Preparation of bentonite-based composite adsorption material and application of bentonite-based composite adsorption material in sewage treatment

Abstract

The invention discloses preparation of a bentonite-based composite adsorption material and application of the bentonite-based composite adsorption material in sewage treatment. The preparation comprises the following steps: preparing modified bentonite; preparing modified biomass charcoal; mixing the modified bentonite and the modified biomass charcoal, and performing ball milling to obtain a mixture A; performing pressure-maintaining pressing on the mixture A by using a tablet press, and grinding to obtain a mixture B; the mixture B is subjected to heat treatment in the nitrogen atmosphere, naturally cooled to the room temperature and ground, the bentonite-based composite adsorption material is obtained, and the bentonite-based composite adsorption material is used for adsorbing heavy metal ions and organic pollutants in sewage. The bentonite-based composite adsorption material prepared by the invention has excellent adsorption capacity on heavy metal ions and organic pollutants in sewage.

Description

Technical Field

[0001] The present invention belongs to the technical field of bentonite adsorption materials. Specifically, the present invention relates to the preparation of a bentonite-based composite adsorption material and its application in sewage treatment. Background Art

[0002] With the rapid economic development, the problem of water pollution has become increasingly severe, seriously threatening human health and sustainable development. Sewage treatment can be divided into three types according to its function: physical method, biological method, and chemical method. Among them, the physical adsorption method removes pollutants from sewage through the interaction between the adsorption material and the pollutants in the sewage. Due to its advantages such as simple operation, high removal efficiency, and low cost, it is widely used. Its adsorption effect mainly depends on the selected adsorption material. Currently, the adsorption materials used for sewage treatment mainly include activated carbon, diatomite, bentonite, resin, and nanomaterials, etc.

[0003] Bentonite is a clay mineral mainly composed of montmorillonite, which is widely used in industrial, agricultural, environmental protection and other fields due to its unique physical and chemical properties. Bentonite has properties such as non-toxicity, water absorption, adsorption, and ion exchange, and is inexpensive, and can be used for sewage treatment to adsorb heavy metals, organic pollutants, etc. However, in the actual application process, the adsorption capacity of bentonite is limited. Therefore, the development of a new type of composite adsorption material based on bentonite to improve its adsorption capacity is of great significance for water pollution treatment. Summary of the Invention

[0004] One object of the present invention is to solve at least the above problems and / or defects, and provide at least the advantages described hereinafter.

[0005] To achieve these objects and other advantages of the present invention, a preparation method of a bentonite-based composite adsorption material is provided, including the following steps:

[0006] Step 1, prepare modified bentonite;

[0007] Step 2, prepare modified biochar;

[0008] Step 3, mix the modified bentonite and the modified biochar, and ball mill to obtain mixture A;

[0009] Step 4, use a tablet press to perform pressure holding and pressing on mixture A, and grind to obtain mixture B;

[0010] Step 5, perform heat treatment on mixture B under a nitrogen atmosphere, naturally cool to room temperature, and grind to obtain the bentonite-based composite adsorption material.

[0011] Preferably, the preparation method of the modified bentonite includes the following steps:

[0012] S11. Dissolve bentonite in deionized water, purify it, dry it, grind it through a 50 - 200 mesh sieve to obtain bentonite powder.

[0013] S12. Add the bentonite powder to hydrochloric acid aqueous solution, stir at a constant temperature, filter, wash, dry, and grind it to obtain pretreated bentonite.

[0014] S13. Add the pretreated bentonite to deionized water, disperse it evenly, then add sodium citrate and polyvinylpyrrolidone, stir at a constant temperature, then add cetyltrimethylammonium bromide solution, continue stirring, let it stand at room temperature, filter, wash, dry, and grind it to obtain modified bentonite.

[0015] Preferably, the preparation method of the modified biochar includes the following steps:

[0016] S21. Grind corn straw, add it to deionized water, heat it up, dropwise add sodium hypochlorite while stirring, after the addition is complete, continue stirring, cool to room temperature, adjust the pH with hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind it to obtain modified straw powder.

[0017] S22. Grind and mix the modified straw powder and pseudoboehmite evenly, pyrolyze it under a nitrogen atmosphere, naturally cool to room temperature, and grind it to obtain modified biochar.

