JP2007518559A - Method of making and using a hybrid anion exchanger for the selective removal of contaminant ligands from a liquid - Google Patents

Abstract

A polymer anion exchanger in which hydrated Fe (III) oxide (HFO) was irreversibly dispersed inside the exchanger beads was used as the host material. Since the anion exchanger has a positively charged quaternary ammonium functional group, anionic ligands such as arsenate, chromate, oxalate, phosphate, and phthalate penetrate into and out of the gel phase. Can be controlled by the Donan exclusion effect. As a result, HFO microparticles supported on an anion exchanger exhibit a much larger capacity in removing arsenic and other ligands compared to those supported on a cation exchanger. The loading of HFO particles is carried out by preliminarily loading an anion exchange resin with an oxidizing anion such as MnO ⁴⁻ or OCl 2 ⁻ and then passing the ferrous sulfate solution through the resin.

Description

  The present invention relates to the manufacture and application of hybrid anion exchangers for the selective removal of contaminants from liquids.

  It is widely accepted that the fixed bed adsorption process is simple in operation, requires virtually no start-up time, and is tolerant of variations in feed composition. However, in order for the fixed bed process to be feasible and economically competitive, the adsorbent must be highly selective for the target contaminant, must be durable, It must be easy to recycle and reuse efficiently.

  Ideally, removal of target contaminants should not cause significant changes in pH or influent composition. In this regard, amorphous and crystalline hydrated Fe oxides (HFO) are directed against As (III) and As (V) oxyacids and oxyanions through ligand exchange in the coordination sphere of structural Fe atoms. Strong adsorption affinity. Recent investigations using broad-area X-ray absorption fine structure (EXAFS) have confirmed that As (III) and As (V) species are selectively bound to the oxide surface through formation of inner sphere complexes. HFO particles also exhibit a high adsorption affinity for phosphate, natural organics, selenite and other anionic ligands. FIG. 1 shows examples of the binding of various solutes on hydrated Fe (III) oxide or HFO. Commonly encountered competing ions such as chloride or sulfate can only be adsorbed through Coulomb interactions or formation of outer sphere complexes. As a result, they exhibit a low adsorption affinity for HFO particles. In comparison, ligands such as arsenite, monovalent arsenate, divalent arsenate, and phosphate are strongly adsorbed through the formation of Lewis acid-base interactions or inner sphere complexes.

  The conventional synthesis process is simple but produces only very fine submicron HFO particles. The particles cannot be used in fixed beds, permeable reactive barriers or flow systems due to excessive pressure drop, low mechanical strength and unacceptable durability. To overcome this problem, strong acid cation exchangers have been modified to dope / disperse HFO particles for arsenic removal. Cation exchange resins and alginate loaded with iron have also been attempted for removal of selenium and arsenic oxyanions. Hydrated Fe (III) oxide (HFO) particles loaded on the cation exchanger can remove arsenate or phosphate, but the gel phase of the cation exchanger is due to the presence of sulfonic acid groups Since they are negatively charged, their removal capacity is reduced. As a result, arsenate or arsenic (V) oxyanion and phosphate are rejected due to Donan coion exclusion effect, and HFO particles dispersed in the gel phase are dissolved in anionic ligands for selective adsorption. Cannot approach.

  When a macroporous cation exchanger was used as the host material, the arsenic removal capacity was not high, but was on the order of 750 μg As / adsorbent g. However, when a gel-type cation exchanger was used to disperse the HFO particles, the resulting material was completely ineffective.

  FIG. 2 shows the column treatment eluate history when a gel-type cation exchanger was loaded with 8 percent HFO present as Fe. Arsenic breakthrough occurred almost immediately. As a result, the material had little arsenic removal capacity. We have observed that arsenate or other anionic ligands for selective adsorption are inaccessible when HFO particles are trapped inside a cation exchange site as illustrated in FIG. However, the dispersion of HFO particles in a cation exchanger material is a relatively simple process.

  Thus, it is an object of the present invention to provide a new and more effective medium for selectively removing arsenic species and other ligands from aqueous solutions and also to effect hydrated iron oxide on an anion exchange resin. Is to provide a way to load automatically.

