Abstract: A method includes: (1) using a chelating agent, extracting divalent ions from a brine solution as complexes of the chelating agent and the divalent ions; (2) using a weak acid, regenerating the chelating agent and producing a divalent ion salt solution; and (3) introducing carbon dioxide to the divalent ion salt solution to induce precipitation of the divalent ions as a carbonate salt. Another method includes: (1) combining water with carbon dioxide to produce a carbon dioxide solution; (2) introducing an ion exchanger to the carbon dioxide solution to induce exchange of alkali metal cations included in the ion exchanger with protons included in the carbon dioxide solution and to produce a bicarbonate salt solution of the alkali metal cations; and (3) introducing a brine solution to the bicarbonate salt solution to induce precipitation of divalent ions from the brine solution as a carbonate salt.

Abstract: In an example of a method for reducing contamination, a purified imaging oil is formed by filtering an imaging oil through an imaging oil filter, and then filtering the imaging oil through a polar absorbent filter. A surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus is maintained by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

Abstract: A method of removing at least one cationic dye from an aqueous solution. The method includes contacting the aqueous solution with an adsorbent comprising a water-insoluble membrane disposed on a substrate. The water-insoluble membrane comprises cross-linked humic acid, at least one alginate, and hydroxyethyl cellulose. The contacting forms a treated aqueous solution having a lower concentration of the at least one cationic dye relative to the aqueous solution.

Abstract: A method of removing at least one cationic dye from an aqueous solution. The method includes contacting the aqueous solution with an adsorbent comprising a water-insoluble membrane disposed on a substrate. The water-insoluble membrane comprises cross-linked humic acid, at least one alginate, and hydroxyethyl cellulose. The contacting forms a treated aqueous solution having a lower concentration of the at least one cationic dye relative to the aqueous solution.

Abstract: A water recovery system can treat water in a confined space. The wastewater treatment system includes a cation-exchange device in which water to be treated, such as wastewater originating in a space station, water discharged by the human body, water produced by condensing water vapor contained in the air, is directly introduced to a cation-exchange resin and thereby treated by cation exchange; a diamond-electrode electrolysis device in which organic substances, urea, and other nitrogen compounds contained in water discharged from the cation-exchange device are decomposed; a catalytic decomposition device in which the residual organic component is brought into contact with a catalyst to be decomposed; an electrodialysis device in which water discharged from the catalytic decomposition device is treated by electrodialysis to produce desalted water as well as an acid and an alkali; and a mineral adding device in which a mineral is added to the desalted water.

Abstract: A method and system are provided in which a gold and/or silver-collecting resin-in-leach circuit comprises both co-current and counter-current sections.

Abstract: A method and apparatus for producing a purified liquid argon product in which liquid argon having oxygen impurities is produced in a cryogenic air separation plant by separating argon from oxygen within an argon column. An impure liquid argon stream, composed of part of the liquid argon, is purified in an adsorbent bed by adsorbing the oxygen impurities in an adsorbent to produce a purified liquid argon stream that constitutes the purified liquid argon product. During adsorption, the adsorbent bed is maintained at a reduced temperature with a coolant to prevent vaporization of the liquid argon. The bed is then regenerated by draining residual liquid argon from the adsorbent bed, introducing the residual liquid argon back into the air separation plant and then desorbing the oxygen impurities with a regeneration gas. After regeneration, the adsorbent bed is refilled with purified liquid argon prior to being brought back on-line.

Abstract: A method and apparatus for producing a purified liquid argon product in which liquid argon having oxygen impurities is produced in a cryogenic air separation plant by separating argon from oxygen within an argon column. An impure liquid argon stream, composed of part of the liquid argon, is purified in an adsorbent bed by adsorbing the oxygen impurities in an adsorbent to produce a purified liquid argon stream that constitutes the purified liquid argon product. During adsorption, the adsorbent bed is maintained at a reduced temperature with a coolant to prevent vaporization of the liquid argon. The bed is then regenerated by draining residual liquid argon from the adsorbent bed, introducing the residual liquid argon back into the air separation plant and then desorbing the oxygen impurities with a regeneration gas. After regeneration, the adsorbent bed is refilled with purified liquid argon prior to being brought back on-line.