[0018] Preferably, in S12, the mass - volume ratio of the bentonite powder to the hydrochloric acid aqueous solution is 1 g:5 - 10 mL; the concentration of the hydrochloric acid aqueous solution is 1 - 10 wt%; the temperature of constant - temperature stirring is 50 - 70 °C, the time is 8 - 12 h; grind it through a 50 - 200 mesh sieve.

[0019] Preferably, in S13, the mass - volume ratio of the pretreated bentonite to deionized water is 1 g:5 - 20 mL; the mass ratio of the pretreated bentonite, sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.2 - 0.6:0.1 - 0.5:0.3 - 0.6; the concentration of the cetyltrimethylammonium bromide solution is 1 - 10 wt%; the temperature of constant - temperature stirring is 50 - 70 °C, the time is 0.5 - 2 h; the temperature of continuous stirring is 70 - 90 °C, the time is 1 - 3 h; let it stand at room temperature for 12 - 36 h; grind it through a 50 - 200 mesh sieve.

[0020] Preferably, in S21, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:5 - 15:0.1 - 0.5; heat it up to 30 - 50 °C; after the addition is complete, continue stirring for 20 - 40 min; the concentration of the hydrochloric acid aqueous solution is 1 - 10 wt%, adjust the pH to 2 - 4; grind it through a 50 - 200 mesh sieve.

[0021] Preferably, in S22, the mass ratio of the modified straw powder to the pseudoboehmite is 3:0.5 - 1.5; the pyrolysis temperature is 700 - 900 °C, the time is 1 - 3 h; and it is ground through a 50 - 200 mesh sieve.

[0022] Preferably, in the third step, the mass ratio of the modified bentonite to the modified biochar is 7:2 - 4; the specific parameters of ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 5 - 15:1, the rotation speed is 200 - 400 rpm, and the time is 1 - 2 h.

[0023] Preferably, in the fourth step, the specific method of pressure holding and pressing is: using a tablet press for pressing, the pressure of the tablet press is 10 - 40 Mpa, the pressure holding time is 2 - 5 min; and it is ground through a 50 - 200 mesh sieve.

[0024] Preferably, in the fifth step, the specific method of heat treatment is: heating at a heating rate of 3 - 8 °C / min to 400 - 600 °C and holding for 2 - 4 h; and it is ground through a 50 - 200 mesh sieve.

[0025] Application of a bentonite-based composite adsorbent material prepared by the preparation method as described above in sewage treatment, wherein the bentonite-based composite adsorbent material is used for adsorbing heavy metal ions and organic pollutants.

[0026] Application of a bentonite-based composite adsorbent material prepared by the preparation method as described above in sewage treatment, wherein the bentonite-based composite adsorbent material is used for preparing a bentonite-based composite membrane, and the bentonite-based composite membrane is used for adsorbing heavy metal ions and organic pollutants.

[0027] Preferably, the preparation method of the bentonite-based composite membrane includes the following steps:

[0028] Step 1: Take polyimide ether imide ketone and polyvinyl alcohol according to a mass ratio of 4 - 8:1, add them to dimethyl sulfoxide, and stir at a constant temperature in a water bath at 70 - 90 °C for 1 - 3 h to obtain a mixed solution with a polyimide ether imide ketone concentration of 5 - 15 wt%;

[0029] Step 2: Grind the bentonite-based composite adsorbent material through a 1000 mesh sieve, then add it to the mixed solution, stir at a constant temperature in a water bath at 50 - 70 °C for 2 - 4 h, and then ultrasonicate for 1 - 2 h to obtain a casting solution; wherein, the mass ratio of the bentonite-based composite adsorbent material to the polyimide ether imide ketone in Step 1 is 1 - 3:5;

[0030] Step 3: Pour the casting solution onto a glass plate, and use the solution casting method to form a film, and dry it to obtain a bentonite-based composite membrane.