  Unlike a cation exchanger, an anion exchanger has a positively charged functional group attached thereto. As a result, anionic ligands can easily penetrate into and out of the gel phase without encountering Donan's coion exclusion effect. If HFO particles are dispersed in polymeric anion exchanger beads, the arsenic or ligand removal capacity can be greatly increased. On the other hand, forming hydrated Fe (III) oxide inside an anion exchange resin presents a major challenge due to positively charged quaternary ammonium functional groups. As a result, until now, there has been no known method for successfully achieving dispersion of HFO particles within the anion exchanger of the polymer.

  In the synthesis of the selective adsorbent according to the present invention, a step of reacting a material exhibiting anion exchange behavior with an anionic oxidant to produce an intermediate, the intermediate and an oxidizable metal salt solution are reacted. Reacting, and as a result, precipitating and dispersing the metal salt through the intermediate by the action of an oxidizing agent to produce an adsorbent.

  The step of reacting a material exhibiting anion exchange behavior with an anionic oxidant is preferably carried out by passing a solution of the anionic oxidant through the material. The step of reacting the metal salt solution with the intermediate passes the salt solution through the intermediate, resulting in oxidation of the metal such that the metal is in a higher oxidation state than in the original salt. This is done by precipitating and dispersing other salts. After reacting the metal salt solution with the intermediate, a step of washing the adsorbent with an organic solvent, preferably acetone, and drying the adsorbent may be performed.

  In the preparation of the adsorbent, the results may be improved by repeating the steps of the reaction between the material exhibiting anion exchange behavior and the anionic oxidant and the reaction between the metal salt solution and the intermediate.

  The material exhibiting anion exchange behavior is preferably a polymeric anion exchange resin and may comprise weakly basic organic ion exchange resin beads comprising primary, secondary or tertiary amine groups, or mixtures thereof. Other preferred materials include strong base organic ion exchange resin beads containing quaternary ammonium groups with positively charged nitrogen atoms, and organic ion exchange resin beads having a polystyrene or polystyrene / divinylbenzene matrix.

  The preferred metal salt is ferrous salt solution and the preferred anionic oxidant is permanganate or hypochlorite

  The adsorbent thus produced contains a polymer anion exchange resin containing dispersed particles of iron oxygen-containing compounds, and is capable of selectively removing ligands from a liquid stream in contact with the adsorbent. Adsorbents remove ligands such as arsenate, arsenite, chromate, molybdate, selenite, vanadate from drinking water, groundwater, industrial process water, or industrial wastewater streams It is particularly effective.

  In a preferred embodiment, the adsorbent layer for selectively removing ligands from an aqueous solution comprises a solution containing oxidizing ions such as permanganate, persulfate, or hypochlorite, polymer anions. It is prepared by passing through an exchange resin layer. Thereafter, a solution of a ferrous salt, such as ferrous sulfate, is passed through the layer, thereby simultaneously desorbing the oxidizing anions and oxidizing the ferrous ions to ferric ions. This causes precipitation and uniform dispersion of solid hydrated ferric oxide inside the polymer anion exchange resin. For example, anionic ligands such as arsenate, chromate, oxalate, phosphate, and phthalate can penetrate into and out of the gel phase and are not governed by the Donan exclusion effect. As a result, HFO microparticles supported on anion exchangers, as compared to particles supported on cation exchangers, as well as other ligands, arsenate, arsenite, and other arsenic oxyanions. Shows a very large capacity in the removal of

  Another advantage of the present invention is that the physical properties of the anion exchange material can otherwise provide structural integrity to the brittle and weak material. As described above, by dispersing the HFO particles in the anion exchange material, it is possible to synthesize a layer exhibiting more excellent material characteristics than when the HFO particles themselves are granulated and aggregated. . The improvement in physical robustness afforded by the use of an anion exchange material allows the use of HFO particles in more demanding situations, such as higher pressures and increased flow. The improved physical robustness of the hybrid material also allows for efficient regeneration and reuse of the bed, and common backwashing and other maintenance in the processing of streams with hydrated metal oxides not supported by the substrate Reduce the need for

  Other objects, details and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the drawings.

Since Fe ³⁺ and Fe ²⁺ are cations, they are repelled by the positively charged functional groups of the anion exchanger and cannot be loaded onto the anion exchange resin. Thus, the techniques previously used for the dispersion of HFO particles within the cation exchanger beads are not applicable when anion exchanger beads are used as the host material. However, we have found that a series of steps can support HFO particles within an anion exchanger. Preferred examples thereof are as follows.