Abstract: A simple and efficient method for producing 1,5-pentanediamine in a free form is provided. The method for producing 1,5-pentanediamine in a free form from a salt of 1,5-pentanediamine includes a step of adsorbing 1,5-pentanediamine in a free form onto a column of an ion exchange resin by applying a solution of salt of 1,5-pentanediamine to the column of the ion exchange resin, and a step of eluting a solution of the 1,5-pentanediamine in a free form from the ion exchange resin by applying an eluent solution to the column of the ion exchange resin onto which the 1,5-pentanediamine in a free form is absorbed.

Abstract: Systems and methods for removing organic contaminants from water may be used, for example, to treat produced water from a steam assisted heavy oil recovery operation. The treated produced water may be re-used to create steam. Alternatively, the produced water may be a blowdown stream treated to facilitate further treatment in a thermal crystallizer. The treatments may include pH adjustment or separating de-solubilized organics or both. Other treatments may include one or more of oxidation, sorption and biological treatments. The treatments may be used alone or in various combinations. One exemplary combination includes reducing the pH of produced water, separating de-solubilized organics from the produced water, and oxidizing the produced water or contacting the produced water with activated carbon.

Abstract: A composition comprising a substrate, an organic ion, and a metal binding agent, wherein the substrate comprises a natural clay, a synthetic clay, a natural zeolite, a synthetic zeolite, a polymer resin, lignite, kaolinite, serpentine, illite, chlorite, smectite, montmorillonite, saponite, sepiolite, nontronite, beidellite, hectorite, fuller's earth, attapulgite, bentonite, analcime, chabazite, heulandite, natrolite, phillipsite, stilbite, diethyl aminoethyl, quaternary aminoethyl, or combinations thereof, wherein the organic ion comprises quaternary amines, imidazolium salts, phosphonium salts, tetra alkyl ammonium, bis-(hydrogenated tallow)-dimethyl-ammonium chloride, bis-(hydrogenated tallow)-benzyl-methyl-ammonium chloride, 4,5-dihydro-1-methyl-2-nortallow-alkyl-1-(2-tallow-amidoethyl)-imidazolium methyl sulfate, 1-ethyl-4,5-dihydro-3-(2-hydroxyethyl)-2-(8-heptadecenyl)-imidazolium ethyl sulfate, or combinations thereof, and wherein the metal-binding agent comprises mercaptan, carboxylic acid, chelating a

Abstract: The present invention relates to a process for the treatment of liquid effluents laden with hydrocarbons, which comprises: feeding the effluents into a treatment tank; supplying the treatment tank with a reversible sorbent having a defined particle size; mixing the effluents with the reversible sorbent in the treatment tank in order to load said reversible sorbent with the hydrocarbons in the effluents; removing the hydrocarbon-laden reversible sorbent from the top of the treatment tank; extracting the treated effluents from the bottom of the treatment tank; and separating the hydrocarbons from the laden reversible sorbent from the treatment tank.

Abstract: Compositions containing vinyl polymers and ionophores selective for lead ions (e.g., polypyrrole copolymers), and methods for making these compositions are disclosed herein. The compositions can, for example, be used for detecting lead ions in a sample.

Abstract: Low metal biomass-derived pyrolysis oils and processes for producing the same are provided. Low metal biomass-derived pyrolysis oil is produced by a process of contacting metal-containing biomass-derived pyrolysis oil with an acidic ion-exchange resin having sulfonic acid groups. Low metal biomass-derived pyrolysis oil is removed from spent acidic ion-exchange resin after ion-exchange.

Abstract: One exemplary embodiment can be an apparatus for isomerizing a hydrocarbon stream rich in a C4 hydrocarbon and/or at least one of a C5 and C6 hydrocarbon. The apparatus can include: a first drier and a second drier adapted to receive a fluid including at least one reactant; and a reaction zone communicating with the first drier to receive the fluid including at least one reactant and with the second drier to receive the regenerant. Generally, the first drier operates at a first condition to dry the fluid including at least one reactant and the second drier operates at a second condition during regeneration with a regenerant. The regenerant can pass through a fluid tapering device for regulating the flow of the regenerant to the reaction zone.