[0031] The present invention has at least the following beneficial effects: The present invention provides a preparation method of a bentonite-based composite adsorbent material. First, the bentonite is modified. The bentonite is purified to remove impurities, then treated in an acidic solution to increase the surface roughness of the bentonite, increase its specific surface area and active sites, and then treated with sodium citrate, polyvinylpyrrolidone and cetyltrimethylammonium bromide to improve its dispersibility and stability, introduce abundant functional groups, and effectively enhance its adsorption capacity and reaction activity. Then, the biomass carbon is modified to improve its dispersibility, adsorption capacity and reaction activity. Finally, the modified bentonite and the modified biomass carbon are compounded, and through ball milling, pressure holding pressing and heat treatment, a uniform, stable and tight adsorption network structure is formed. The obtained bentonite-based composite adsorbent material has excellent adsorption capacity for heavy metal ions and organic pollutants in sewage. In addition, the bentonite-based composite membrane prepared by using the bentonite-based composite adsorbent material of the present invention further improves the adsorption capacity for heavy metal ions and organic pollutants in sewage, and after the adsorption is completed, compared with the powder adsorbent material, the composite membrane is easier to separate and recycle.

[0032] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. Detailed implementation manners

[0033] The following further detailed description of the present invention is provided to enable those skilled in the art to implement it with reference to the text of the specification.

[0034] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0035] Example 1

[0036] A preparation method of a bentonite-based composite adsorbent material includes the following steps:

[0037] Step 1: Prepare modified bentonite:

[0038] S11. Dissolve natural calcium-based bentonite in deionized water, dry it at 80 °C after purification, grind it through a 100-mesh sieve to obtain bentonite powder.

[0039] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stir at 60 °C for 10 h, then filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain pretreated bentonite.

[0040] S13. Add the pretreated bentonite to deionized water at a mass-to-volume ratio of 1 g:10 mL, disperse it evenly, then add sodium citrate and polyvinylpyrrolidone, stir at 60 °C for 1 h, add a 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let it stand at room temperature for 24 h, filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain modified bentonite; among them, the mass ratio of the pretreated bentonite, sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0041] Step Two. Prepare modified biomass carbon:

[0042] S21. Grind corn straw through a 100-mesh sieve, add it to deionized water, dropwise add sodium hypochlorite while stirring at 40 °C. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with a 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 100-mesh sieve to obtain modified straw powder; among them, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0043] S22. Grind and mix the modified straw powder and pseudoboehmite evenly at a mass ratio of 3:1. Under a nitrogen atmosphere, heat it to 800 °C at a heating rate of 5 °C / min and hold for 2 h, then naturally cool to room temperature and grind through a 100-mesh sieve to obtain modified biomass carbon;

[0044] Step Three. Mix the modified bentonite and modified biomass carbon at a mass ratio of 7:3, and ball mill for 1 h to obtain mixture A; among them, the specific parameters of the ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0045] Step Four. Use a tablet press to press mixture A, set the pressure to 20 MPa, hold the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0046] Step Five. Heat mixture B in a nitrogen atmosphere to 500 °C at a heating rate of 5 °C / min and hold for 3 h, then naturally cool to room temperature and grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material.

[0047] Example 2

[0048] A preparation method of a bentonite-based composite membrane, comprising the following steps:

[0049] Step 1. Take polyimine ether imine ketone and polyvinyl alcohol at a mass ratio of 5:1, add them to dimethyl sulfoxide, and stir at a constant temperature of 80 °C in a water bath for 2 h to obtain a mixed solution with a polyimine ether imine ketone concentration of 10 wt%;

[0050] Step 2: Grind the bentonite-based composite adsorbent prepared in Example 1 through a 1000-mesh sieve, then add it to the mixed solution, stir it at a constant temperature in a 60°C water bath for 3 h, and then ultrasonicate it at 300 W and 60 kHz for 1 h to obtain a casting solution; wherein, the mass ratio of the bentonite-based composite adsorbent to the polyimide ether imidone in Step 1 is 2:5;

[0051] Step 3: Pour the casting solution onto a smooth glass plate, and prepare a film by the solution casting method, and dry it at 60°C to obtain a bentonite-based composite film with a thickness of 180 μm;