As a first step, a permanganate anion (MnO ₄ ⁻ ) is an anion exchange resin (eg, A-500P available from Pennsylvania, Bala Cynwyd, The Purolite Company, an anion having a quaternary ammonium functional group of the chloride type. Loaded on ion exchange resin). Loading of permanganate anions into the resin is performed by passing a potassium permanganate solution (500 mg / L KMnO ₄ ) through the layer.

This may be done, for example, by passing a 500 mg / L KMnO ₄ solution through the layer to cause the following reaction.

  Formula 2 is an anion exchange resin having a chloride type quaternary ammonium functional group.

  Of course, other manufacturer's anion exchange resins may be used. The particle size of the anion exchange resin is preferably in the range of 300 μm to 1000 μm.

The second stage is simultaneous permanganate desorption, Fe (II) oxidation and HFO formation inside the anion exchanger. During this phase, the permanganate loaded anion exchanger is contacted with a 5% ferrous sulfate solution. Desorption of MnO ₄ ⁻ with sulfuric acid, reduction of MnO ₄ ⁻ to MnO ₂ (s) and oxidation of Fe ²⁺ to Fe ³⁺ , and finally Fe (OH) ₃ (s) inside the anion exchanger beads Precipitation occurs according to:

Desorption of MnO ₄ ⁻ :

（上部バー及び（ｓ）は固層を示す。） Oxidation of Fe (II) and formation of ferric hydroxide:

(The upper bar and (s) indicate a solid layer.)

  The third stage is washing with acetone and drying. The second stage anion exchanger beads are washed with acetone and dried at 35 ° C. for 12 hours.

  The major stages of the process, the first and second stages, are shown in FIGS. 4A and 4B. These steps may be repeated to increase Fe (III) loading. Also, the manganese content inside the anion exchanger decreases with multiple cycles, which is a desirable phenomenon from an application point of view. In the third stage, the use of acetone reduces the dielectric constant of water and enhances the aggregation of HFO submicron particles through suppression of surface charge. The HFO mass was irreversibly trapped inside the spherical anion exchanger beads. Turbulence and mechanical agitation do not lead to significant loss of HFO particles.

  In our study, both gel and macroporous anion exchanger beads (Purolite A-400 and A-500P) were used. The loading mass of HFO on the anion exchanger varied from 10-15% as iron and the manganese content was less than 1% by mass of manganese. FIG. 5A shows hybrid anion exchanger (HAIX) particles. FIG. 5B is a scanning electron microscope (SEM) image of the matrix polymer bead section, and the presence of macropores is easily observed. FIG. 5C shows sliced HAIX particles containing HFO nanoparticles.

  The polymer anion exchanger beads exhibit excellent hydraulic and durability during fixed bed column processing, and the dispersed HFO microparticles act as active adsorbents for the targeted ligand.

  For purposes of illustration, the details of the steps performed in a typical laboratory level synthesis of hybrid anion exchanger particles are as follows.

  In a 4.0 liter container filled with 500 mg / L potassium permanganate solution, 30 g of Purolite anion exchanger resin was immersed in the solution with intermittent stirring for 30 minutes. The resin loaded with permanganate was rinsed twice with deionized water. The permanganate loaded resin was then immersed in 1.0 liter of 5.0% (w / v) ferrous sulfate solution and shaken for 4 hours. The modified resin (hybrid anion exchanger) was then rinsed several times with deionized water. These steps were repeated for the second and third cycles of iron loading. After each cycle, a sample of about 50 mg of hybrid anion exchanger was taken for iron and manganese content analysis.

  The hybrid resin was rinsed with deionized water and acetone and then dried in a 35 ° C. oven for 12 hours. The Purolite Company's macroporous and gel-type anion exchangers, both Purolite A-500P and A-400, were used as the matrix material. The iron and manganese loading of HAIX particles was found by applying twice 10% sulfuric acid for 24 hours at room temperature.

  The iron and manganese values at the end of each preparation cycle are shown below.

About HAIX-M (macroporous matrix resin)

＊ 乾燥されたハイブリッド陰イオン交換体ビーズに基づく About HAIX-G (gel matrix resin)

* Based on dried hybrid anion exchanger beads

  For HAIX-M, about 10 different batches and 5 batches of HAIX-G were synthesized. The iron content in HAIX-M after 3 cycles varied between 120-175 mgFe / g, while the iron content in HAIX-G was between 70-100 mgFe / g.

