CN101298039B - Preparation of chitosan molecular imprinting adsorbing agent - Google Patents

Abstract

The invention provides a preparation method for a print adsorbent of chitosan molecules, which relates to a preparation method for an adsorbent that can selectively remove perfluorooctane sulfonate (PFOS) in water. The preparation method adopts a molecular imprinting technique to construct a plurality of specific adsorption sites and the worthy adsorbent has remarkable selectivity adsorption to the PFOS in water. The method takes chitosan as raw material to prepare micro-cross linking chitosan beads; then the chitosan beads are printed with template molecules PFOS for 5 to 24 hours in an acid water solution, a mass ratio between the template molecules and the micro-cross linking chitosan beads is 0.005 to 0.06: 1, and reaction with a cross linker is carried out for 2 to12 hours after printing; the mass ratio between the volume of the cross linker and the micro-cross linking chitosan beads after being printed is 0.0125 to 0.119ml/g; finally, an organic solvent is used for eluting for 1 to 8 hours and the print adsorbent of chitosan molecules is obtained after freeze-drying. The adsorbent is suitable for adsorbing and removing PFOS in complicated water substances and is characterized by strong selectivity and being able to be reused.

Description

A kind of preparation method of chitosan molecularly imprinted adsorbent

technical field

The invention relates to a preparation method of a chitosan molecularly imprinted adsorbent. The adsorbent prepared by the method can selectively adsorb and remove perfluorooctane sulfonate (PFOS) in complex water bodies, and belongs to water Dealing with the field of adsorption technology.

Background technique

Perfluorooctane sulfonate (PFOS) is an important class of perfluorinated compounds, which are widely used in many fields as surfactants, antifouling agents, fire extinguishing foams and chemical intermediates. At the same time, PFOS is also the final degradation product of various perfluorinated compounds. In recent years, more and more researchers have studied and reported on the refractory, bioaccumulation, endocrine disrupting, toxicity and global distribution of PFOS. As a new candidate for persistent organic pollutants (POPs), PFOS has a maximum solubility of 570 mg/L in water, which makes them more potentially harmful to humans and the environment than other POPs. Therefore, it is particularly important to develop appropriate technology to effectively remove PFOS in water.

At present, only a few methods have been reported for the removal of PFOS, including sonication (EnvironmentalScience and Technology, 2005, 39, 3388-3392), reduction of zero-valent iron in subcritical water (EnvironmentalScience and Technology, 2006, 40, 1049-1054), reverse osmosis membrane (Environmental Science and Technology, 2006, 40, 7343-7349) and activated carbon adsorption (Organohalogen Compounds, 2007, 69, 2820-2823), etc. In addition to the shortcomings of the above methods, such as high price, high requirements for reaction conditions, or difficult regeneration, they do not have the ability to selectively remove PFOS. However, whether it is in natural water bodies or in industrial raw water such as semiconductors and electroplating, there are many other pollutants that exist in water bodies at the same time as PFOS, which will greatly reduce the removal effect of traditional technologies on PFOS. Therefore, selectivity plays a crucial role in the removal of PFOS in complex water bodies.

Molecular imprinting technology refers to the steps of interaction between template and monomer, cross-linking, polymerization, and elution of template molecules to finally prepare a polymer that can recognize the target in the spatial structure and adsorption site. The biggest feature of the adsorbent prepared by molecular imprinting method is that it has a high adsorption selectivity for the target substance. Although conventional adsorbents also have a certain adsorption effect on PFOS, in complex water bodies, due to the interference of other pollutants, their adsorption effect is often greatly reduced, and molecularly imprinted adsorbents can just make up for the shortcomings of conventional adsorbents. It can selectively remove PFOS in water.

Chitosan is the product of the removal of N-acetyl groups from chitin. Generally speaking, chitin with more than 55% of N-acetyl groups removed can be called chitosan. Chitosan has a wide range of raw materials for production, and has good biocompatibility, non-toxicity and biodegradability. In addition, chitosan contains a variety of functional groups such as hydroxyl and amino groups, which can be easily modified by cross-linking and grafting, making it an important environmentally friendly functional material. Utilizing the characteristic that chitosan is soluble in dilute acid but not in alkali, chitosan can be dissolved in low-concentration acetic acid, hydrochloric acid and other solutions, and then dropped into alkaline solution to obtain a hydrogel Chitosan pellets (Industrial and Engineering Chemistry Research, 1998, 37, 1454-1463). At present, this material has been applied in the fields of pollutant removal, enzyme immobilization and catalyst carrier. (In spite of this, we have not found that there are documents that use chitosan beads directly as functional bodies to prepare molecularly imprinted adsorbents, while the present invention utilizes chitosan beads as raw materials and successfully utilizes step-by-step cross-linked Methods A molecularly imprinted adsorbent capable of selectively and effectively removing PFOS from water was prepared.