Abstract: One exemplary embodiment can be an apparatus for isomerizing a hydrocarbon stream rich in a C4 hydrocarbon and/or at least one of a C5 and C6 hydrocarbon. The apparatus can include:a vessel containing a fluid including at least one reactant; a fluid transfer device receiving the fluid including at least one reactant from the vessel; at least one drier receiving the fluid including at least one reactant from the fluid transfer device; and a reactor communicating with the at least one drier to receive the fluid including at least one reactant. In addition, the at least one drier may communicate with the vessel at least by sending the fluid including at least one reactant or the regenerant through a fluid tapering device for at least one of regulating the flow and reducing the pressure of the regenerant to the vessel.

Abstract: Low metal, low water biomass-derived pyrolysis oils and methods for producing the same are provided. Metal- and water-containing biomass-derived pyrolysis oil is contacted with an acidic ion-exchange resin having sulfonic acid groups to produce a low metal, water-containing biomass-derived pyrolysis oil. The low metal, water-containing biomass-derived pyrolysis oil is removed from the spent ion-exchange resin after ion-exchange. The low metal, water-containing biomass-derived pyrolysis oil is distilled to produce a low metal, low water biomass-derived pyrolysis oil and a distillation product. The distillation product comprises one or both of an alcohol ion-exchange regenerant and an acidic ion-exchange regenerant which may be used to regenerate the spent ion-exchange resin. The regenerated acidic ion-exchange resin may be recycled. The spent alcohol and acid ion-exchange regenerants may be recovered and recycled.

Abstract: The present invention relates to the use of a carbonaceous adsorbent for the removal of a recalcitrant compound (1,4-dioxane) from contaminated water. The adsorbent is able to reduce the concentration of 1,4-dioxane from thousands of ?g/L to <3 ?g/L (the current EPA guideline). In addition, the adsorbent is regenerable in place with low pressure steam.

Abstract: This application discloses, in part, 1) a stationary phase column and compression designs for preparative chromatography, 2) a method of improving performance of silica gel chromatography by controlling the hydration of silica gel and acidifying the mobile phase, and 3) a method of extending the life of a silica gel column packing by cleaning or regenerating the silica gel stationary phase.

Abstract: Aniline copolymers and methods of making these copolymers are disclosed herein. The copolymers can, for example, be used for removing metal ions from a sample.

Abstract: A method for removing a metal from a metal-containing solution comprising contacting the metal-containing solution with a metal-removing composition comprising a substrate, an organic ion, and a metal binding agent, and recovering a solution having a lowered metal concentration when compared to the metal-containing solution.

Abstract: Aniline copolymers and methods of making these copolymers are disclosed herein. The copolymers can, for example, be used for removing metal ions from a sample.

Abstract: Novel water softening compositions and methods of treating hard water are provided. The compositions comprise a blend of sodium chloride and potassium chloride. The compositions are useful for regenerating ion exchange material in a water softening system and providing softened water containing both sodium and potassium ions.

Abstract: Novel water softening products and methods of treating hard water are provided. The products comprise a chloride-free, organic salt and a chelating agent. The products are useful for regenerating ion exchange material in a water softening system and providing softened water containing both sodium and potassium ions, while avoiding the formation of undesirable precipitates (e.g., low Ksp byproducts).

Abstract: One exemplary embodiment can be an apparatus for isomerizing a hydrocarbon stream rich in a C4 hydrocarbon and/or at least one of a C5 and C6 hydrocarbon. The apparatus can include: a first drier and a second drier adapted to receive a fluid including at least one reactant; and a reaction zone communicating with the first drier to receive the fluid including at least one reactant and with the second drier to receive the regenerant. Generally, the first drier operates at a first condition to dry the fluid including at least one reactant and the second drier operates at a second condition during regeneration with a regenerant. The regenerant is displaced from the drier using a down-flow regenerant displacement assembly.

Abstract: The present invention relates to functionalized polymeric sorbents and processes of employing them to remove low level contaminants from fluid streams. Poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate) functionalized with a compound having the structure NH2—R1OH wherein R1 is a substituted or unsubstituted phenylene may be particularly useful to remove low levels of phenol compounds from, for example, an aqueous fluid stream comprising one or more sugars such as results from a hydrolysis of lignocellulosic materials.