It was observed that the white color of the macroporous anion exchange resin changed to purple during loading with permanganate (MnO ₄ ⁻ ) ions. After adding ferrous sulfate solution, the purple color of the resin gradually changed to light brown. A uniform light brown characterizes the completion of formation of hydrated ferric oxide or HFO inside the resin beads. Approximately 4 hours are required to complete this phase.

In accordance with a similar experimental design, a laboratory test was conducted to prepare HAIX using sodium hypochlorite (NaOCl) solution. For illustration purposes, details of the steps performed in the synthesis of hybrid anion exchanger particles using hypochlorite ions (OCl ⁻ ) in the laboratory are given below.

  In a 4.0 liter container filled with 500 mg / L NaOCl solution, 30 g of macroporous anion exchanger resin was immersed in NaOCl solution with intermittent stirring for 30 minutes. The resin loaded with hypochlorite anion was then rinsed twice with deionized water. Thereafter, the resin loaded with hypochlorous acid was immersed in 1.0 liter of a 5.0% (w / v) ferrous sulfate solution and shaken for 4 hours. The modified resin (hybrid anion exchanger) was then rinsed several times with deionized water.

  The above steps were repeated for the second and third cycles of iron loading. After each cycle, a sample of approximately 50 mg of hybrid anion exchanger was taken for iron content analysis.

  The hybrid resin was rinsed with deionized water and acetone and then dried in a 35 ° C. oven for 12 hours. Iron loading was as follows:

＊ 乾燥されたハイブリッド陰イオン交換体ビーズに基づく

* Based on dried hybrid anion exchanger beads

  Since iron loading is significantly lower for hypochlorite compared to permanganate, HAIX performance evaluation and other adsorption studies during fixed bed column processing are permanganate as oxidants. Was carried out on the product obtained using

  The following experimental design was used in the performance evaluation of HAIX.

  A series of fixed bed experiments were performed to evaluate the removal capacity of HAIX As (III) and As (V). FIG. 6 illustrates the experimental setup, where contaminated water from the reservoir 20 was pumped by the pump 22 into the column 24 containing the HAIX beads 26 on the glass fiber layer 28. The regenerant in the reservoir 30 was pumped into the column by the pump 32. The eluate was collected in the eluate sample tube 34.

  Tests were also conducted using this test apparatus to verify the ability of HAIX to remove chromic acid, phosphoric acid and natural organics. The following results are noteworthy.

FIGS. 7A-7C give As (III) eluate history for three separate column processes under nearly ideal conditions, in FIG. 7A the chloride-type matrix anion exchanger Purolite A-500P 7B uses a macroporous cation exchanger loaded with HFO, and FIG. 7C uses a hybrid anion exchanger or HAIX. The ordinate (C / C ₀ ) represents the fraction of the influent concentration present at the column outlet.

As shown in FIG. 7A, the matrix anion exchanger was unable to remove As (III). The empty bed contact time (EBCT) was 4.5 minutes. The influent solution contained 100 μg / L As (III), 170 mg / L SO ₄ ²⁻ , 90 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ and had a pH of 6.2. Arsenic broke through immediately, long before sulfate breakthrough.

As shown in FIG. 7B, the cation exchanger loaded with HFO removed As (III) over a bed volume of 2000 or more and had a breakthrough concentration of 10 μg / L at a bed volume of about 2500. In this case, the EBCT was 3.1 minutes. The influent contained 100 μg / L As (III), 122 mg / L SO ₄ ²⁻ , 70 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ , and had a pH of 7.2.

In the experiment shown in FIG. 7C, the experimental parameters were the same as in FIG. 7A. That is, the EBCT is 4.5 minutes and the influent contains 100 μg / L As (III), 170 mg / L SO ₄ ²⁻ , 90 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ . The pH was 6.2. As illustrated in FIG. 7C, the anion exchanger loaded with HAIX or HFO treated the contaminated feed water close to 12,000 bed volumes before the eluent arsenic concentration reached 10 μg / L. . HAIX-M (macroporous hybrid anion exchanger) provided an As (III) removal capacity 6 times greater than HCIX-M (macroporous hybrid cation exchanger).

  In order to verify the hypothesis that the donan coion exclusion effect in the host material greatly affects the arsenic removal capacity of hydrated iron oxide particles, one gel-type cation exchanger (HCIX-G, using Purelite C-100) And one gel-type anion exchanger (HAIX-G, using Purelite A-400) was loaded with iron oxide particles. Subsequently, two column processes were performed separately for the purpose of arsenic removal using these two materials.

