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

Abstract

The present invention discloses the preparation of a bentonite-based composite adsorption material and its application in sewage treatment, comprising: preparing modified bentonite; preparing modified biochar; mixing the modified bentonite and modified biochar, and ball milling to obtain a mixture A; pressing the mixture A under pressure using a tablet press, and grinding to obtain a mixture B; heat-treating the mixture B under a nitrogen atmosphere, naturally cooling it to room temperature, and grinding to obtain a bentonite-based composite adsorption material. The bentonite-based composite adsorption material is used to adsorb heavy metal ions and organic pollutants in sewage. The bentonite-based composite adsorption material prepared by the present invention has excellent adsorption capacity for both heavy metal ions and organic pollutants in sewage.

Description

Technical Field

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

[0002] With rapid economic development, water pollution is becoming increasingly severe, posing a serious threat to human health and sustainable development. Wastewater treatment methods can be categorized into three types: physical, biological, and chemical. Physical adsorption, among others, removes pollutants from wastewater through the interaction between adsorbent materials and pollutants. It is widely used due to its simplicity, high removal efficiency, and low cost. Its adsorption effectiveness depends primarily on the selected adsorbent material. Currently, the main adsorbent materials used in wastewater treatment include activated carbon, diatomaceous earth, bentonite, resins, and nanomaterials.

[0003] Bentonite, a clay mineral primarily composed of montmorillonite, is widely used in industry, agriculture, and environmental protection due to its unique physical and chemical properties. Bentonite is non-toxic, highly absorbent, adsorbent, and ion-exchangeable, and it is inexpensive. It can be used in wastewater treatment to adsorb heavy metals and organic pollutants. However, in practice, bentonite's adsorption capacity is limited. Therefore, developing a new bentonite-based composite adsorbent material to enhance its adsorption capacity is of great significance for water pollution treatment. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these objects and other advantages of the present invention, a method for preparing a bentonite-based composite adsorption material is provided, comprising the following steps:

[0006] Step 1, preparing modified bentonite;

[0007] Step 2: preparing modified biochar;

[0008] Step 3: mixing the modified bentonite and the modified biochar, and ball milling to obtain a mixture A;

[0009] Step 4: Using a tablet press, compressing and grinding the mixture A to obtain a mixture B;

[0010] 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.

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

[0012] S11, dissolving bentonite in deionized water, drying after purification, and grinding through a 50-200 mesh sieve to obtain bentonite powder;

[0013] S12, adding bentonite powder to a hydrochloric acid aqueous solution, stirring at a constant temperature, filtering, washing, drying, and grinding to obtain pretreated bentonite;

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

[0015] Preferably, the method for preparing the modified biochar comprises the following steps:

[0016] S21, grinding corn stalks, adding them to deionized water, heating, adding sodium hypochlorite dropwise with 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;

[0017] S22, the modified straw powder and pseudo-boehmite are ground and mixed evenly, pyrolyzed under a nitrogen atmosphere, naturally cooled to room temperature, and ground to obtain modified biochar.

[0018] Preferably, 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.

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

[0020] Preferably, in 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.

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

[0022] Preferably, in step three, the mass ratio of modified bentonite to modified biochar is 7:2-4; the specific parameters of ball milling are: 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.

[0023] Preferably, in step 4, the specific method of maintaining pressure and pressing is: using a tablet press for pressing, the pressure of the tablet press is 10-40 MPa, and the pressure holding time is 2-5 minutes; grinding through a 50-200 mesh sieve.

[0024] Preferably, in step five, 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.

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

[0026] A bentonite-based composite adsorption material prepared by the preparation method described above is used in sewage treatment. 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.

[0027] Preferably, the method for preparing the bentonite-based composite membrane comprises the following steps:

[0028] Step 1, taking polyimine ether imine ketone and polyvinyl alcohol in a mass ratio of 4 to 8:1, adding them to dimethyl sulfoxide, and stirring them in a water bath at a constant temperature of 70 to 90° C. for 1 to 3 hours to obtain a mixed solution with a polyimine ether imine ketone concentration of 5 to 15 wt%;

[0029] Step 2: Grind the bentonite-based composite adsorption material through a 1000-mesh sieve, then add the material to the mixed solution, stir in a water bath at a constant temperature of 50-70° C. for 2-4 hours, and then ultrasonicate for 1-2 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 1-3:5;

[0030] 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.