Abstract: An apparatus for conducting single-pass filtration of ink waste is disclosed. The apparatus includes: a filter connected to a housing unit and a plurality of absorbent layers within the housing unit, wherein the plurality of absorbent layers are in any order and include: a layer for removing metal and polar compounds, a layer for removing non-polar color impurities, a layer for removing acid functional components, a layer for removing additives with polar or protic functional groups, and a layer for removing residual water. A process and a system that include or utilize the apparatus are also disclosed.

Abstract: The present invention relates to functionalized polymeric sorbents and processes of employing them to remove low level contaminants from fluid streams. Poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate) functionalized with a compound having the structure NH2—R1OH wherein R1 is a substituted or unsubstituted phenylene may be particularly useful to remove low levels of phenol compounds from, for example, an aqueous fluid stream comprising one or more sugars such as results from a hydrolysis of lignocellulosic materials.

Abstract: The invention provides an enrichment process for a PGM-group metals containing stream, said process including the steps of contacting activated carbon particles with a PGM-rich stream by contacting the stream with a batch of the particles on a continuous basis, whereby at least some of the PGM-group metals are adsorbed from the stream onto active surface sites of the activated carbon and a PGM-metals depleted stream passes out of contact with the activated carbon batch, thereafter stripping the PGM-group metals from the activated carbon batch by means of a concentrated HCl solution as stripping agent, wherein the stripping agent is contacted with the activated carbon batch on a continuous flow basis and the PGM-group metals loaded stripping agent is removed from contact with the activated carbon from which the PGM-group metals have been stripped, and then regenerating the activated carbon batch by washing with water and, if necessary, reactivating the carbon particles.

Abstract: A process for obtaining one or more than one salt of an organic acid(s), or organic acid(s), from an aqueous sugar stream comprising one or more than one mineral acid and the organic acid(s) is provided. The process comprises introducing the aqueous sugar stream to a separation system comprising one or more beds of anion exchange resin and obtaining a stream therefrom comprising the sugar. The one or more beds of anion exchange resin are then regenerated in one or more stages to produce at least one product stream comprising the organic acid, a salt of the organic acid, or a combination thereof, and a separate outlet stream comprising the mineral acid, a salt of the mineral acid, or a combination thereof. The product stream is then recovered. The separation may be conducted with two separation units, or using a single anion exchange unit.

Abstract: The present invention provides a functional powder capable of effectively adsorbing impurities in water treatment. The powder can be rapidly separated by use of magnetic force, and hence is excellent in workability. This functional powder comprises magnetic particles having surfaces modified with hydrophobic groups and hydrophilic groups loaded thereon. The hydrophobic groups have a function of adsorbing the impurities, and the hydrophilic groups have a function of dispersing the powder stably in water. The numbers M and N of the hydrophobic groups and the hydrophilic groups, respectively, satisfy the condition of 0.2<M/N<0.8, so that the adsorbability to impurities and the dispersion stability are both ensured.

Abstract: Perchlorate is removed and effectively destroyed in devices and methods that employ a eluting solvent in which the anion of an acid solubilizes Ti (III), which may be electrochemically generated or added in situ. Using such solvents, destruction of perchlorate is unexpectedly and several orders of magnitude faster than using solvents without solubilizing acids. In most preferred aspects, the solubilizing acid is methane sulfonic acid and/or sulfamic acid, and Ti (III) is electrochemically generated. Perchlorate destruction will then result in formation of Ti (IV), which may be present in the eluent in a subsequent elution.

Abstract: Systems and methods for removing perchlorate load off of ion exchange resins are disclosed. The systems and methods rely upon direct contact between the resin and a liquid product formed by the culturing of perchlorate-destroying microorganisms. These methods can be incorporated into methods for removing perchlorate from aqueous streams. A resin product comprising an anion exchange resin with a coating of perchlorate-destroying microorganisms on its surface is also disclosed.

Abstract: A method for removing ionic, organic and elemental mercury from aqueous streams such as wastewater streams from hydrocarbon processing. The method comprises four primary removal steps. First, a mercury precipitant is added to the stream to convert dissolved ionic species of mercury water-insoluble form. The majority of these precipitated solids, as well as other forms of particulate mercury, are subsequently removed by means of gas flotation. Following the flotation step, additional particulate and precipitated ionic mercury removal is accomplished with media filtration and finally, activated carbon acts to remove the remaining dissolved ionic mercury species as well as elemental and organic forms of mercury.