The Fe content of HAIX-G was 60 mg per 1 g of HAIX-G, and the Fe content of HCIX-G was 70 mg per 1 g of HCIX-G. The test was performed under ideal experimental conditions. The superficial liquid velocity (SLV) was 0.60 m / h and the EBCT was 3.9 minutes. The influent contained 100 μg / L As (V), 120 mg SO ₄ ²⁻ , 100 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ , and had a pH of 7.3.

  FIG. 8 shows the arsenic eluate history for two column processes. The hybrid cation exchanger practically did not remove arsenic even when the iron content was slightly higher. The hybrid anion exchanger, or HAIX, on the contrary, removed arsenic well over a layer volume of 10,000. All other conditions were ideal.

  Albuquerque, New Mexico's groundwater is contaminated with arsenic and contains high levels of dissolved silica. About 20 gallons of contaminated groundwater was collected from Albuquerque and column processing was performed using macroporous HAIX. The SLV was 0.83 m / h and the EBCT was 3.8 minutes. The influent contained 4.6 μg / L As (V), 33 mg / L silica and 0.46 mg / L phosphorous acid. The pH of the influent was 7.6.

  FIG. 9 shows the history of the eluate regarding arsenic removal. Although 33 mg / L of dissolved silica was present in the contaminated water, arsenic removal was very good. Arsenic breakthrough 10 ppb was observed after layer volume 7,200, while breakthrough from the silica column was within 500 layers.

  The HAIX-M column loaded with arsenic can be regenerated very efficiently in EBCT 5.6 minutes using a solution of 3% NaCl and 2% NaOH at pH 12.4. As shown in FIG. 10, over 90% of arsenic was desorbed within 10 layer volumes.

As illustrated in FIG. 11 which shows the eluate history of As (V) and Cr (VI) during column processing with a macroporous hybrid anion exchanger (HAIX-M), arsenate and chromate are It can be removed at the same time. Here, the EBCT was 3.8 minutes. The influent is a typical feed water, 100 μg / L As (V), 100 μg / L Cr (VI), 120 mg SO ₄ ²⁻ , 125 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ The pH was 7.1. The HAIX column was provided with a typical synthetic feed water. The HAIX column has been shown to be very efficient in removing both arsenic (V) and chromium (VI) simultaneously up to a bed volume of about 2000.

  When depleted, the column was regenerated with 2% NaOH and 3% NaCl. FIG. 12 shows the arsenic and chromium concentration profiles during HAIX-M regeneration in EBCT 3.9. Arsenate and chromate desorption has been shown to be very efficient.

FIG. 13 illustrates the removal of phosphoric acid using a hybrid anion exchanger. The HAIX column is fed with a feed solution containing phosphoric acid along with other commonly encountered anions. Specifically, the influent is 4.43 mg / L phosphoric acid (as P), 90 mg / L Cl ⁻ , 42 mg / L SO ₄ ²⁻ , 56 mg / L NO ₃ ⁻ , 78 mg / L HCO. ₃ ^-, hints, pH was 7.1. The EBCT was 3.3 minutes. As depicted in FIG. 13, the eluate history for P confirms HAIX's ability to selectively remove phosphate in the presence of other competing anions, namely chloride and sulfate.

One HAIX column was operated in three consecutive cycles. After each cycle, the column was regenerated with a solution of 2% NaOH and 3% NaCl. FIG. 14 shows the arsenic eluate history in two successive column processes using groundwater collected from contaminated sites in Ontario, Canada. The SLV was 1.58 m / h and the EBCT was 1.56 minutes. The influent was 430 μg / L As, 280 μg / L P, 3.0 mg / L TOC, 11.9 mg / L SO ₄ ²⁻ , 6.4 mg / L Cl ⁻ , 21.9 mg / L NO. ₃ ^- comprises, pH was 7.2. The arsenic eluate history was essentially the same. These results provide evidence that HAIX is recyclable and can be reused for multiple cycles without significant loss in arsenic removal capacity.

FIG. 15 shows the total iron concentration released during long column processing under the conditions of SLV 0.70 m / h and EBCT 4.5 min. The influent contained 100 μg / L As (III), 170 mg / L SO ₄ ²⁻ , 90 mg / L Cl ⁻ , 100 mg / L HCO ₃ ⁻ and had a pH of 6.2. The iron concentration at the column outlet was very low near the bed volume of 15,000 (less than 3 μg / L). The loss of iron from HAIX is negligible (30 μg / g HAIX-M) compared to its total capacity (120-150 mg Fe / g HAIX).

