Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
  • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00177—Controlling or regulating processes controlling the pH

Definitions

• This invention relates generally to enhanced adsorbent particles, particularly particles that have been adsorbent enhanced by contacting with acid.
• Oxides of metals and certain non-metals are known to be useful for removing constituents from a gas or liquid stream by adsorbent mechanisms.
• the use of activated alumina is considered to be an economical method for treating water for the removal of a variety of pollutants, gasses, and some liquids. Its highly porous structure allows for preferential adsorptive capacity for moisture and contaminants contained in gasses and some liquids. It is useful as a desiccant for gasses and vapors in the petroleum industry, and has also been used as a catalyst or catalyst-carrier in chromatography and in water purification. Removal of contaminants such as phosphates by activated alumina are known in the art. See, for example, Yee, W., "Selective Removal of Mixed Phosphates by Activated Alumina," J.Amer. Walerworks Assoc, Vol. 58, pp.239-247 (1966).
• U.S. Patent No. 4,795,735 to Liu et al. discloses an activated carbon alumina composite and a process for producing the composite.
• the composite is prepared by blending powders of each of the activated carbon and activated alumina constituents. After the blend is thoroughly mixed, an aqueous solution is added to permit the activated alumina to rehydratably bond to the carbon particles. The amount of water added does not exceed that which prevents the mix from being extruded or agglomerated. After the water is added, the mix is subjected to a shaping or a forming process using extrusion, agglomeration, or pelletization to form a green body. The green body is then heated to a temperature of 25- 100 ⁇ C or higher.
• the composite may be strengthened by peptizing by adding nitric acid to the mixture. It is disclosed that the alumina can serve as the binder as well as the absorbent.
• This patent does not use a calcined alumina.
• Liu et al. discloses an amorphous alumina trihydrate powder, such as CP2 obtained from Alcoa and an amorphous alumina trihydrate powder such as CP-1 or CP-7, which are recited in U.S. Patent No. 4,579,839, incorporated by reference in Liu et al.
• Liu et al. 's use of the term active refers to the surface water being dried and does not refer to a calcined particle.
• Liu et al. uses acid to strengthen the particle and not to enhance its adsorbent properties.
• Liu et al. uses an alumina precursor, which is an absorbent and not an adsorbent.
• Example 2 discloses an alumina hydrate formed by partially dehydrating alpha-alumina trihydrate in a rotary dryer by counter-current flow with a heated gas and an inlet temperature of about 1200°F and an outlet temperature of about 300°F. The resulting product was washed with 5% sulfuric acid, rinsed with water and dried to about 2% free water content. Solid sucrose was mixed with the hydrate and the mixture heated.
• Example 4 discloses that the procedure of Example 2 was repeated except that calcined alumina was used. The product was unsuitable when calcined alumina was used. Thus, the acid washed product of Example 2 was not a calcined alumina.
• U.S. Patent No. 4,051 ,072 to Bedford et al. discloses a ceramic alumina that can be treated with very dilute acid to neutralize the free alkaline metal, principally Na 2 O, to enable impregnation with catalytic material to a controlled depth of from at least 90 to about 250 microns.
• This patent does not use a crystallized aluminum oxide that has been calcined in accordance with the instant invention.
• This patent calcines the particle at a temperature of from about 1700°F to about 1860°F (927 ⁇ C to 1016 ⁇ C) to form a ceramic material, specifically what is referred to herein as an alpha alumina.
• activated carbon materials which have been subjected to carbonization and activation treatments, and then further subjected to an acid treatment and a heat treatment, have a high catalytic activity and are suitable as catalysts for the decomposition of hydrogen peroxide, hydrazines or other water pollutants such as organic acids, quaternary ammonium-salts, and sulfur-containing compounds. Acid is used to remove impurities and not to enhance the adsorbent features.
• This patent also does not utilize a particle of the instant invention.