Abstract: A method of desorbing a volatile component from a spent adsorbent is disclosed, which includes flowing a stream of supercritical carbon dioxide through a rotating packed bed of the spent adsorbent; and collecting an effluent from the rotating packed bed, which contains supercritical carbon dioxide and the volatile component entrained therein. In one embodiment of the present invention a spent activated carbon from a process for recovering 2,2,3,3-tetrafluro-1-propanol from a gas stream containing 2,2,3,3-tetrafluro-1-propanol is regenerated by flowing a stream of supercritical carbon dioxide through a rotating packed bed of the spent activated carbon.

Abstract: There disclosed a water reuse method in which a surfactant is easily removed from surfactant-including for-treatment water in a cleaning device, whereby water can be reused, and an adsorbent can easily be regenerated only by exposing the adsorbent to an electrolytic solution, and a washing machine including the function. The method includes a surfactant adsorption treatment step of performing a treatment to adsorb and remove a surfactant in surfactant-including for-treatment water such as cleaning water and rinse water used in a washing machine W by hydrotalcite as an anion exchanger or zeolite as a cation exchanger, and a water reuse step of using, in the washing machine W, the for-treatment water treated in the surfactant adsorption treatment step.

Abstract: Systems and methods for removing perchlorate load off of ion exchange resins are disclosed. The systems and methods rely upon direct contact between the resin and a liquid product formed by the culturing of perchlorate-destroying microorganisms. These methods can be incorporated into methods for removing perchlorate from aqueous streams. A resin product comprising an anion exchange resin with a coating of perchlorate-destroying microorganisms on its surface is also disclosed.

Abstract: Apparatus, materials, and methods for removing ammonia from fluid using metal hydroxides (e.g. zinc hydroxide) and metal cation loaded media (e.g. zinc loaded ion exchange resins); the metal hydroxides and metal cation loaded media may be regenerated with a weak acid (pKa between 3 and 7). Alternatively, ammonia is removed from fluids by using H2SO4 and ZnSO4 and metal cation loaded media; the metal cation loaded media may be regenerated with H2SO4 and ZnSO4; the ammonia containing H2SO4 and H2SO4 may be concentrated as necessary to form (NH4)2SO4.ZnSO4.6H2O (ammonium zinc sulfate hexahydrate) crystals. These crystals are removed from the mother liquor and heated to temperatures exceeding 200° C. releasing NH3 and H2O vapor upon the decomposition of the crystals.

Abstract: Alkali metal ions are separated off from alkoxylates containing alkali metal ions by a process comprising: a) dilution of the alkali metal-containing alkoxylate with an inert solvent, b) treatment of the alkali metal-containing solution of the alkoxylate with a cationic exchanger in order to obtain a substantially alkali metal-free solution of the alkoxylate, and c) removal of the solvent from the substantially alkali metal-free solution of the alkoxylate in order to obtain a substantially alkali metal-free and substantially solvent-free alkoxylate.

Abstract: This invention pertains to adsorption by an adsorbent of an adsorbate and to regeneration of the loaded adsorbent. The adsorption includes contacting an adsorbent selected from arylene-bridged polysilsesquioxanes and derivatives thereof with an adsorbate selected from aromatics and heterocyclics, particularly monocyclic heterocyclics containing carbon and nitrogen atoms in a 6-member non-aromatic ring, for a period of time sufficient to adsorb all or part of the adsorbate by the adsorbent. Regeneration of the loaded adsorbent includes removing all or part of adsorbate from the adsorbent by means of an alcohol wash or by thermal desorption of the adsorbent containing adsorbate.

Abstract: A simulated moving bed separation system is provided, in which a fluid circulation flow path can be washed for a short time. This system is provided with a circulation flow path having two or more packed beds connected in series and endlessly to each other, with desorbing-charging inlet, extract draw-out port, feedstock introducing port and raffinate draw-out port arranged in this order in the direction of flow of a circulation liquid, which are allowed to intermittently shift in the direction while being kept in this order, and with packed bed-washing pipes, valves and pumps. A desorbing liquid is introduced through the desorbing liquid introducing port into the circulation flow path. An extract rich in a strongly adsorptive constituent to be separated is drawn out through the extract draw-out port.