[0052] Among them, the preparation method of the polyimide ether imidone refers to the preparation method of Chinese Patent CN118681423A: Take a clean single-necked flask, install a magnetic stirrer and seal it, evacuate the inside of the flask under heating, and fill it with high-purity nitrogen after cooling, and cycle three times to remove impurity gases; Under nitrogen protection, add reactants 4,4'-dibromobenzophenone, 4,4'-diaminodiphenyl ether, catalyst Pd 2 (dba) 3 , sodium tert-butoxide, 1,1'-binaphthalene-2,2'-diphenylphosphine and N,N'-dimethylacetamide into the flask in a molar volume ratio of 1 mmol:1 mmol:0.01 mmol:2.8 mmol:0.03 mmol:2 mL in sequence, stir evenly, heat up to 100°C, keep warm for 4 h, then heat up to 160°C, keep warm for 24 h, and naturally cool to room temperature; Drop the liquid substance in the flask into distilled water to promote the precipitation of solid precipitate, filter and collect the precipitate, and then wash the precipitate repeatedly with distilled water to thoroughly wash away the residual solvent and other impurities; Dissolve the washed precipitate in N,N'-dimethylacetamide again, filter, and drop the filtrate into methanol to cause the secondary precipitation of the solid. Repeat the above dissolution-precipitation process three times to ensure the high purification of the product. Filtering operation is carried out after each precipitation; Finally, vacuum-dry the obtained precipitate at 80°C to obtain a pale yellow powder, which is polyimide ether imidone.

[0053] Comparative Example 1

[0054] A preparation method of a bentonite-based composite adsorbent includes the following steps:

[0055] Step 1: Prepare modified biochar:

[0056] S21: Grind corn straw through a 100-mesh sieve, add it to deionized water, drop sodium hypochlorite while stirring at 40°C. After dropping, stir for 30 min, cool to room temperature, adjust the pH to 3 with 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 100-mesh sieve to obtain modified straw powder; wherein, the mass ratio of corn straw, deionized water and sodium hypochlorite is 1:10:0.2;

[0057] S22. The modified straw powder and pseudoboehmite are ground and mixed evenly at a mass ratio of 3:1. Under a nitrogen atmosphere, the temperature is raised to 800 °C at a heating rate of 5 °C / min and held for 2 h, then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0058] Step two. Mix the natural calcium-based bentonite and the modified biochar at a mass ratio of 7:3 and ball-mill for 1 h to obtain mixture A; among them, the specific parameters of the ball-milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0059] Step three. Use a tablet press to press mixture A, set the pressure to 20 MPa, hold the pressure for 2 min, grind through a 200-mesh sieve to obtain mixture B;

[0060] Step four. Heat mixture B in a nitrogen atmosphere to 500 °C at a heating rate of 5 °C / min and hold for 3 h, then naturally cool to room temperature, and grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material.

[0061] In this comparative example, unmodified bentonite is used, and the remaining steps are the same as those in Example 1.

[0062] Comparative Example 2

[0063] A preparation method of a bentonite-based composite adsorbent material includes the following steps:

[0064] Step one. Prepare modified bentonite:

[0065] S11. Dissolve the natural calcium-based bentonite in deionized water, purify it, dry it at 80 °C, and grind through a 100-mesh sieve to obtain bentonite powder;

[0066] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stir at 60 °C for 10 h, then filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain pretreated bentonite;

[0067] S13. Add the pretreated bentonite to deionized water at a mass-to-volume ratio of 1 g:10 mL, disperse it evenly, then add sodium citrate and polyvinylpyrrolidone, stir at 60 °C for 1 h, then add a 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let it stand at room temperature for 24 h, filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain modified bentonite; among them, the mass ratio of the pretreated bentonite, sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0068] Step two. Prepare biochar:

[0069] S21. Grind the corn straw through a 100-mesh sieve, add it to deionized water, and dropwise add sodium hypochlorite while stirring at 40 °C. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with a 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, grind through a 100-mesh sieve to obtain modified straw powder; wherein, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0070] S22. Under a nitrogen atmosphere, heat the modified straw powder at a heating rate of 5 °C / min to 800 °C and hold for 2 h, then naturally cool to room temperature, grind through a 100-mesh sieve to obtain biochar;

[0071] Step 3. Mix the modified bentonite and biochar in a mass ratio of 7:3, and ball mill for 1 h to obtain mixture A; wherein, the specific parameters of the ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0072] Step 4. Use a tablet press to press mixture A, set the pressure to 20 MPa, hold the pressure for 2 min, grind through a 200-mesh sieve to obtain mixture B;

[0073] Step 5. Under a nitrogen atmosphere, heat mixture B at a heating rate of 5 °C / min to 500 °C and hold for 3 h, then naturally cool to room temperature, grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material.