• Adsorbent particles of the prior art have not achieved the ability to remove particular contaminants from a liquid or gas stream, such as. for example, a waste stream or drinking water, to acceptably low levels. Additionally, the adsorbent particles of the prior .art have not been able to bind tightly to particul.ar contaminants so that the adsorbent particle/contaminant composition can be safely disposed of in a landfill. Thus, there has been a need in the art for adsorbents that have improved ability to adsorb particular materials, particularly contaminants from a gas or liquid stream, to thereby purify the stream. There has been a need in the art for the adsorbent particles to tightly bind to the adsorbed contaminant.
• this invention in one aspect, relates to a process for producing an enhanced adsorbent particle comprising contacting a non-amorphous, non-ceramic, crystalline, porous, calcined, aluminum oxide particle that was produced by calcining at a particle temperature of from 400° C to 700° C, with an acid for a sufficient time to increase the adsorbent properties of the particle.
• the invention further provides a process for producing an enhanced adsorbent particle comprising contacting a non-amorphous, non-ceramic, crystalline, porous, oxide adsorbent particle with an acid for a sufficient time to increase the adsorbent properties of the particle.
• the invention provides for particles made by the process of the instant invention.
• the invention provides for a process for reducing or eliminating the amount of contaminants in a stream comprising contacting the particle of the invention with the stream for a sufficient time to reduce or eliminate the contamination from the stream.
• the invention provides a composition comprising the particles of the invention.
• particle as used herein is used interchangeably throughout to mean a particle in the singular sense or a combination of smaller particles that are grouped together into a larger particle, such as an agglomeration of particles.
• ppm refers to parts per million and the term “ppb” refers to parts per billion.
• this invention in one aspect, relates to a process for producing an enhanced adsorbent particle comprising contacting a non-amorphous, non-ceramic, crystalline, porous, calcined, aluminum oxide particle that was produced by calcining at a particle temperature of from 400° C to 700° C, with an acid for a sufficient time to increase the adsorbent properties of the particle.
• This process can also consist essentially of or consist of the particular process steps as described above or further including the additional features described below.
• the invention further provides a process for producing an enhanced adsorbent particle comprising contacting a non-amorphous, non-ceramic, crystalline, porous, oxide adsorbent particle with an acid for a sufficient time to increase the adsorbent properties of the particle.
• This process can also consist essentially of or consist of the particular process steps as described above or further including the additional features described below.
• the invention provides for p-articles made by the process of the instant invention.
• the invention provides for a process for reducing or eliminating the amount of contaminants in a stream comprising contacting the particle of the invention with the stream for a sufficient time to reduce or eliminate the contamination from the stream.
• the invention provides a composition comprising the particles of the invention.
• the particles of this invention have improved or enhanced adsorptive features.
• the particles of this invention can adsorb a larger amount of adsorbate per unit volume or weight of adsorbent particles than a non-enhanced particle.
• the particles of this invention can reduce the concentration of contaminants or adsorbate material in a stream to a lower absolute value than is possible with a non-enhanced particle.
• the particles of this invention can reduce the contaminant concentration in a stream to below detectable levels, never before achievable with prior art particles.
• Enhanced adsorptive features is intended to include both ion capture and ion exchange mechanisms. Ion capture refers to the ability of the particle to bond to other atoms due to the ionic nature of the particle.
• Ion exchange is well known in the art and refers to ions being interchanged from one substance to another.
• Adsorption is a term well known in the art and should be distinguished from absorption.
• the adsorbent particles of this invention chemically bond to and very tightly retain the adsorbate material.
• the acid contacting of the particle enhances the adsorptive capacity of the particle by adding onto the surface of the particle pores ion moieties present in the acid or present in particle surface water, such as OHM PT* " , and/or the anion of the acid.
• the particle covalently or ionically bonds to these ions. It is believed that the particle exhibits an excess and thus an increased charge in comparison to non-enhanced particles.
• any adsorbent particle that is non- amorphous, non-ceramic, crystalline, porous, has oxygen in the crystal lattice, and can hold a charge can be used.
• the particles of this invention are in the crystalline form and are therefore non-amorphous.
