CN110665467A - Preparation method of straw-based adsorbent for adsorbing anions/cations - Google Patents

Abstract

The invention relates to a preparation method for adsorbing anionic/cationic straw-based adsorbents, belonging to the field of sewage purification treatment. In the invention, the straw is used as the raw material, and the straw is purified, subjected to an acetylation reaction, and then prepared into a straw-based powder material, and carbon disulfide and 2,3-epoxypropyl trisulfide are respectively grafted to the straw-based powder material. Methylammonium chloride to obtain anionic/cationic straw-based adsorbents. The straw-based adsorbent of the present invention can adsorb anions and cations simultaneously, and the adsorption effect is obvious. The adsorption equilibrium can be reached in 20 minutes. . The preparation process of the straw-based adsorbent for adsorbing anions/cations in the present invention is simple, the adsorption effect is obvious, the cost is low, and the adsorbent has wide application prospects.

Description

A kind of preparation method of adsorbing anionic/cationic straw-based adsorbent

technical field

The invention relates to a preparation method for adsorbing anionic/cationic straw-based adsorbents, belonging to the field of sewage purification treatment.

Background technique

At present, the treatment of water pollution is a major problem we are currently facing. There are many treatment methods for water pollution, and the method of adsorbent adsorption is one of the important methods. Polluted water contains many kinds of ions, of which anions and cations are the main part. In many current adsorbents, they are mainly aimed at the adsorption of a single ion, such as a single anion, or a single cation. It is of great significance if anions and cations can be adsorbed and removed at the same time. Based on this purpose, the present invention prepares an anion/cationic straw-based adsorbent, which can adsorb anions and cations in water at the same time.

Due to the low lignin content, low nutritional value and low calorific value, straw straw is not suitable for the main reuse method, and is incinerated or discarded in large quantities, which not only wastes a large amount of biomass energy, but also pollutes the environment. Water pollution has seriously affected human health, and water pollution control has become an urgent problem to be solved. This research will be meaningful if rice straw can be efficiently applied to the control of water pollution; in fact, the efficient utilization of biomass resources has become a research hotspot in today's scientific community. Rice straw contains a large amount of cellulose, hemicellulose, lignin and a small amount of crude protein, inorganic salts, etc. Among them, cellulose, hemicellulose and lignin contain a large amount of active hydroxyl groups, which provide a good opportunity for their chemical modification. In addition, the active hydroxyl group is also a good adsorption group. Application No. 201110247024.3 reports the preparation and use method of sulfur dioxide straw adsorbent. This invention is prepared by swelling, oxidation and amination modification of straw straw. The straw adsorbent prepared by this method is mainly used for the adsorption of sulfur dioxide gas. Harmful ions in water cannot be removed yet. Due to the unique structure and the universality of resources, straw straw has been widely used as an adsorbent to adsorb various water ions. However, due to its own structural characteristics, straw-based adsorbents have low density and are not easy to sink in water. After simple chemical modification, it is still difficult to change their floating characteristics in water; The adsorption capacity also needs to be further improved, and simple chemical modification is difficult to change this situation. In view of these unfavorable factors, the present invention intends to prepare rice straw as an adsorbent for powder materials, which can simultaneously adsorb anions/cations in a water body.

SUMMARY OF THE INVENTION

The pollution of heavy metal cations and organic dye anions in the water body is increasing day by day. In order to solve the problem of heavy metal cations and organic dye anions pollution in water bodies, the purpose of the present invention is to provide a straw-based adsorbent for adsorbing anions/cations. Preparation method, described method comprises the steps:

(1) Purification of straw straws: Wash straw straws with tap water for several times, crush the washed straw straws to 50-100 mesh with a pulverizer; use 0.1mol/L hydrochloric acid solution and 0.5mol/L hydrogen peroxide The sodium solution was soaked for 1 h successively, and washed with water until neutral; the washed straws were dried and used for later use.

(2) Preparation of acetylated rice straw: 5-10 g of the purified rice straw in step (1) was swollen in 50 mL of glacial acetic acid for 2 h, and then dissolved in a mixed solution of 50-100 mL of acetic anhydride and 50-100 mL of acetic acid, Add 2-5mL of 5% dilute sulfuric acid dropwise to the system, react at 50-70℃ for 2h, after the reaction, neutralize with 1-3g of anhydrous magnesium acetate, and then pour the above reactant into 800-1000mL of distilled water The acetylated straw straws are separated out, and finally the obtained acetylated straw straws are centrifuged and washed until neutral, and then vacuum dried.

