalysts, and systems;

(b) production process to meet a finished product specification;

(c) medical, municipal, and hazardous waste incinerators;

(d) chloro-alkali production;

(e) crude oil and other hydrocarbon liquids production;

(f) cement production;

(g) mercury removal in environmental remediation processes; (h) removal of mercury in water treatment systems contaminated by dental amalgams;

(i) treatment of mercury-contaminated radioactive liquid waste; (j) continuous mercury emission-monitoring devices with a reactive trap filter media to trap mercury in various forms; (k) mercury emissions control in waste treatment process; and

(I) gas phase heavy metal removal.

[087] Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained herein. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.

[088] Notwithstanding that the numerical ranges and parameters setting forth the broad scope are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[089] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein.

EXAMPLES Materials and Methods

[090] An aqueous solution containing ionic mercury can be prepared by spiking 1 ,000,000 μ/L or ppb (parts per billion) mercury Atomic

Absorption (AA) Standard solution into the deionized (Dl) water. Cold Vapor Atomic Absorption (CVAA) is used to determine the mercury concentration to a detection limit of 0.5 ppb. Example 1 - Mercury Adsorbent Powder:

[091] A natural diatomite product was used as the feed material to prepare a mercury adsorbent powder product. This feed material had a particle size distribution (PSD) ranging from 5 μm (dio, defined as the size for which 10 percent of the volume is smaller than the indicated size) to 82 μm (dgo, defined as the size for which 90 percent of the volume is smaller than the indicated size). 100 g of the feed material was mixed with 100 g of SILQUEST A-189 gamma-mercaptopropylthmethoxy silane and 1800 ml of chloroform in a 4000 ml glass flask covered with watch glass. After mixing for 4 days at room temperature on a magnetic stirrer, the slurry was washed with 500 ml of chloroform and filtered through a Buchner funnel with a #2 Whatman filter paper. The separated solid was placed in a glass tray and was air-dried overnight. This procedure was repeated several times to make enough products for testing. The specific surface area of the powder product was measured and is shown in Table 1.

Example 2 - Granular Mercury Adsorbent Material:

[092] 100 ml of tetraethylorthosilicate was mixed with the same volume of methanol (100 ml) in an Erlenmeyer flask covered with plastic wrap. After one hour of mixing at 70 ⁰ C, 64 ml of deionized (Dl) water and 3ml of 0.2N HCI were added to the solution. The mixed solution was stirred in an Erlenmeyer flask covered with plastic wrap for two hours to form sols. The

sols were slowly added to a mixer with 124 g of the high efficient mercury adsorbent powder of Example 1. After the particles agglomerated, the granules were screened through a top metal screen of ASTM Number 6 with a 3.35 mm opening and a bottom metal screen of ASTM Number 16 with a 1.18 mm opening. The screened granular product was then placed in a vacuum drying oven at 65°C where the sols gelled in several hours. After overnight drying at 65°C for water and organic solvent evaporation, a granular product with a granular size ranging from 1.18 mm to 3.35 mm was obtained. This procedure was repeated several times to make enough products for additional testing. The specific surface area was measured and is provided in Table 1.

Comparative Example 3 - CHROMOSORB P Pellets:

[093] A commercially available fixed bed media product, CHROMOSORB P, made from natural diatomite and clay, was used as the feed material. 300 g of CHROMOSORB P with granular size between 2.00 mm (ASTM Number 10) and 1.18 mm (ASTM Number 16) was mixed with 100 g of SILQUEST A-189 gamma-mercaptopropylthmethoxy silane and 1800 ml of chloroform in a sealed 4000 ml glass flask. After mixing on a shaker at 200 rpm for 4 days at room temperature (approximately 20 ⁰ C - 23°C), the solution was washed with 500 ml of chloroform and filtered through a Buchner funnel with a #2 Whatman filter paper. The separated solid was placed in a glass tray and was air-dried overnight. This procedure was repeated several times to make enough products for testing. The specific surface area of this product was measured and is shown in Table 1.

Table 1. Com arison of Surface Area of Mercur Adsorbent Com ositions

Example 4:

[094] About 23 g of the product of Example 2 was packed in a 3.5- inch long plastic column with 1 -inch diameter. An aqueous solution containing 5.52 ppb ionic mercury prepared from Atomic Absorption (AA) Standard Solution was pumped into the column at a flow rate of 20 ml/min. The residence time at this flow rate was about one minute and 47 seconds. The discharge solution was collected at the end of the column every 10 minutes for mercury analysis using the Cold Vapor Atomic Absorption (CVAA). No mercury was detected at the detection limit of the instrument of 0.5 ppb (>90.9% removal) during the 60-minute test period as shown in Table 2.

Comparative Example 5:

[095] 27 g of the product of Example 3 was packed in a 3.5-inch long plastic column with 1-inch diameter. An aqueous solution containing 5.52 ppb ionic mercury prepared from Atomic Absorption (AA) Standard Solution was pumped into the column at a flow rate of 20 ml/min. The residence time at this flow rate was about one minute and 52 seconds. The discharge solution was collected at the end of the column every 10 minutes for mercury analysis using the Cold Vapor Atomic Absorption (CVAA). The final mercury concentration after treatment was measured to be between 0.96 to 0.77 ppb (82.6 to 86.1 % removal) during the 60-minutes test period as disclosed in Table 2.