• Adsorbent particles that are very rigid or hard, are not dissolved to any detrimental degree by the acid, and which have initially high, pre- enhanced adsorptive properties are preferred. Examples of such particles include, but are not limited to, metal oxides, such as transition metal oxides and Group IIIA and Group IVA metal oxides, and oxides of non-metals such as silicon and germanium.
• Preferred adsorbents include oxides of aluminum, silicon, manganese, copper, vanadium, zirconium, iron, and titanium. Even more preferred adsorbents include aluminum oxide (Al 2 O 3 ), silicon dioxide (SiO 2 ), manganese oxides (MnO, MnO 2 , Mn 2 O 3 , and Mn 3 O 4 ), copper oxides (CuO and Cu 2 O), vanadium pentoxide (V 2 O 5 ), zirconium oxide (ZrO 2 ), iron oxides (FeO, Fe 2 O 3 , and Fe 3 O 4 ), and titanium dioxide (TiO 2 ).
• the oxide is aluminum oxide (Al 2 O 3 ) that has been produced by calcining at a particle temperature of from 400 ⁇ C to 700 "C.
• Al 2 O 3 aluminum oxide
• These preferred aluminum oxide particles are preferably in the gamma, chi-rho, or eta forms.
• the ceramic form of Al 2 O 3 such as the alpha form, are not included as a part of this invention.
• the Al 2 O 3 particles of this invention have a pore size of from 3.5 nm to 35 n (35A to 350 A) diameter and a BET surface area of from 120 to 350 m 2 /g.
• the particle is aluminum oxide that has been pre-treated by a full calcination process.
• Calcined aluminum oxide particles are well known in the art. They are particles that have been heated to a particular temperature to form a particular crystalline structure. Processes for making calcined aluminum oxide particles are well known in the art as disclosed in, e.g., Physical and Chemical Aspects of Adsorbents and Catalysts, ed. Linsen et al., Academic Press (1970), which is incorporated by reference herein.
• the Bayer process can be used to make aluminum oxide precursors.
• pre-calcined aluminum oxide that is, the aluminum oxide precursor (Al(OH) 3 ), and calcined aluminum oxide are readily commercially available.
• Calcined aluminum oxide can be used in this dried, activated form or can be used in a partially or near fully deactivated form by allowing water to be adsorbed onto the surface of the particle. However, it is preferable to minimize the deactivation to maximize the adsorbent capability.
• "activated" refers only to the surface water being removed from the particle to increase its adsorbent ability.
• activated refers to a particle that has first been calcined and is then also maintained in its dried state.
• all active particles of the invention have also been calcined.
• the particles are not limited to any physical form and can be in the particulate, powder, granular, pellet, or the like form.
• the particles are preferably in a gel state.
• the acid that can be used in this invention can be any acid or mixture of acids that can add extra ion moieties onto the surface of the pores of the oxide particle.
• Typical ion moieties include OHM H " M and the anion of the acid.
• acids include, but are not limited to. nitric acid, sulfuric acid, hydrochloric acid, boric acid, acetic acid, formic acid, phosphoric acid, and mixtures thereof.
• the acid is acetic acid because it is relatively safer to handle than most other acids and because of its cost effectiveness.
• the acid is diluted with water to prevent dissolution of the particle and for cost effectiveness.
• a dilute solution of the acid is required to achieve maximum or saturated loading of the ion moieties on the particle.
• a 0.5 wt. % and even a 0.1 % acetic acid solution has been found effective.
• concentrations of acid can be used in this invention from very dilute to very concentrated depending on the hazards involved and the economics of production.
• the acid is too concentrated, it will etch the particle causing an increase in macropores while eliminating micropores, which is detrimental to the particles of this invention.
• the acid treatment is preferably of a concentration and length of time to be more than a mere surface wash but less than an etching.
• the acid preferably has some water present to provide OH " and or H * ion moieties, which bond with the particle.
• the water is preferably distilled water to minimize the amount of impurities contacting the particle.
• the particle of the invention is made by the following process.
• the particle is contacted with an acid.