[0074] In this comparative example, unmodified biochar is used, and the remaining steps are the same as those in Example 1.

[0075] Comparative Example 3

[0076] A preparation method of a bentonite-based composite adsorbent material includes the following steps:

[0077] Step 1. Prepare modified bentonite:

[0078] S11. Dissolve natural calcium-based bentonite in deionized water, purify it, dry it at 80 °C, and grind through a 100-mesh sieve to obtain bentonite powder;

[0079] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stir at 60 °C for 10 h, then filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain pretreated bentonite;

[0080] S13. Add the pretreated bentonite to deionized water at a mass-to-volume ratio of 1 g:10 mL, disperse it evenly, then add polyvinylpyrrolidone, stir at 60 °C for 1 h, add a 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let it stand at room temperature for 24 h, filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain modified bentonite; wherein, the mass ratio of the pretreated bentonite, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.2:0.5;

[0081] Step Two: Prepare modified biochar:

[0082] S21. Grind corn straw through a 100-mesh sieve, add it to deionized water, dropwise add sodium hypochlorite while stirring at 40 °C. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with a 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 100-mesh sieve to obtain modified straw powder; wherein, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0083] S22. Grind and mix the modified straw powder and pseudoboehmite evenly at a mass ratio of 3:1. Under a nitrogen atmosphere, heat it to 800 °C at a heating rate of 5 °C / min and hold for 2 h, then naturally cool to room temperature and grind through a 100-mesh sieve to obtain modified biochar;

[0084] Step Three: Mix the modified bentonite and modified biochar at a mass ratio of 7:3 and ball-mill for 1 h to obtain mixture A; wherein, the specific parameters of the ball-milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0085] Step Four: Use a tablet press to press mixture A, set the pressure to 20 MPa, hold the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0086] Step Five: Heat mixture B in a nitrogen atmosphere to 500 °C at a heating rate of 5 °C / min and hold for 3 h, then naturally cool to room temperature and grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material.

[0087] In this comparative example, when preparing the modified bentonite, sodium citrate was not used, and the remaining steps were the same as those in Example 1.

[0088] Comparative Example 4

[0089] A preparation method of a bentonite-based composite adsorbent material, comprising the following steps:

[0090] Step One: Prepare modified bentonite:

[0091] S11. Dissolve natural calcium-based bentonite in deionized water, purify it, dry it at 80 °C, grind it through a 100-mesh sieve to obtain bentonite powder;

[0092] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stir at 60 °C for 10 h, then filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain pretreated bentonite;

[0093] S13. Add pretreated bentonite to deionized water according to the mass-volume ratio of 1 g:10 mL, disperse it evenly, then add sodium citrate, stir at 60 °C for 1 h, add 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let it stand at room temperature for 24 h, filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain modified bentonite; among them, the mass ratio of pretreated bentonite, sodium citrate, and cetyltrimethylammonium bromide is 1:0.4:0.5;

[0094] Step Two. Prepare modified biochar:

[0095] S21. Grind corn straw through a 100-mesh sieve, add it to deionized water, dropwise add sodium hypochlorite while stirring at 40 °C. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 100-mesh sieve to obtain modified straw powder; among them, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0096] S22. Grind and mix modified straw powder and pseudoboehmite evenly according to the mass ratio of 3:1. Under a nitrogen atmosphere, heat it to 800 °C at a heating rate of 5 °C / min and hold for 2 h, then naturally cool to room temperature, and grind through a 100-mesh sieve to obtain modified biochar;

[0097] Step Three. Mix modified bentonite and modified biochar according to the mass ratio of 7:3, and ball mill for 1 h to obtain mixture A; among them, the specific parameters of ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0098] Step Four. Use a tablet press to press mixture A, set the pressure to 20 MPa, keep the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0099] Step Five. Under a nitrogen atmosphere, heat mixture B to 500 °C at a heating rate of 5 °C / min and hold for 3 h, then naturally cool to room temperature, and grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material of this comparative example. When preparing modified bentonite, polyvinylpyrrolidone was not used, and the other steps are the same as those in Example 1.