Table 2. Mercury Removal Performance of Granular Adsorbent Materials and CHROMOSORB P Pellets

^* Non detectable at an instrumental detection limit of 0.5 ppb

Example 6:

[096] A natural diatomite product was used as the feed material. Three aqueous solutions of a silane coating were prepared having a 1 % silane concentration, a 5% silane concentration, and a 10% silane concentration, respectively. The feed material was spray coated with the silane concentrations.

[097] The resulting heavy metal adsorbent powders were evaluated in a mercury removal test as illustrated in Table 3. 27 g of a granulated mercury adsorbent material prepared with various concentrations of silane in a solution was packed in 3.5-inch long plastic column with a 1 -inch diameter. The mercury removal test was a batch process of a 1 g/L sorbent loading for 30 minutes. The mercury concentration of the solution was measured at the end of 30 minutes using Cold Vapor Atomic Adsorption mercury analysis. The results are provided in Table 3, below. Figure 1 illustrates the mercury removal performance of powders prepared from various silane solutions.

Table 3: Mercur Removal Performance of Mercur Adsorbent Powders

First run; : Second run

Comparative Example 7:

[098] 100 ml of tetraethylorthosilicate was mixed with the same volume of methanol (100 ml_) in an Erlenmeyer flask covered with plastic wrap. After one hour of mixing at hotplate temperature of 70 ⁰ C, 64 ml_ of deionized water and 3 ml_ of 0.2N HCI were added to the solution. A 5% aqueous silane solution was added directly to the tetraethylorthosilicate solution. The mixed solution was stirred in an Erlenmeyer flask covered with plastic wrap for two hours to form sols. The sols were slowly added to a mixer with 124 g of natural diatomite powder, thereby forming granules.

[099] 25 g of a granulated mercury adsorbent granules prepared from powders was packed in 3.5-inch long plastic column with a 1 -inch diameter. An aqueous solution containing 8520 ppb ionic mercury prepared from an Atomic Absorption (AA) Standard Solution was pumped into the columns at a flow rate of 20 mL/min. The mercury concentration of the solution was measured at the end of 30 minutes using Cold Vapor Atomic Adsorption mercury analysis. The results are provided in Table 4, below. The exemplary granules composition was comparable to the control study, although the lack of chloroform in the exemplary granule composition may lower the production costs while retaining a comparable performance.

Table 4: Mercur Removal Performance of Mercur Adsorbent Granules

Example 8

[0100] A natural diatomite product was used as the feed material. Three aqueous solutions of a silane coating were prepared having a 5% silane concentration. The feed material was spray coated with the silane concentrations.

[0101] The resulting heavy metal adsorbent powders were evaluated in a mercury removal test as illustrated in Table 5, below. 25 g and 27 g of a granulated mercury adsorbent material were prepared with the 5% silane in a solution and was packed in a column with a flowrate of 20 mL/min for 30 minutes. The mercury concentration of the solution was measured at the end of 30 minutes using Cold Vapor Atomic Adsorption mercury analysis. The results, demonstrating in part the effect of pH of the granules on mercury removal, are provided in Table 5, below. Table 5: Mercur Removal Performance of Mercur Adsorbent Powders

Comparative Example 9 - MERSORB 1.5 and DUOLITE GT-73

[0102] 33 g of the inventive granular mercury adsorbent material sieved to a -20, +30 mesh was packed into a 1 -inch diameter, 6.5-inch long column. This sample was prepared without using a solvent. Instead, a sample of diatomaceous earth was spray coated with a 5% mercapto silane solution and agglomerated using TEOS to granulize the adsorbent material.

[0103] 33 g of MERSORB 1.5 activated carbon (Nucon International, Inc.; Columbus, Ohio, U.S.A.) was packed into a 1-inch diameter, 4.5 inch long column, and 33 g of DUOLITE GT-73 ion exchange resin (Rohm and Haas; Philadelphia, Pennsylvania, U.S.A.) was packed into a 1 -inch diameter, 3.5-inch long column for comparative studies. The volume difference among the three samples accounted for the different lengths of columns.

[0104] An aqueous solution containing from about 32 ppb to about 33 ppb mercury was passed through each column at a flowrate of 20 ml/min. The discharge solution was analyzed for its mercury concentration periodically at three hour intervals and shown in Table 6, below. The reporting limit of the mercury detection analyzer was 0.2 ppb, and the method detection limit was 0.036 ppb. Data points below 0.2 ppb were estimated values.

[0105] Mercury levels below about 1 ppb in the discharge stream indicate that the adsorbent material is sufficiently reducing the mercury concentration to acceptable levels. The inventive product maintained sufficient mercury adsorption of less than 1 ppb for up to 63 hours. After 63 hours, the mercury levels for the discharge stream treated by the inventive mercury adsorbent material exceeded 1 ppb. Accordingly, the effective

sorbent loading to reduce a mercury concentration from about 33 ppb to below 1 ppb was 0.44 g inventive granular mercury adsorbent material/L.

[0106] In contrast, the MERSORB 1.5 activated carbon failed to reduce mercury levels to an acceptable concentration after only three hours. The DUOLITE F-73 ion exchange resin failed after 11 hours. Table 6

Below detection limit; : Estimated value