(3) Preparation of emulsion: take 3-5 g of the acetylated straw straw material prepared in step (2) into a round-bottomed flask, add 20-40 mL of petroleum ether, and keep it on a constant temperature electromagnetic stirrer at 38-43° C. Stir and dissolve completely. When the acetylated straw is completely dissolved, add the mixed solution to a round-bottomed flask containing 2-5 mL of Ningru 32, and stir to mix evenly. The above mixed solution is slowly added to 50-100 mL of saturated aqueous stearic acid solution, and uniformly stirred with a magnetic rotor to obtain an oil-in-water (O/W) emulsion.

(4) Solidification of the straw-based powder material: under the condition of constant stirring, the emulsion prepared in step (3) is added to 300-1000 mL of ethyl acetate solvent, and the precipitate is obtained by constant stirring. The precipitation liquid is centrifuged, washed for many times and vacuum-dried at low temperature to obtain a straw-based powder material.

(5) Grafting carbon disulfide to the straw-based powder material: at 45-60 °C, take 3-5 g of the straw-based powder material prepared in step (4) into a three-necked flask, and mix 5-10 mL of CS ₂ and 1- 2g potassium carbonate was dissolved in 50-100mL tetrahydrofuran solution, and the solution was added dropwise to the three-necked flask containing the straw-based powder material within 1-2h. After the dropwise addition, the stirring reaction was continued for 2-3h, and then filtered and washed. and drying to obtain carbon disulfide grafted straw-based powder material.

(6) Preparation of straw-based adsorbent: at a temperature of 55-65 °C, take 1-2 g of the carbon disulfide-grafted straw-based powder material prepared in step (5) into a three-necked flask, and adjust the pH of the aqueous solution in the three-necked flask. value to 8-10, 20mL of 10-15% 2,3-epoxypropyltrimethylammonium chloride (EPC) aqueous solution was added dropwise to a three-necked flask containing carbon disulfide grafted straw-based powder material within 0.5-1h, dripping After the addition is completed, the stirring reaction is continued for 2-3 hours, followed by filtration, washing and drying to obtain a straw-based adsorbent for adsorbing anions/cations.

The chemical reactions involved in the above-mentioned preparation method of the straw-based adsorbent for absorbing anions/cations of the present invention are as follows:

The chemical reaction involved in step (5):

The chemical reaction involved in step (6):

Compared with the prior art, the present invention has the following beneficial effects:

(1) The adsorbent prepared by the present invention uses straw as the main raw material, which is a renewable biomass resource with low price, and its economic value can be greatly improved by using it efficiently.

(2) The adsorbent prepared by the present invention can simultaneously adsorb anions/cations, and the adsorption effect is obvious, and the adsorption equilibrium can be reached in 20 minutes. g.

(3) The preparation process of the straw-based adsorbent for adsorbing anions/cations in the present invention is simple, the adsorption effect is obvious, the cost is low, and it has a wide application prospect.

Detailed ways

Embodiment 1:

(1) Purification of rice straw: Wash the rice straw with tap water for many times, and crush the washed rice straw to 50 mesh with a pulverizer; use 0.1 mol/L hydrochloric acid solution and 0.5 mol/L sodium hydroxide solution Soak for 1 hour successively, wash with clean water until neutral; dry the washed straw for later use.

(2) Preparation of acetylated rice straw: 5 g of the purified rice straw in step (1) was swollen in 50 mL of glacial acetic acid for 2 hours, then dissolved in a mixed solution of 50 mL of acetic anhydride and 50 mL of acetic acid, and 2 mL of 5 mL was added dropwise to the system. % dilute sulfuric acid was reacted at 58°C for 2 hours. After the reaction was completed, neutralize it with 1 g of anhydrous magnesium acetate, then pour the above reactant into 1000 mL of distilled water to precipitate acetylated straw straws, and finally centrifuge the obtained acetylated straw straws. Rinse until neutral and vacuum dry.

(3) Preparation of emulsion: take 3 g of acetylated straw material prepared in step (2) into a round-bottomed flask, add 20 mL of petroleum ether, and keep stirring at 39°C on a constant-temperature electromagnetic stirrer to dissolve completely. When the acetylated straw is completely dissolved, add the mixed solution to a round-bottomed flask containing 2 mL of Ningru 32, and stir to mix evenly. The above mixed solution was slowly added to 50 mL of saturated aqueous stearic acid solution, and stirred uniformly with a magnetic rotor to obtain an O/W emulsion.