Abstract: The resist stripping waste liquid regenerating apparatus of the invention regenerates a resist stripping waste liquid to obtain a resist stripping regenerated liquid. The apparatus is provided with a membrane separating apparatus which employs a membrane with a molecular weight cutoff of 100-1500 to separate a resist stripping waste liquid into a concentrated liquid and a permeating liquid, an adjusting tank which stores the permeating liquid and adjusts the concentration of an alkanolamine and organic solvent, means for supplying the alkanolamine to the adjusting tank, and means for supplying the organic solvent to the adjusting tank. This construction adequately reduces the resist concentration of the permeating liquid since the resist in the resist stripping waste liquid cannot permeate the membrane. It is thereby possible to lessen the need for dilution of the resist concentration and thus satisfactorily reduce the amount of alkanolamine and organic solvent supplied to the adjusting tank.

Abstract: A method for desalination of water or of aqueous solutions derived from industrial process that use two columns: the first treatment column containing a mixed bed of ion exchange resins, in which the cation exchange resins are regenerated, and a second column, into which the anion exchange resins are transferred and regenerated, to be then reintroduced from the bottom into the above mentioned first column, where they rise through the cation exchange resins.

Abstract: A process for modifying a medium is disclosed that includes treating a medium having a metal ion sorption capacity with a solution that includes: A) an agent capable of forming a complex with metal ions; and B) ions selected from the group consisting of sodium ions, potassium ions, magnesium ions, and combinations thereof, to create a medium having an increased capacity to sorb metal ions relative to the untreated medium.

Abstract: An improved method for regenerating ion exchange resin in a treatment tank having a flow direction, which includes the steps of providing a supply of regenerant under pressure into the tank, and introducing the regenerant into the tank in an opposite flow direction to the treatment flow direction. In the preferred embodiment, the regenerant is a combination of CO2 which is mixed with water to form carbonic acid and citric acid. This mixture is then introduced into the treatment tank without storage.

Abstract: Non-chloride containing regenerant compositions of potassium acetate or potassium formate, at least one surfactant and at least one chelating agent as well as methods for efficient regeneration of water softeners utilizing the regenerant compositions are disclosed. A preferred regenerant composition is a solution of potassium acetate or potassium formate with citric acid and octyl phenol ethoxylate.

Abstract: A process is disclosed for the recovery of gold and/or silver values from activated carbon, wherein they are adsorbed as cyanide complexes. The process uses an eluant containing sugar. The process allows the eluant to pass through fresh carbon twice, thereby reducing the volume of the gold-loaded eluant. This, in turn, reduces the size of the electrowinning or zinc precipitation circuits. The process also improves elution efficiency when barren electrowinning solution is recycled in the elution process.

Abstract: Equipment and procedures for regenerating ion exchange resin mixed beds, used for the desalination of water or of aqueous solutions from industrial processes (process solutions), that use two columns: the first treatment column (C1), containing a mixed bed of ion exchange resins, in which the cation exchange resins are regenerated, and a second column (C2) into which the anion exchange resins are transferred and regenerated, to be then reintroduced from the bottom into the above mentioned first column (C1), where they rise through the cation exchange resins and intimately mix with the anionic exchange resins.

Abstract: An adsorbent that exhibits a high specificity in adsorbing immunoglobulins and/or complexes thereof, is extremely reduced in the lowering of the adsorption characteristic during sterilization or storage, is highly stable and safe, and is prepared by immobilizing on a water-insoluble support either a peptide derivative which has undergone at least one of the deletion, substitution, insertion, or addition of amino acids in a peptide having a specified amino acid sequence or an amino acid sequence, or the above peptide derivative which has undergone the addition of Lyn or Cys at the amino and/or carboxyl terminal thereof; a device for adsorption and removal made by packing the adsorbent in a vessel equipped with effluent preventing means; and a method of adsorbing and removing immunoglobulins and/or complexes thereof contained in the blood, plasma or other body fluids with the adsorbent.

Abstract: A process for separating one chiral compound from a mixture of chiral compounds is disclosed. The separation process involves using a chiral stationary phase (CSP) which comprises a chiral organic material deposited on an amorphous silica support having a unimodal distribution of pore sizes in the range of about 300 .ANG. to about 25,000 .ANG. and a surface area of less than about 30 m.sup.2 /g.