Contents of the invention

The purpose of the present invention is to provide a preparation method of chitosan molecularly imprinted adsorbent for removal of PFOS in complex water bodies, through the interaction, cross-linking and elution of template molecules and functional polymers, on chitosan beads A large number of specific adsorption sites are constructed, so that the prepared adsorbent has excellent adsorption selectivity for PFOS.

Technical scheme of the present invention is as follows:

A preparation method of chitosan molecularly imprinted adsorbent is characterized in that the method is carried out as follows:

1) Dissolve chitosan in dilute acid to prepare chitosan solution, then drop into alkaline solution to granulate to obtain gelatinous chitosan pellets, mix with epichlorohydrin at 40-60°C React for 2-12 hours, the ratio of the volume of epichlorohydrin added to the mass of chitosan pellets is 0.0125-0.0278ml/g, and finally wash the micro-crosslinked chitosan pellets and store them in deionized water spare;

2) Add the micro-crosslinked chitosan beads to the acidic solution containing the template molecule PFOS for imprinting for 5-24 hours, the mass ratio of the added template molecule PFOS to the micro-crosslinked chitosan beads is 0.005:1-0.06 : 1, the pH value of the solution is always maintained at 2 to 4; after the blotting, react with the cross-linking agent at 40-60°C for 2-12 hours, the volume of the added cross-linking agent is the same as that of the micro-cross-linked chitosan beads after blotting The mass ratio is 0.0125～0.119ml/g;

3) Elute the chitosan beads obtained in step 2) with an eluent for 1 to 8 hours to remove template molecules, then repeatedly rinse with deionized water, and finally freeze-dry to constant weight to prepare chitosan molecularly imprinted adsorbent .

The crosslinking agent used in the present invention is epichlorohydrin or glutaraldehyde; the template molecule perfluorooctane sulfonate compound is perfluorooctane sulfonic acid, potassium perfluorooctane sulfonate or sodium perfluorooctane sulfonate ; The eluent is a mixed solution of acetone/alkali, methanol/alkali and other organic solvents with good solubility to PFOS and a mixed solution of alkali.

Compared with the prior art, the present invention has the following advantages and outstanding effects:

In traditional molecular imprinting technology, the interaction between template molecules and monomers, polymerization reaction and cross-linking reaction are usually carried out simultaneously, and in most cases the formed bulk polymer needs repeated grinding and sieving to obtain Molecularly imprinted adsorbents are required, and the process of grinding and sieving is often time-consuming and laborious. The present invention adopts a kind of natural macromolecular polymer-chitosan as the functional body, utilizes its property of being soluble in acid but not soluble in alkali to prepare chitosan pellets directly for imprinting, successfully avoiding final grinding, is A very simple and easy preparation method for molecularly imprinted adsorbent.

At present, several PFOS removal technologies reported in the literature are not specific for PFOS. In complex water bodies, they cannot effectively remove PFOS, but the chitosan molecularly imprinted adsorbent prepared by the present invention can provide good selectivity. In the selective adsorption experiment, the present invention utilizes the adsorbent to respectively adsorb various pollutants with equimolar concentration under the same adsorption condition. The results showed that the chitosan molecularly imprinted adsorbent had a removal rate of 47.9% for PFOS, while for the common pollutants 2,4-dichlorophenoxyacetic acid, perfluorooctanoic acid, sodium dodecylbenzenesulfonate, sodium pentachlorophenate and The removal rates of phenol are respectively 4.7%, 4.2%, 17.0%, 11.5% and 5.1%, which fully demonstrates that the adsorbent prepared by the present invention has good adsorption specificity and selectivity for PFOS. In the regeneration experiment, PFOS was easily washed off by the acetone/sodium hydroxide mixed solution, and the adsorption performance of the chitosan molecularly imprinted adsorbent hardly decreased after five consecutive uses.