(4) Solidification of the straw-based powder material: under the condition of constant stirring, the emulsion prepared in step (3) was added to 800 mL of ethyl acetate solvent, and the precipitate was obtained by constant stirring. The precipitation liquid is centrifuged, washed for many times and vacuum-dried at low temperature to obtain a straw-based powder material.

(5) Grafting carbon disulfide to the straw-based powder material: at 50°C, take 3 g of the straw-based powder material prepared in step (4) and place it in a three-necked flask, and dissolve 5 mL of CS ₂ and 1 g of potassium carbonate in 100 mL of tetrahydrofuran solution , the solution was added dropwise to the three-necked flask containing the straw-based powder material within 1-2 hours, and the stirring reaction was continued for 2-3 hours after the dropwise addition, and then filtered, washed and dried to obtain carbon disulfide-grafted straw-based powder. body material.

(6) Preparation of straw-based adsorbent: at a temperature of 60 °C, take 2 g of the carbon disulfide-grafted straw-based powder material prepared in step (5) into a three-necked flask, and adjust the pH of the aqueous solution in the three-necked flask to 8- 10,20mL of 10% 2,3-epoxypropyltrimethylammonium chloride (EPC) aqueous solution was added dropwise to a three-necked flask containing carbon disulfide grafted straw-based powder material within 0.5-1h, and the stirring reaction was continued after the dropwise addition was completed. 2-3h, then filtered, washed and dried to obtain a straw-based adsorbent I for adsorbing anions/cations.

Embodiment 2:

(1) Purification of rice straw: Wash the rice straw with tap water for many times, and crush the washed rice straw to 50 mesh with a pulverizer; use 0.1 mol/L hydrochloric acid solution and 0.5 mol/L sodium hydroxide solution Soak for 1 hour successively, wash with clean water until neutral; dry the washed straw for later use.

(2) Preparation of acetylated rice straw: 10 g of the purified rice straw in step (1) was swollen in 50 mL of glacial acetic acid for 2 hours, then dissolved in a mixed solution of 100 mL of acetic anhydride and 100 mL of acetic acid, and 5 mL of 5 mL was added dropwise to the system. % dilute sulfuric acid was reacted at 61 °C for 2 hours. After the reaction, neutralize with 2 g of anhydrous magnesium acetate, and then pour the above reactant into 1000 mL of distilled water to precipitate acetylated straw straws. Finally, the obtained acetylated straw straws were centrifuged. Rinse until neutral and vacuum dry.

(3) Preparation of emulsion: Take 4 g of the acetylated straw material prepared in step (2) into a round-bottomed flask, add 25 mL of petroleum ether, keep stirring at 40°C on a constant temperature electromagnetic stirrer and dissolve completely. When the acetylated straw is completely dissolved, add the mixed solution to a round-bottomed flask containing 2.5 mL of Ningru 32, and stir to mix it evenly. The above mixed solution was slowly added to 80 mL of saturated aqueous stearic acid solution, and stirred uniformly with a magnetic rotor to obtain an O/W emulsion.

(4) Solidification of the straw-based powder material: under the condition of constant stirring, the emulsion prepared in step (3) was added to 1000 mL of ethyl acetate solvent, and the precipitate was obtained by constant stirring. The precipitation liquid is centrifuged, washed for many times and vacuum-dried at low temperature to obtain a straw-based powder material.

(5) Grafting carbon disulfide to the straw-based powder material: at 52°C, take 3 g of the straw-based powder material prepared in step (4) and place it in a three-necked flask, and dissolve 5 mL of CS ₂ and 1.5 g of potassium carbonate in 80 mL of tetrahydrofuran. In the solution, the solution is added dropwise to a three-necked flask containing the powder material of straw-based straw within 1-2 hours, and the stirring reaction is continued for 2-3 hours after the dropwise addition, and then filtered, washed and dried to obtain the carbon disulfide grafted straw-based straw. powder material.