  With aging and continuous use, it is likely that amorphous HFO particles gradually crystallize, leading to the formation of goethite, hematite and the like. However, FIGS. 16A and 16B show a comparison of the X-ray diffraction (XRD) patterns of the newly prepared (FIG. 16A) and used (FIG. 16B) HAIX samples. Both patterns are very similar, with very little change. It is unlikely that any structural changes will occur in the HFO nanoparticles embedded in the anion exchanger.

  FIG. 17 shows the ability of the hybrid anion exchanger according to the present invention to remove vanadate from tap water containing 3 mg / L of vanadate as V. Two eluate histories are shown, one relating to the matrix anion exchanger and the other relating to the hybrid anion exchange material. As shown in the graph, vanadate begins to pass through the matrix anion exchanger almost immediately, whereas in the case of a hybrid anion exchange material, a measurable amount of vanadate has a bed volume of about 3000. It started to be detected only afterwards, and was kept at a level of 200 ppb or less in a layer volume of 8000.

  The performance of molybdate removal of the hybrid anion exchanger according to the present invention was also effective as shown by FIG. Two column processes are performed, one using a matrix anion exchanger, the other using a hybrid anion exchanger, and the influent consists of tap water containing 3 mg / L of molybdate as Mo. It was a thing. In the matrix anion exchanger, the molybdate began to break through at a layer volume of about 100, rising from a level of 100 μg / L at a layer volume of about 300 to a level of about 1700 μg / L at a layer volume of 1300. In contrast, in the case of a hybrid anion exchanger, the molybdate retained a level of 100 μg / L or less up to a layer volume of about 1000 and increased to only about 400 μg / L in the layer volume 1300.

  As described, many modifications can be made to the present invention. As previously indicated, any of a wide variety of anion exchange resins may be used for selective removal of ligands. For example, as a replacement for a strong base anion exchange resin having a quaternary ammonium functional group with a positively charged nitrogen atom, for example, a weak base organic ion exchange resin having a primary, secondary or tertiary amine group or a mixture thereof. Other anions such as beads, organic ion exchange resin beads with a polystyrene or polystyrene / divinylbenzene matrix, organic ion exchange resin beads with a polyacrylic acid matrix, organic or inorganic membranes, and polymer fibers or fibrous anion exchange materials. Ion exchange materials may be used.

  In principle, any anionic oxidant may be used instead of permanganate. For example, in addition to the previously described hypochlorites, other anionic oxidants such as persulfates, bromates, iodates and the like may be used.

  The intermediate produced by reacting the anion exchange material with an anionic oxidant is a solution of an oxidizable metal salt, preferably ferrous sulfate, ammonium ferrous sulfate, ferrous chloride or It may be reacted with a ferrous salt such as iron acetate. The hydrated iron oxide particles precipitated in the anion exchange material can take various forms such as hematite, goethite, magnetite, and iron hydroxide.

  Still other modifications may be made to the above apparatus and method without departing from the scope of the invention as defined in the following claims.

[Industrial use]
The present invention has applicability in the removal of contaminants from water, particularly in the treatment of drinking water, industrial process water, hazardous wastewater, and industrial wastewater, and in the regeneration of contaminated sites.