In summary, the outstanding advantages of the present invention are that the preparation method is simple and easy, and the prepared chitosan molecularly imprinted adsorbent has high selectivity to target pollutants and good regeneration performance.

Description of drawings

Fig. 1 Removal rate of different pollutants in aqueous solution by chitosan molecularly imprinted adsorbent (MIP) and non-imprinted adsorbent (NIP).

Detailed ways

In the present invention, the desired adsorbent is prepared through a multi-step reaction of crosslinking-imprinting-recrosslinking. The role of the first cross-linking reaction is to slightly cross-link the chitosan pellets, giving them the property of being insoluble in acids. In the subsequent imprinting reaction, the amino groups of the micro-crosslinked chitosan beads were fully protonated in the acidic solution, and the template molecules were adsorbed to the amino groups by electrostatic interaction. When cross-linking again, a sufficient amount of cross-linking agent can fully cross-link chitosan molecules, thereby fixing the spatial structure of the polymer. In the final elution, the alkaline solution can easily deprotonate the amino group of chitosan, so that the template molecule is eluted from chitosan, while methanol, acetone, etc. have good solubility for PFOS Organic solvents can increase the elution effect. Due to the sufficient cross-linking, the spatial structure of the polymer is still maintained after elution, and the cavities left after the removal of the template molecules have memory and recognition functions for the target molecules, and become effective molecularly imprinted adsorbents. recognition site.

Concrete preparation method of the present invention is as follows:

1) Dissolve chitosan in dilute acid to prepare chitosan solution, then drop into alkaline solution to granulate to obtain gelatinous chitosan pellets, mix with epichlorohydrin at 40-60°C Micro-crosslinking reaction for 2-12 hours, the ratio of the volume of epichlorohydrin added to the mass of chitosan pellets is 0.0125-00278ml/g, and finally the micro-crosslinked chitosan pellets are washed and stored in a Deionized water for standby;

2) Add the micro-crosslinked chitosan beads to the acidic solution containing the template molecule PFOS for imprinting for 5-24 hours, the mass ratio of the added template molecule PFOS to the micro-crosslinked chitosan beads is 0.005:1-0.06 : 1, the pH value of the solution is always maintained at 2 to 4; after the blotting, react with the cross-linking agent at 40-60°C for 2-12 hours, the volume of the added cross-linking agent is the same as that of the micro-cross-linked chitosan beads after blotting The mass ratio is 0.0125～0.119ml/g, and the crosslinking agent used is epichlorohydrin or glutaraldehyde;

3) Elute the chitosan beads obtained in step 2) with an eluent for 1 to 8 hours to remove template molecules, then repeatedly rinse with deionized water, and finally freeze-dry to constant weight to prepare chitosan molecularly imprinted adsorbent ; The eluent can be a mixed solution of acetone/alkali, methanol/alkali and other organic solvents with good solubility to PFOS and a mixed solution of alkali.

The evaluation method of the chitosan molecularly imprinted adsorbent in the present invention mainly compares with the PFOS adsorption capacity of the non-imprinted adsorbent. Non-imprinted adsorbents do not add template molecules in the preparation, and other preparation methods are exactly the same as molecularly imprinted adsorbents.

The present invention measures adsorbent to the experimental method of PFOS adsorption capacity as follows: add a certain amount of PFOS solution in 250mL conical flask, adjust initial pH of solution, then add adsorbent, after adding bottle stopper, triangular flask is placed on 25 ℃ constant temperature shaking Adsorb in the bed at a speed of 130rpm for 36h (adsorption equilibrium has been reached), then filter with a 0.22μm membrane, measure the remaining PFOS content in the filtrate, and use the following formula to calculate the removal rate of pollutants by the adsorbent:

R=(C ₀ -C _e )/C ₀ ×100%

Among them: R is the removal rate (%); C ₀ is the initial concentration of pollutants (mg/L); C _e is the equilibrium concentration of PFOS after adsorption (mg/L).

Embodiment 1: 1.5g chitosan is dissolved in the acetic acid solution of 50ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 200ml and granulate, the chitosan obtained The pellet is about 36g, washed with 1ml epichlorohydrin at 60°C for 12h, and stored in deionized water for later use. Take 9g of micro-crosslinked chitosan beads and add them to 500mL of perfluorooctane potassium sulfonate acidic aqueous solution (400mg/L) for blotting for 5h, and the pH value of the solution is always kept at about 4. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 60° C. for 12 h. The epichlorohydrin solution contained 0.3 mL of epichlorohydrin and 10 ml of deionized water. Then, it was eluted with methanol/0.5M potassium hydroxide solution for 1 h to remove template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 62%, and that of non-imprinted adsorbent was 52%.