[0100] Comparative Example 5

[0101] A preparation method of a bentonite-based composite adsorbent, comprising the following steps:

[0102] Step 1: Prepare modified bentonite:

[0103] S11. Dissolve natural calcium-based bentonite in deionized water, dry it at 80 °C after purification, grind it through a 100-mesh sieve to obtain bentonite powder;

[0104] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stir at 60 °C for 10 h, then filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain pretreated bentonite;

[0105] S13. Add the pretreated bentonite to deionized water according to the mass-volume ratio of 1 g:10 mL, disperse it evenly, then add sodium citrate and polyvinylpyrrolidone, stir at 60 °C for 1 h, then add a 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let it stand at room temperature for 24 h, filter, wash, dry at 80 °C, and grind through a 100-mesh sieve to obtain modified bentonite; wherein, the mass ratio of the pretreated bentonite, sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0106] Step 2: Ball-mill the modified bentonite for 1 h to obtain mixture A; wherein, the specific parameters of the ball-milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0107] Step 3: Use a tablet press to press mixture A, set the pressure to 20 MPa, keep the pressure for 2 min, grind through a 200-mesh sieve to obtain mixture B;

[0108] Step 4: Heat mixture B in a nitrogen atmosphere at a heating rate of 5 °C / min to 500 °C and hold for 3 h, then naturally cool to room temperature, grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent. In this comparative example, modified biomass carbon is not added, only modified bentonite is used, and the remaining steps are the same as those in Example 1.

[0109] Comparative Example 6

[0110] A preparation method of a bentonite-based composite adsorbent, comprising the following steps:

[0111] Step 1: Prepare modified bentonite:

[0112] S11. Dissolve natural calcium-based bentonite in deionized water, dry it at 80 °C after purification, grind it through a 100-mesh sieve to obtain bentonite powder;

[0113] S12. Add 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution. After stirring at 60 °C for 10 h, perform suction filtration, washing, drying at 80 °C, and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0114] S13. Add the pretreated bentonite to deionized water at a mass-to-volume ratio of 1 g:10 mL, disperse evenly, then add sodium citrate and polyvinylpyrrolidone, stir at 60 °C for 1 h, add a 5 wt% cetyltrimethylammonium bromide solution, stir at 80 °C for 2 h, let stand at room temperature for 24 h, perform suction filtration, washing, drying at 80 °C, and grinding through a 100-mesh sieve to obtain modified bentonite; among them, the mass ratio of the pretreated bentonite, sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0115] Step Two. Prepare modified biochar:

[0116] S21. Grind corn straw through a 100-mesh sieve, add it to deionized water, and dropwise add sodium hypochlorite while stirring at 40 °C. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 100-mesh sieve to obtain modified straw powder; among them, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0117] S22. Grind and mix the modified straw powder and pseudoboehmite evenly at a mass ratio of 3:1. Under a nitrogen atmosphere, heat to 800 °C at a heating rate of 5 °C / min and hold for 2 h, then naturally cool to room temperature and grind through a 100-mesh sieve to obtain modified biochar;

[0118] Step Three. Mix the modified bentonite and modified biochar at a mass ratio of 7:3 and ball mill for 1 h to obtain mixture A; among them, the specific parameters of the ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0119] Step Four. Under a nitrogen atmosphere, heat mixture A to 500 °C at a heating rate of 5 °C / min and hold for 3 h, then naturally cool to room temperature and grind through a 200-mesh sieve to obtain the bentonite-based composite adsorbent material.

[0120] In this comparative example, no pressure pressing is performed, and the remaining steps are the same as those in Example 1.

[0121] Comparative Example 7

[0122] A preparation method of a bentonite-based composite adsorbent material, comprising the following steps:

[0123] Step One. Prepare biochar:

[0124] S21. Grind the corn straw through a 100-mesh sieve, add it to deionized water, and while stirring at 40 °C, dropwise add sodium hypochlorite. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 3 with a 5 wt% hydrochloric acid aqueous solution, centrifuge, wash, dry, grind through a 100-mesh sieve to obtain modified straw powder; wherein, the mass ratio of corn straw, deionized water, and sodium hypochlorite is 1:10:0.2;

[0125] S22. Under a nitrogen atmosphere, heat the modified straw powder at a heating rate of 5 °C / min to 800 °C and hold for 2 h, then naturally cool to room temperature, grind through a 100-mesh sieve to obtain biochar;