• the particle can be contacted with the acid by various means including by the particle being dipped in, extensively washing with, or submerged in the acid.
• the length of time the particle must be contacted with the acid varies according to the ability of the particular particle to be saturated with the ion moieties.
• the time can be as low as a few minutes, at least 15 minutes, at least one hour, at least 6 hours, at least 12 hours, or at least one day, to assure saturation.
• the time must be sufficient to at least increase the adsorbent properties of the particle by adding ion moieties to the particle.
• the particle is submerged in the acid, and saturation is typically complete when the particle stops bubbling.
• the contacting should be substantial enough to provide penetration of the acid throughout the pores of the particle. Mere washing the outside surface of the particle to remove impurities is not sufficient to provide adequate penetration of the acid into and throughout the pores of the particle.
• the acid contacted particle is then optionally rinsed. Rinsing insures that the particle does not later release acid concentrated dust that may become airborne and which can be inhaled. Rinsing of the acid contacted particle does not reduce the enhanced adsorptive capability of the particle.
• the particle is preferably rinsed with distilled water to minimize impurity contact.
• the particle is dried by a low to moderate heat treatment to remove excess liquid, such as acid or water, from the rinsing step to thereby increase the activity of adsorption. Drying of the particle also reduces the transfer cost of particle.
• the particle is not calcined or recalcined after acid treatment. Such recalcining would detrimentally change the surface characteristics by closing up the micropores.
• the size of the particles used in this invention can vary greatly depending on the end use. Typically, for adsorption or catalytic applications, a small particle size such as 20 ⁇ m or greater are preferable because they provide a larger surface area than large particles.
• the particle of this invention can be used in any adsorption or ion capture application known to those of ordinary skill in the art.
• the particle is used for environmental remediation applications.
• the particle can be used to remove contaminants, such as heavy metals, organics, including hydrocarbons, inorganics, or mixtures thereof.
• contaminants include, but are not limited to, acetone, microbials such as cryptosporidium, ammonia, benzene, chlorine, dioxane, ethanol, ethylene. formaldehyde, hydrocarbon cyanide, hydrogen sulfide. methanol, methyl ethyl ketone. methylene chloride, propylene, styrene.
• the particle of this invention can remediate individual contaminants or multiple contaminants from a single source. In essence, anywhere ions are used to capture pollutants, this invention achieves improved efficiency by adsorbing a higher amount of contaminants and by reducing the contamination level to a much lower value than by non-enhanced particles.
• particles of the invention are typically placed in a container, such as a filtration unit.
• the contaminated stream enters the container at one end, contacts the particles within the container, and the purified stream exits through another end of the container.
• the particles contact the contaminants within the stream and bond to and remove the contamination from the stream.
• the particles become saturated with contaminants over a period of time, and the particles must be removed from the container and replaced with fresh particles.
• the contaminant stream can be a gas stream or liquid stream, such as an aqueous stream.
• the particles can be used to remediate, for example, waste water, production facility effluent, smoke stack gas, auto exhaust, drinking water, and the like.
• the particle of the invention can be used alone, in combination with other particles prepared by the process of the invention, and/or in combination with other adsorbent particles known in the art.
• the particles can be combined in a physical mixture or agglomerated using techniques known in the art. such as with a binder, to form a multifunctional composite particle.
• the invention is directed to a composition comprising an aluminum oxide particle made by the acid enhancing process of the invention.
• this composition further comprises a co-adsorbent particle.
• This co-particle is preferably any adsorbent particle known in the art.
• Such co-adsorbent particles can be preferably non-amorphous, non-ceramic, crystalline, porous, oxide adsorbent particles, more preferably silicon dioxide, or a metal oxide, such as manganese oxides (MnO, MnO 2 , Mn 2 O 3 , and Mn 3 O 4 ), copper oxides (CuO and Cu 2 O), vanadium pentoxide (V 2 O 5 ), zirconium oxide (ZrO 2 ), iron oxides (FeO, Fe 2 O 3 , and Fe 3 O 4 ), and titanium dioxide (TiO 2 ).