(6) Preparation of straw-based adsorbent: at a temperature of 61°C, take 2.5 g of the carbon disulfide-grafted straw-based powder material prepared in step (5) into a three-necked flask, and adjust the pH value of the aqueous solution in the three-necked flask to 8 -10, 20mL of 15% 2,3-epoxypropyltrimethylammonium chloride (EPC) aqueous solution was added dropwise to a three-necked flask containing carbon disulfide grafted straw-based powder material within 0.5-1h, and continued stirring after the dropwise addition was completed The reaction was carried out for 2-3 h, followed by filtration, washing and drying to obtain a straw-straw-based adsorbent II for adsorbing anions/cations.

Embodiment 3:

(1) Purification of straw: Wash the straw with tap water for several times, and crush the washed straw to 100 mesh with a pulverizer; use 0.1 mol/L hydrochloric acid solution and 0.5 mol/L sodium hydroxide solution Soak for 1 hour successively, wash with clean water until neutral; dry the washed straw for later use.

(2) Preparation of acetylated rice straw: 8 g of the purified rice straw in step (1) was swollen in 50 mL of glacial acetic acid for 2 hours, then dissolved in a mixed solution of 80 mL of acetic anhydride and 80 mL of acetic acid, and 4 mL of 5 mL was added dropwise to the system. % dilute sulfuric acid was reacted at 60 °C for 2 hours. After the reaction was completed, neutralize with 3 g of anhydrous magnesium acetate, then pour the above reactant into 1000 mL of distilled water to precipitate acetylated straw straws, and finally centrifuge the obtained acetylated straw straws. Rinse until neutral and vacuum dry.

(3) Preparation of emulsion: Take 5 g of acetylated straw material prepared in step (2) into a round-bottomed flask, add 40 mL of petroleum ether, and keep stirring at 40°C on a constant-temperature electromagnetic stirrer to dissolve completely. When the acetylated straw is completely dissolved, add the mixed solution to a round-bottomed flask containing 5 mL of Ningru 32, and stir to mix evenly. The above mixed solution was slowly added to 100 mL of saturated aqueous stearic acid solution, and uniformly stirred with a magnetic rotor to obtain an O/W emulsion.

(4) Solidification of the straw-based powder material: under the condition of constant stirring, the emulsion prepared in step (3) was added to 900 mL of ethyl acetate solvent, and the precipitate was obtained by constant stirring. The precipitation liquid is centrifuged, washed for many times and vacuum-dried at low temperature to obtain a straw-based powder material.

(5) Grafting carbon disulfide from the straw-based powder material: at 52° C., take 4.5 g of the straw-based powder material prepared in step (4) and place it in a three-necked flask, and dissolve 10 mL of CS ₂ and 2 g of potassium carbonate in 100 mL of tetrahydrofuran. In the solution, the solution is added dropwise to the three-necked flask containing the straw-based powder material within 1-2 hours. After the dropwise addition, the stirring reaction is continued for 2-3 hours, and then filtered, washed and dried to obtain carbon disulfide grafted rice straw. base powder material.

(6) Preparation of straw-based adsorbent: at a temperature of 61 °C, take 2 g of the carbon disulfide-grafted straw-based powder material prepared in step (5) into a three-necked flask, and adjust the pH of the aqueous solution in the three-necked flask to 8- 10,20mL of 10% 2,3-epoxypropyltrimethylammonium chloride (EPC) aqueous solution was added dropwise to a three-necked flask containing carbon disulfide grafted straw-based powder material within 0.5-1h, and the stirring reaction was continued after the dropwise addition was completed. 2-3h, then filtered, washed and dried to obtain a straw-straw-based adsorbent III for adsorbing anions/cations.

The adsorption performance tests are carried out on the straw-based adsorbents I, II and III prepared by the present invention for adsorbing anions/cations:

a. Influence test of adsorption concentration on adsorption performance

Reactive red 195 solutions with mass concentrations of 20, 40, 100, 200, 300, 400, and 600 mg/L were prepared, 50 mL of each concentration was weighed, and the pH of the solution was calibrated to 7, and then 0.1 g of straw-based The adsorbent I was shaken at a constant temperature of 20°C for 2 hours, then filtered, and the filtrate was taken to measure the concentration change of reactive red 195 in the solution before and after adsorption. Using the same operation method, the adsorbents were replaced with straw-based adsorbents II, III, activated carbon and titanium dioxide, respectively, and the adsorption amounts were obtained as shown in Table 1.