[0126] Step 2. Mix natural calcium-based bentonite and biochar in a mass ratio of 7:3, and ball mill for 1 h to obtain mixture A; wherein, the specific parameters of the ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 10:1, and the rotation speed is 300 rpm;

[0127] Step 3. Use a tablet press to press mixture A, set the pressure to 20 MPa, hold the pressure for 2 min, grind through a 200-mesh sieve to obtain mixture B;

[0128] Step 4. Under a nitrogen atmosphere, heat mixture B at a heating rate of 5 °C / min to 500 °C and hold for 3 h, then naturally cool to room temperature, grind through a 200-mesh sieve to obtain a bentonite-based composite adsorbent material.

[0129] In this comparative example, unmodified bentonite and unmodified biochar are used, and the remaining steps are the same as those in Example 1.

[0130] Wastewater treatment experiment:

[0131] Take 0.5 g of the bentonite-based composite adsorbent material (or bentonite-based composite membrane), add it to 200 mL of a 100 mg / L Pb 2+ aqueous solution, and perform oscillatory adsorption at 200 rpm in a constant temperature shaker at 25 °C for 1 h, then separate the solid and liquid, and use an inductively coupled plasma spectrometer to detect the concentration of Pb 2+ in the solution;

[0132] Take 0.5 g of the bentonite-based composite adsorbent material (or bentonite-based composite membrane), add it to 200 mL of a 50 mg / L phenol aqueous solution, and perform oscillatory adsorption at 200 rpm in a constant temperature shaker at 25 °C for 1 h, then separate the solid and liquid, and use 4-aminoantipyrine spectrophotometry to determine the phenol concentration in the solution;

[0133] Calculate the removal rate according to the following formula:

[0134] Removal rate = (C 0 - C) / C 0 × 100%

[0135] In the formula, C 0 represents the initial concentration of Pb 2+ (phenol) (mg / L), and C represents the concentration of Pb 2+ (phenol) after adsorption (mg / L).

[0136] In Examples 1-2 and Comparative Examples 1-7, the removal rates of Pb 2+ and phenol are shown in Table 1. It can be seen that the bentonite-based composite adsorbent prepared in Example 1 has excellent adsorption capacity for both heavy metal ions and organic pollutants in sewage; in Example 2, the bentonite-based composite membrane prepared from the bentonite-based composite adsorbent has improved adsorption capacity for both Pb 2+ and phenol, and is easier to separate and recover after adsorption.

[0137] Table 1

[0138]

[0139]

[0140] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing a bentonite-based composite adsorption material, characterized in that: The following steps are involved: Step 1, preparing modified bentonite; Step 2: preparing modified biochar; Step 3, mixing the modified bentonite and the modified biochar, and ball milling to obtain a mixture A; Step 4: Using a tablet press to press the mixture A under pressure, grind it, and obtain a mixture B; Step 5: heat-treating the mixture B under a nitrogen atmosphere, naturally cooling it to room temperature, and grinding it to obtain a bentonite-based composite adsorption material.

2. The method for preparing a bentonite-based composite adsorption material according to claim 1, characterized in that: The preparation method of the modified bentonite comprises the following steps: S11, dissolving bentonite in deionized water, drying after purification, and grinding through a 50-200 mesh sieve to obtain bentonite powder; S12, adding bentonite powder into a hydrochloric acid aqueous solution, stirring at a constant temperature, filtering, washing, drying, and grinding to obtain pretreated bentonite; S13, the pretreated bentonite is added into deionized water and dispersed evenly, then sodium citrate and polyvinyl pyrrolidone are added, stirred at a constant temperature, and then cetyl trimethyl ammonium bromide solution is added, stirring is continued, and the mixture is allowed to stand at room temperature, filtered, washed, dried, and ground to obtain modified bentonite.

3. The method for preparing a bentonite-based composite adsorption material according to claim 1, characterized in that: The method for preparing the modified biochar comprises the following steps: S21, grinding corn stalks, adding them to deionized water, heating, adding sodium hypochlorite dropwise while stirring, continuing to stir after the addition is complete, cooling to room temperature, adjusting the pH with aqueous hydrochloric acid, centrifuging, washing, drying, and grinding to obtain modified stalk powder; S22, the modified straw powder and pseudo-boehmite are ground and mixed evenly, pyrolyzed in a nitrogen atmosphere, naturally cooled to room temperature, and ground to obtain modified biochar.