• the co-particle can acid-enhanced or non-acid enhanced. In a preferred embodiment, the co-particles are not acid-enhanced.
• the composition comprises aluminum oxide made by the acid enhanced process of the invention, copper oxide, and manganese oxide.
• these components are in a proportion of from 50-98 parts, more preferably 80-95 parts, even more preferably 88 parts acid enhanced aluminum oxide; and 1-49 parts, more preferably 4- 19 parts, even more preferably 6 parts of each of copper oxide and manganese oxide.
• the composition is held together using a colloidal alumina binder that has been crosslinked as described below.
• this composition can be used to remediate organics. such as hydrocarbons, even more preferably, trichloroethylene (TCE).
• TCE trichloroethylene
• the acid-enhanced aluminum oxide/co-particle embodiment of the invention to remediate organic contaminants is due to a catalytic degradation of the organic contaminant, even at room temperature.
• This catalytic activity is possibly present because the inventive co-particle was challenged with a high concentration of organic contaminants and no organic contaminants were found on the surface of the particle by visual observation or on the residual solution after TCLP analysis.
• the Al 2 O 3 in combination with one or more oxides of manganese, copper, and/or iron are particularly suited to possibly catalytically degrade organics, such as hydrocarbons and trichloroethylene.
• Binders for binding the individual particles, either of the same or different types, to form an agglomerated particle are known in the art or are described herein. Binders that do not interfere with the adsorbent features are preferred. In a preferred embodiment, the binder can also act as an adsorbent.
• a preferred binder for the agglomerated particle is colloidal alumina or colloidal silica. At approximately 450 °C, the colloidal alumina goes through a transformation stage and cross-links with itself. Colloidal silica cross-links with itself if it is sufficiently dried to remove water.
• the total adsorbent particle mixture is colloidal alumina or colloidal silica to provide the necessary crosslinking during heating to bind the agglomerated particle into a water-resistant particle.
• the particle can then withstand exposure to all types of water for an extended time and not degrade.
• the agglomerated particle is made by mixing colloidal alumina with the adsorbent particles of the invention.
• the acid enhanced particles have been produced and are ready for agglomeration prior to mixing with the acid below.
• from about 5% to about 99%, more preferably 20%, by weight of the mixture is colloidal alumina.
• the particle mixture is then mixed with .an acid solution such as, for example, nitric, sulfuric, hydrochloric, boric, acetic, formic, phosphoric, and mixtures thereof.
• the acid is 5% nitric acid solution.
• the colloidal alumina, adsorbent particles, and acid solution are thoroughly mixed so as to create a homogenous blend of all elements.
• the mixture is then extruded and chopped up into the desired size.
• the resultant particles are heated to at least 450 °C to cause the colloidal alumina crosslinking to occur.
• the particle of this invention bonds with the contaminant so that the particle and contaminant are tightly bound. This bonding makes it difficult to remove the contaminant from the particle, allowing the waste product to either be disposed of into any public landfill or used as a raw material in the building block manufacturing industry.
• Measurements of contaminants adsorbed on the particles of this invention using an EPA Toxicity Characteristic Leachability Procedure (TCLP) test known to those of skill in the art showed that there was a bond at least as strong as a covalent bond between the particles of this invention and the contaminants.
• TCLP Toxicity Characteristic Leachability Procedure
• Enhanced aluminum oxide particles were made by the process of this invention.
• Gamma aluminum oxide particles were produced by calcining Al(OH) 3 at a particle temperature of 550-560°C. 20 liters of this aluminum oxide were submerged in a tank containing 0.5% by weight acetic acid in distilled water. The total volume of solution was 15.56 liters. The alumina was allowed to sit for approximately 15 minutes to allow saturation of the solution. The acid solution was drained off and the remaining alumina was rinsed in a tank of 30 liters of distilled water. The distilled water was drained and the remaining alumina was dried at a temperature of 121 °C for 90 minutes.