Embodiment 2: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 400ml and granulate, the chitosan obtained is small The ball is about 72g. After reacting with 0.9ml epichlorohydrin at 40°C for 2h, it is washed and stored in deionized water for later use. Take 4g of micro-crosslinked chitosan pellets and add them to 125mL of potassium perfluorooctane sulfonate in an acidic aqueous solution (400mg/L) for blotting for 5h, and the pH value of the solution is always kept at around 4. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 60° C. for 5 h. The epichlorohydrin solution contained 0.15 mL of epichlorohydrin and 10 ml of deionized water. Then, it was eluted with acetone/0.5M sodium hydroxide solution for 3 hours to remove the template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 60%, and that of non-imprinted adsorbent was 42%.

Embodiment 3: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 500ml and granulate, the chitosan obtained is small The ball is about 72g. After reacting with 2ml epichlorohydrin at 40°C for 12h, it is washed and stored in deionized water for later use. Take 3.36g of micro-crosslinked chitosan pellets and add them to 125mL of perfluorooctane sulfonate acidic aqueous solution (500mg/L) for imprinting for 13.5h, and the pH value of the solution is always maintained at about 4. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 40° C. for 12 h. The epichlorohydrin solution contained 0.4 mL of epichlorohydrin and 10 ml of deionized water. Then, it was eluted with methanol/0.5M sodium hydroxide solution for 3 hours to remove template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 50%, and that of non-imprinted adsorbent was 31%.

Embodiment 4: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 500ml and granulate, the chitosan obtained is small The ball is about 72g. After reacting with 2ml epichlorohydrin at 40°C for 12h, it is washed and stored in deionized water for later use. Take 4 g of micro-crosslinked chitosan pellets and add them to 50 mL of an acidic aqueous solution of potassium perfluorooctane sulfonate (400 mg/L) for blotting for 24 hours, and the pH of the solution is always maintained at around 4. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 40° C. for 12 h. The epichlorohydrin solution contained 0.05 mL of epichlorohydrin and 10 ml of deionized water. Then alternately eluted with acetone/0.5M sodium hydroxide solution for 8 hours to remove template molecules, and finally rinsed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 62%, and that of non-imprinted adsorbent was 42%.

Embodiment 5: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 500ml and granulate, the chitosan obtained is small The ball is about 72g. After reacting with 2ml epichlorohydrin at 40°C for 12h, it is washed and stored in deionized water for later use. Take 4 g of micro-crosslinked chitosan beads and add them to 500 mL of perfluorooctane potassium sulfonate acidic aqueous solution (400 mg/L) for 24 hours, and the pH value of the solution is always maintained at about 3. After the blotting, the chitosan pellets were added into the glutaraldehyde solution and reacted at 40° C. for 12 h. The glutaraldehyde solution contained 0.2 mL of glutaraldehyde and 10 ml of deionized water. Then, it was eluted with acetone/0.5M sodium hydroxide solution for 8 hours to remove template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 55%, and that of non-imprinted adsorbent was 54%.

Embodiment 6: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after being completely dissolved, be dripped in the sodium hydroxide (0.5M) solution of 500ml to granulate, the chitosan obtained is small The ball is about 72g, washed and stored in deionized water after reacting with 2ml epoxy for 12h at 40°C. Take 2g of micro-crosslinked chitosan pellets and add them to 250mL acidic aqueous solution of potassium perfluorooctane sulfonate (480mg/L) for 24h, and the pH value of the solution is always kept at about 2. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 40° C. for 12 h. The epichlorohydrin solution contained 0.1 mL of epichlorohydrin and 5 ml of deionized water. Then, it was eluted with pure acetone/0.5M sodium hydroxide solution for 8 hours to remove template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules. Put 0.05g of imprinted and non-imprinted adsorbents into a 250mL Erlenmeyer flask, then add 100mL of PFOS solution (pH=5) with a concentration of 200mg/L, and adsorb on a shaker at 130rpm for 36h (to reach equilibrium). The calculated removal rate of PFOS by imprinted adsorbent was 75%, while that of non-imprinted adsorbent was 29%.