4. The method for preparing a bentonite-based composite adsorption material according to claim 2, characterized in that: In S12, the mass volume ratio of bentonite powder to hydrochloric acid aqueous solution is 1g:5-10mL; the concentration of hydrochloric acid aqueous solution is 1-10wt%; the temperature of constant temperature stirring is 50-70°C, and the time is 8-12h; and the powder is ground through a 50-200 mesh sieve.

5. The method for preparing a bentonite-based composite adsorption material according to claim 2, characterized in that: In the S13, the mass volume ratio of the pretreated bentonite and deionized water is 1g:5-20mL; the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone and hexadecyltrimethylammonium bromide is 1:0.2-0.6:0.1-0.5:0.3-0.6; the concentration of the hexadecyltrimethylammonium bromide solution is 1-10wt%; the constant temperature stirring temperature is 50-70°C, the time is 0.5-2h; the temperature of continued stirring is 70-90°C, the time is 1-3h; standing at room temperature for 12-36h; grinding through a 50-200 mesh sieve.

6. The method for preparing a bentonite-based composite adsorption material according to claim 3, characterized in that: In the S21, the mass ratio of corn stalks, deionized water and sodium hypochlorite is 1:5-15:0.1-0.5; the temperature is raised to 30-50°C; after the dropwise addition is completed, stirring is continued for 20-40 minutes; the concentration of the hydrochloric acid aqueous solution is 1-10wt%, and the pH is adjusted to 2-4; and the mixture is ground through a 50-200 mesh sieve; In the S22, the mass ratio of modified straw powder to pseudo-boehmite is 3:0.5-1.5; the pyrolysis temperature is 700-900°C, and the time is 1-3h; Grind through 50-200 mesh sieve.

7. The method for preparing a bentonite-based composite adsorption material according to claim 1, characterized in that: In the step 3, the mass ratio of modified bentonite to modified biochar is 7:2-4; the specific parameters of ball milling are: the grinding balls are zirconia balls, the ball-to-material ratio is 5-15:1, the rotation speed is 200-400 rpm, and the time is 1-2 hours; In the step 4, the specific method of holding pressure and pressing is: using a tablet press for pressing, the pressure of the tablet press is 10-40 MPa, and the holding time is 2-5 min; grinding through a 50-200 mesh sieve; In the step 5, the specific method of heat treatment is: heating to 400-600° C. at a heating rate of 3-8° C. / min and keeping the temperature for 2-4 hours; grinding through a 50-200 mesh sieve.

8. Use of the bentonite-based composite adsorbent material prepared by the preparation method according to claim 1 in sewage treatment, characterized in that: The bentonite-based composite adsorption material is used for adsorbing heavy metal ions and organic pollutants.

9. Use of the bentonite-based composite adsorbent material prepared by the preparation method according to claim 1 in sewage treatment, characterized in that: The bentonite-based composite adsorption material is used to prepare a bentonite-based composite membrane, and the bentonite-based composite membrane is used to adsorb heavy metal ions and organic pollutants.

10. The use according to claim 9, characterized in that The method for preparing the bentonite-based composite membrane comprises the following steps: Step 1, taking polyimine ether imine ketone and polyvinyl alcohol in a mass ratio of 4 to 8:1, adding them to dimethyl sulfoxide, stirring them in a water bath at a constant temperature of 70 to 90° C. for 1 to 3 hours, and obtaining a mixed solution with a polyimine ether imine ketone concentration of 5 to 15 wt %; Step 2, grinding the bentonite-based composite adsorption material through a 1000 mesh sieve, then adding it to the mixed solution, stirring it in a water bath at a constant temperature of 50 to 70° C. for 2 to 4 hours, and then ultrasonicating it for 1 to 2 hours to obtain a casting solution; wherein the mass ratio of the bentonite-based composite adsorption material to the polyimine ether imine ketone in step 1 is 1 to 3:5; Step 3: pour the casting solution onto a glass plate, prepare a film by solution casting, and dry it to obtain a bentonite-based composite membrane.

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