Table 1 Adsorption performance of straw-based adsorbents I, II, III at different adsorption concentrations

It can be seen from Table 1 that under the same dye concentration, the adsorption capacity of the straw-based adsorbents I, II and III on the reactive dye reactive red 195 is significantly higher than that of activated carbon and titanium dioxide.

b. Influence test of adsorption temperature on adsorption performance

A reactive red 195 solution with a mass concentration of 300 mg/L was prepared, 50 mL of each concentration was weighed, and the pH of the solution was calibrated to 7, and then 0.1 g of straw-based adsorbent I was added, respectively, at 10 °C, 20 °C, and 30 °C. Under the conditions of ℃, 40 ℃ and 50 ℃, it was shaken at constant temperature for 2 hours, and then filtered, and the filtrate was taken to measure the concentration change of reactive red 195 in the solution before and after adsorption. Using the same operation method, the adsorbents were replaced with straw-based adsorbents II, III, activated carbon and titanium dioxide, respectively, and the adsorption amount was obtained as shown in Table 2.

Table 2 Adsorption performance of straw-based adsorbents I, II, III at different temperatures

It can be seen from Table 2 that at the same temperature, the adsorption capacity of the straw-based adsorbents I, II, and III on the reactive dye reactive red 195 is significantly higher than that of activated carbon and titanium dioxide. In addition, the adsorption capacity of the straw-based adsorbents I, II, III increased slightly with the increase of temperature.

c. Test of the effect of adsorption time on adsorption performance

A reactive red 195 solution with a mass concentration of 300 mg/L was prepared, 50 mL of each concentration was weighed, and the pH of the solution was calibrated to 7, and then 0.1 g of straw-based adsorbent I was added respectively, and the constant temperature was shaken for 10 min at 20 °C. , 20min, 30min, 40min, 50min, and then filtered, and the filtrate was taken to measure the concentration change of reactive red 195 in the solution before and after adsorption. Using the same operation method, the adsorbents were replaced by straw-based adsorbents II, III, activated carbon and titanium dioxide, respectively, and the adsorption amounts were obtained as shown in Table 3.

Table 3 Adsorption properties of straw-based adsorbents I, II, III after different adsorption times

It can be seen from Table 3 that the adsorption time of the straw-based adsorbents I, II, and III reached equilibrium at 20 min, while the adsorption equilibrium time of activated carbon and titanium dioxide was 30 min, indicating that the straw-based adsorbents I, II, and III could The dye adsorption is achieved in a short time.

d. Adsorption performance test for different kinds of organic dyes containing anions

Various dye solutions with a mass concentration of 300 mg/L were prepared, 50 mL of each concentration was weighed, and the pH of the solution was calibrated to 7. Then 0.1 g of straw-based adsorbent I was added, and the solution was shaken at a constant temperature of 20 °C for 2 hours. , and then filtered, and the filtrate was taken to measure the change of dye concentration in the solution before and after adsorption. Using the same operation method, the straw-based adsorbent I was replaced by the straw-based adsorbent II, III, activated carbon and titanium dioxide, respectively, and the adsorption capacity was obtained as shown in Table 4.

Table 4 Adsorption properties of straw-based adsorbents I, II, III for different kinds of anion-containing organic dyes

As can be seen from Table 4, for different kinds of organic dyes containing anions, such as: reactive dye reactive red 195, direct dye lake blue 71, direct dye red 4BS, acid dye blue 80, acid dye red 1, straw-based adsorption Agents I, II, and III all have strong adsorption properties.

e. Adsorption performance test for different kinds of metal cations

Various dye solutions with a mass concentration of 300 mg/L were prepared, 50 mL of each concentration was weighed, and the pH of the solution was calibrated to 7. Then 0.1 g of straw-based adsorbent I was added, and the solution was shaken at a constant temperature of 20 °C for 2 hours. , and then filtered, and the filtrate was taken to measure the change of dye concentration in the solution before and after adsorption. Using the same operation method, the straw-based adsorbent I was replaced by the straw-based adsorbent II, III, activated carbon and titanium dioxide, respectively, and the adsorption capacity was obtained as shown in Table 5.