• Enhanced gamma aluminum oxide particles of the present invention were made according to the procedures of Example 1.
• Two identical five gallon containers were filled with the alumina oxide for lead removal.
• One container was filled with 16 liters of the treated alumina of this invention.
• the other was filled with 16 liters of untreated alumina.
• Two tanks were prepared each containing 100 gallons of lead acetate tri-hydrate spiked distilled water. The tanks were mixed thoroughly for 30 minutes. After 30 minutes of mixing, the concentrations of the lead in the water were determined.
• the lead containing water from each tank was passed through the containers of alumina.
• Example 1 A comparison was made between treated alumina of this invention and non- treated alumina for removing phosphate.
• Chi-rho aluminum oxide particles were produced by calcining Al(OH) 3 at a particle temperature of 480-520°C.
• Enhanced chi- rho aluminum oxide particles of the present invention were then made according to the procedures of Example 1. The performance of the particles was measured using the same procedures of Example 1, except that one chromatographic column was filled with 20 cc of the treated alumina and the other column was filled with 20 cc of the untreated alumina and the test solution was 9.3 mg 1 of KH 2 PO 4 .
• the results of the tests are set forth in Table 3 below.
• a combination particle of this invention was made and tested for its ability to remove trichloroethylene.
• 70 g of acid enhanced gamma aluminum oxide particles made by the procedure of Example 1 were mixed with 20 g of alumina type gel, 5 g of Mn 2 O , and 5 g of CuO until the mixture was homogeneous.
• the particle mixture was then mixed with 5% nitric acid solution until the mixture reached a suitable consistency for agglomeration.
• the mixture was extruded and cut into a particle size of about 1,000 ⁇ m and heated to 500 "C for 15 minutes to crosslink the colloidal alumina.
• the 1 ppm VOA stock solution was obtained by dilution (deionized water) of a 1000 ⁇ g ml VOA mix (Supelco) which contained the following analytes in methanol; (1) benzene, (2) chlorobenzene, (3) toluene, (4) trichloroethylene, and (5) 1,1-dichloroethylene.
• the other stock solution (1 ppm TCE in water) was obtained by dissolving 0.01 g spectrophotometric grade TCE (Aldrich) in deionized water followed by dilution to a liter.
• the fifth bed volume from each column was collected (no headspace) in 2 ml screw-cap vials with Teflon-coated silicone septa and stored on ice prior to GC/MS analysis (EPA Method 8260). The results are as follows.
• TCE adsorption and TCLP extraction procedures were performed as follows.
• a 20.0114-gram (about 24.50 bed volume) sample of the Al 2 O 3 /CuO/Mn 2 O 3 combination particle of Example 5 (designated as 0307595TCE1 ) was wet packed into a 50-mL buret (with removable stopcock) plugged with glass wool. The sample was charged with five bed volumes of water. The sorbent material was then quantitatively transferred into the Zero Headspace Extractor (ZHE) apparatus into which 200 mL of water was added, appropriately sealed and agitated for 18 hours. The filtered solution was collected in two 100 mL vials, stored in the refrigerator at 4 ⁇ C until analysis by GC/MS.
• the Finnigan MAT Magnum ion trap GC/MS equipped with a Tekmar liquid sample concentrator (LSC 2000) was used for analysis.
• the calibration curve procedure was as follows. A freshly prepared 50 ppm TCE stock solution was obtained by dissolving 34.2 ⁇ l spectrophotometric grade TCE (Aldrich) in 20 ml HPLC grade methanol (Fisher) followed by dilution to a liter. Dilution of this solution (1000 ⁇ l : 1L) resulted in a 50 ppb TCE stock solution. All dilutions were accomplished using deionized water. A calibration curve was constructed by purging 1.0, 0.50, 0.20, 0.10, and 0.050 ppb TCE solutions.
• TCE in the sample is less that 500 ppb (EPA TCLP limit) characterizes it as a nonhazardous waste with respect to TCE.

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  • 1995-12-06 CA CA002207039A patent/CA2207039A1/en not_active Abandoned
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