Embodiment 7: 3g chitosan is dissolved in the acetic acid solution of 100ml (volume percentage 2%), after treating to dissolve completely, drop in the sodium hydroxide (0.5M) solution of 500ml and granulate, the chitosan obtained is small The ball is about 72g, washed and stored in deionized water after reacting with 2ml of cross-linking agent at 40°C for 12h. Take 4g of micro-crosslinked chitosan pellets and add them to 400mL of perfluorooctane potassium sulfonate acidic aqueous solution (450mg/L) for 12h, and the pH value of the solution is always kept at about 2. After the blotting, the chitosan pellets were added into the epichlorohydrin solution and reacted at 40° C. for 12 h. The epichlorohydrin solution contained 0.2 mL of epichlorohydrin and 10 ml of deionized water. Then, it was eluted with acetone/0.5M sodium hydroxide solution for 8 hours to remove template molecules, and finally washed repeatedly with deionized water, and freeze-dried to constant weight to obtain chitosan molecularly imprinted adsorbent. Non-imprinted sorbents were prepared in the same way, but without the addition of template molecules.

Put 0.01 g of imprinted and non-imprinted adsorbents obtained in Example 7 into a 250 mL Erlenmeyer flask, then add 100 mL of PFOS solution (pH=5) with a concentration of 50 mg/L, and adsorb in a shaker at 130 rpm for 36 h ( Achieve balance). The concentration of PFOS in the solution before and after adsorption was separated by Shimadzu high performance liquid chromatography and measured with a conductivity detector. The calculated removal rate of PFOS by imprinted adsorbent was 60%, and that of non-imprinted adsorbent was 28%.

Put 0.01 g of the imprinted adsorbent obtained in Example 7 into a 250 mL Erlenmeyer flask, and then add 100 mL of PFOS, 2,4-dichlorophenoxyacetic acid, perfluorooctanoic acid, and dodecylbenzenesulfonic acid at a concentration of 100 μmol/L Sodium, sodium pentachlorophenate or phenol solution (pH = 6), adsorbed in a shaking table with a rotation speed of 130rpm for 36h (to reach equilibrium). The calculated removal rate of imprinted adsorbent for PFOS was 47.9%, while for 2,4-dichlorophenoxyacetic acid (2,4-D), perfluorooctanoic acid (PFOA), sodium dodecylbenzenesulfonate (SDBS), The removal rates of other common pollutants such as sodium pentachlorophenate (PCP) and phenol (Phenol) were 4.7%, 4.2%, 17.0%, 11.5% and 5.1%, respectively, far below the removal rate of PFOS (Fig. 1) .

Claims (3)

1. chitosan molecule trace preparation of adsorbent method is characterized in that this method carries out as follows:

1) shitosan is dissolved in makes chitosan solution in the diluted acid, splash into subsequently that granulation obtains gelatinous shitosan bead in the alkaline solution, at 40～60 ℃ of following and little cross-linking reaction 2～12h of epoxychloropropane, add epoxychloropropane the ratio of volume and the quality of shitosan bead be 0.0125～0.0278ml/g, at last little crosslinked shitosan bead is cleaned and is left in the deionized water standby;

2) little crosslinked shitosan bead is joined trace 5～24h in the acid solution that contains template molecule PFOS based compound, add template molecule PFOS based compound and little cross-linked chitosan bead mass ratio be 0.005: 1～0.06: 1, the pH value of solution value remains at 2～4; Trace finishes the back and reacts 2～12h with crosslinking agent down at 40～60 ℃, add crosslinking agent volume and trace after the ratio of quality of little cross-linked chitosan bead be 0.0125～0.119ml/g; Used crosslinking agent is epoxychloropropane or glutaraldehyde; Used template molecule PFOS based compound is PFOS, PFOS potassium or PFOS sodium;

3) with step 2) the shitosan bead that obtains removes template molecule with eluent wash-out 1～8h, washes repeatedly with deionized water again, and last freeze drying makes chitosan molecule trace adsorbent to constant weight.

2. chitosan molecule trace preparation of adsorbent method according to claim 1, it is characterized in that: used eluent is for to have the organic solvent of good solubility and the mixed solution of alkali to template molecule.

3. chitosan molecule trace preparation of adsorbent method according to claim 2 is characterized in that: described organic solvent adopts acetone or methyl alcohol.

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