Table 5 Adsorption properties of straw-based adsorbents I, II, III for different kinds of metal cations

It can be seen from Table 5 that for different kinds of metal cations, such as Ca ²⁺ , Zn ²⁺ , Cu ²⁺ , Cd ²⁺ , Hg ²⁺ , the straw-based adsorbents I, II, and III all have very good properties. Strong adsorption properties.

f. Adsorption performance test for aqueous solution containing both metal cations and anion-containing organic dyes

Prepare a mixed aqueous solution with a mass concentration of 300 mg/L of metal cations and 300 mg/L of anionic organic dyes, weigh 50 mL of each concentration, and the pH of the solution is calibrated to 7, and then add 0.1 g of straw-based adsorbent I, respectively, Under the condition of 20 ℃, constant temperature shaking for 2h, then filtration, the filtrate was taken to measure the change of dye concentration in the solution before and after adsorption. Using the same operation method, the adsorbents were replaced with straw-based adsorbents II, III, activated carbon and titanium dioxide, respectively, and the adsorption amount was obtained as shown in Table 6.

Table 6 Adsorption properties of straw-based adsorbents I, II, and III on aqueous solutions containing both metal cations and anions containing organic dyes

It can be seen from Table 6 that the straw-based adsorbents I, II, and III all have strong adsorption performance for aqueous solutions containing both metal cations and anion-containing organic dyes.

Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the inspiration of the present invention, those skilled in the art can make a variety of similar expressions under the premise of not violating the purpose and claims of the present invention. The transformations fall within the protection scope of the present invention.

Claims (1)

1. a method for preparing a straw-based adsorbent for adsorbing anions/cations, characterized in that the method comprises the steps: (1) Purification of straw straws: Wash straw straws with tap water for several times, crush the washed straw straws to 50-100 mesh with a pulverizer; use 0.1mol/L hydrochloric acid solution and 0.5mol/L hydrogen peroxide The sodium solution was soaked for 1 h successively, and washed with water until neutral; the washed straws were dried and used for later use. (2) Preparation of acetylated straw: take 5-10g of purified straw in step (1) and swell in 50mL of glacial acetic acid for 2h, then dissolve it in a mixed solution of 50-100mL of acetic anhydride and 50-100mL of acetic acid, Add 2-5mL of 5% dilute sulfuric acid dropwise to the system, react at 50-70℃ for 2h, after the reaction, neutralize with 1-3g of anhydrous magnesium acetate, and then pour the above reactant into 800-1000mL of distilled water The acetylated straw straws are separated out, and finally the obtained acetylated straw straws are centrifuged and washed until neutral, and then vacuum dried. (3) Preparation of emulsion: take 3-5 g of the acetylated straw straw material prepared in step (2) into a round-bottomed flask, add 20-40 mL of petroleum ether, and keep it on a constant temperature electromagnetic stirrer at 38-43° C. Stir and dissolve completely. When the acetylated straw is completely dissolved, add the mixed solution to a round-bottomed flask containing 2-5 mL of Ningru 32, and stir to mix evenly. The above mixed solution is slowly added to 50-100 mL of saturated aqueous stearic acid solution, and the mixture is uniformly stirred with a magnetic rotor to obtain an O/W type emulsion. (4) Solidification of the straw-based powder material: under the condition of constant stirring, the emulsion prepared in step (3) is added to 300-1000 mL of ethyl acetate solvent, and the precipitate is obtained by constant stirring. The precipitation liquid is centrifuged, washed for many times and vacuum-dried at low temperature to obtain a straw-based powder material. (5) Grafting carbon disulfide to the straw-based powder material: at 45-60 °C, take 3-5 g of the straw-based powder material prepared in step (4) into a three-necked flask, and mix 5-10 mL of CS ₂ and 1- 2g potassium carbonate was dissolved in 50-100mL tetrahydrofuran solution, and the solution was added dropwise to the three-necked flask containing the straw-based powder material within 1-2h. After the dropwise addition, the stirring reaction was continued for 2-3h, and then filtered and washed. and drying to obtain carbon disulfide grafted straw-based powder material. (6) Preparation of straw-based adsorbent: at a temperature of 55-65 °C, take 1-2 g of the carbon disulfide-grafted straw-based powder material prepared in step (5) into a three-necked flask, and adjust the pH of the aqueous solution in the three-necked flask. When the value reaches 8-10, 20mL of 10-15% 2,3-epoxypropyltrimethylammonium chloride (EPC) aqueous solution is added dropwise to a three-necked flask containing carbon disulfide grafted straw-based powder material within 0.5-1h, dripping After the addition is completed, the stirring reaction is continued for 2-3 hours, and then filtered, washed and dried to obtain a straw-based adsorbent for adsorbing anions/cations.