FIG. 6 is a schematic diagram illustrating the binding of various solutes to the top of hydrated Fe (III) oxide. 2 is a graph of arsenic eluate history during column processing using a hybrid cation exchanger gel. It is the schematic explaining why the HFO doped cation exchange resin cannot give sufficient arsenic adsorption capacity. It is the schematic explaining the 1st step in preparation of a hybrid anion exchanger adsorbent. It is the schematic explaining the 2nd step in preparation of a hybrid anion exchanger adsorbent. It is a macroporous hybrid anion exchange adsorbent particle image. It is a scanning electron microscope image of a base material polymer bead section. It is a scanning electron microscope image of a hybrid anion exchange bead section. It is the schematic of the apparatus regarding a fixed bed column process and a regeneration test. Eluate history for sulfate and arsenic during column treatment with chloride-type matrix anion exchanger, showing early arsenic breakthrough. It is a graph of the elution history of arsenic during column processing using a macroporous hybrid cation exchanger. It is a graph of the elution history of arsenic during column processing using a macroporous hybrid anion exchanger. It is a graph which compares the eluate log | history of an arsenic in a hybrid gel type cation exchanger and a hybrid gel type anion exchanger. 2 is a graph comparing the As (V) and silica breakthrough profiles during groundwater treatment using a newly prepared macroporous hybrid anion exchanger. 2 is a graph illustrating an arsenic concentration profile during typical regeneration of a hydrogen anion exchange resin. FIG. 4 is a graph of As (V) and Cr (VI) eluate history during column processing with a macroporous hybrid anion exchanger. FIG. 5 is a graph showing arsenic and chromium concentration profiles during macroporous hybrid anion exchanger regeneration. FIG. 6 is a graph showing breakthrough profiles of phosphorous acid and other anions during column processing with a macroporous hybrid anion exchanger. FIG. 4 is a graph showing the arsenic eluate history between two successive column treatments using a macroporous hybrid anion exchanger fed with the same contaminated groundwater. FIG. 6 is a graph showing the concentration of iron in the eluate during column processing using macroporous hybrid anion exchange particles. FIG. 2 is an X-ray diffraction diagram of newly prepared hybrid anion exchange particles. FIG. 3 is an X-ray diffraction diagram of a hybrid anion exchange particle used. It is a graph which shows the comparison of the eluate log | history of a vanadate regarding a hybrid anion exchanger and a base material anion exchanger. It is a graph which shows the comparison of the eluate log | history of a molybdate regarding a hybrid anion exchanger and a base material anion exchanger.

Explanation of symbols

20 Reservoir 22 Pump 24 Column 26 HAIX beads 28 Glass fiber layer 30 Reservoir 32 Pump 34 Eluate sample tube

Claims (19)

  A method for synthesizing a selective adsorbent, comprising: reacting a material exhibiting anion exchange behavior with an anionic oxidant to produce an intermediate; and a solution of the intermediate and a metal salt. And wherein the salt is oxidizable and, as a result, precipitates and disperses the metal salt over the range of the intermediate by the action of the oxidant to produce an adsorbent. Of synthetic adsorbent.   The step of reacting the material exhibiting anion exchange behavior with an anionic oxidant is performed by passing a solution of the anionic oxidant through the material, and reacting a metal salt solution with the intermediate The method of claim 1, wherein the method is performed by passing the salt solution through the intermediate.   2. The method of claim 1 wherein the step of reacting a metal salt solution with the intermediate is followed by washing the adsorbent with an organic solvent.   The method of claim 1, wherein the step of washing the adsorbent with acetone is performed following the step of reacting a metal salt solution with the intermediate.   The method of claim 1, wherein the step of washing and drying the adsorbent is performed following the step of reacting a metal salt solution with the intermediate.   In the preparation of the selective adsorbent, the step of reacting a material exhibiting anion exchange behavior with an anionic oxidant and the step of reacting a solution of a metal salt with the intermediate are repeated. The method of claim 1.   The method of claim 1, wherein the material exhibiting anion exchange behavior is a polymer anion exchange resin.   The method of claim 1 wherein the material exhibiting anion exchange behavior comprises weak base organic ion exchange resin beads having primary, secondary or tertiary amine groups or mixtures thereof.   The method of claim 1, wherein the material exhibiting anion exchange behavior comprises strong base organic ion exchange resin beads having a quaternary ammonium group with a positively charged nitrogen atom.   The method of claim 1, wherein the material exhibiting anion exchange behavior comprises organic ion exchange resin beads having a polystyrene or polystyrene / divinylbenzene matrix.   The method of claim 1, wherein the precipitated and dispersed metal salt is an oxygen-containing compound of iron.   The method of claim 1, wherein the metal salt solution is a solution of ferrous salt.   The method of claim 1, wherein the anionic oxidant is permanganate.   The method of claim 1, wherein the anionic oxidant is hypochlorite.   An adsorbent for selectively removing a ligand from a liquid, the adsorbent comprising a polymer anion exchange resin containing dispersed particles of an iron-containing compound of iron.   A method of removing contaminants from a liquid stream, wherein the liquid stream is contacted with an adsorbent comprising an anion exchange material infiltrated with HFO.   The method of claim 16, wherein the contaminant is a ligand.   17. The method of claim 16, wherein the contaminant is a ligand comprising one or more anions from the group consisting of arsenate, arsenite, chromate, molybdate, selenite and vanadate. . 17. The method of claim 16, wherein the liquid stream is a drinking water, groundwater, industrial process water or industrial wastewater liquid stream.

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