[0031] The present invention includes at least the following beneficial effects: The present invention provides a preparation method of a bentonite-based composite adsorption material, first, the bentonite is modified, the bentonite is purified, impurities are removed, and the bentonite is added to an acidic solution for treatment to improve the surface roughness of the bentonite, increase its specific surface area and active sites, and then treated with sodium citrate, polyvinyl pyrrolidone and hexadecyltrimethylammonium bromide to improve its dispersibility and stability, introduce rich functional groups, and effectively enhance its adsorption capacity and reaction activity; then, the biochar is modified to improve its dispersibility, adsorption capacity and reaction activity; finally, the modified bentonite and modified biochar are compounded, ball milled, pressure-maintained pressed and heat treated to form a uniform, stable and tight adsorption network structure, and the obtained bentonite-based composite adsorption material has excellent adsorption capacity for heavy metal ions and organic pollutants in sewage. In addition, the bentonite-based composite membrane prepared by the present invention using the bentonite-based composite adsorption material has a further improved adsorption capacity for heavy metal ions and organic pollutants in sewage, and after the adsorption is completed, the composite membrane is easier to separate and recover than the powder adsorption material.

[0032] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0033] The present invention is described in further detail below so that those skilled in the art can implement the invention with reference to the description.

[0034] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0035] Example 1

[0036] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0037] Step 1: Preparation of modified bentonite:

[0038] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

[0039] S12, adding 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stirring at 60° C. for 10 h, filtering, washing, drying at 80° C., and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0040] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture evenly, then adding sodium citrate and polyvinyl pyrrolidone, stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution, stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0041] Step 2: Preparation of modified biochar:

[0042] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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;

[0043] S22, the modified straw powder and pseudo-boehmite were ground and mixed uniformly in a mass ratio of 3:1, and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0044] Step 3: The modified bentonite and the modified biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0045] Step 4: Compress mixture A using a tablet press at a set pressure of 20 MPa, maintain the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0046] Step 5: The mixture B was heated to 500° C. at a heating rate of 5° C. / min in a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

[0047] Example 2

[0048] A method for preparing a bentonite-based composite membrane comprises the following steps:

[0049] Step 1: polyimine ether imine ketone and polyvinyl alcohol are taken in a mass ratio of 5:1, added to dimethyl sulfoxide, and stirred in a water bath at 80° C. for 2 hours to obtain a mixed solution with a polyimine ether imine ketone concentration of 10 wt%;

[0050] Step 2: Grind the bentonite-based composite adsorption material prepared in Example 1 through a 1000-mesh sieve, add the mixture to the mixed solution, stir in a 60°C water bath for 3 hours, and then ultrasonicate at 300W and 60kHz for 1 hour 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 2:5;

[0051] Step 3: pouring the casting solution onto a smooth glass plate, preparing a film by solution casting, and drying at 60° C. to obtain a bentonite-based composite membrane with a thickness of 180 μm;

[0052] Among them, the polyimine ether imine ketone is prepared according to the Chinese patent CN118681423A: a clean single-necked bottle is taken, a magnetic stirrer is placed and sealed, the bottle is vacuumed under heating, and high-purity nitrogen is filled after cooling, and the cycle is repeated three times to remove impurity gases; under nitrogen protection, reactants 4,4'-dibromobenzophenone, 4,4'-diaminodiphenyl ether, catalyst Pd2(dba)3, sodium tert-butoxide, 1,1'-binaphthyl-2,2'-diphenylphosphine and N,N'-dimethylacetamide are added to the bottle in a molar volume ratio of 1mmol:1mmol:0.01mmol:2.8mmol:0.03mmol:2mL. , stir evenly, heat to 100°C, keep warm for 4 hours, then heat to 160°C, keep warm for 24 hours, and naturally cool to room temperature; add the liquid substance in the bottle dropwise into distilled water to induce solid precipitation, filter and collect the precipitate, and then repeatedly wash the precipitate with distilled water to fully wash away the residual solvent and other impurities; redissolve the washed precipitate in N,N'-dimethylacetamide, filter, and add the filtrate dropwise into methanol to induce secondary precipitation of the solid, repeat the above dissolution-precipitation process three times to ensure high purification of the product, and filter after each precipitation; finally, the obtained precipitate is vacuum dried at 80°C to obtain a light yellow powder, which is polyiminoetheriminoketone.

[0053] Comparative Example 1

[0054] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0055] Step 1: Preparation of modified biochar:

[0056] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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 pseudo-boehmite were ground and mixed uniformly in a mass ratio of 3:1, and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0058] Step 2: Natural calcium-based bentonite and modified biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0059] Step 3: Compress mixture A using a tablet press at a set pressure of 20 MPa for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0060] Step 4: The mixture B was heated to 500° C. at a heating rate of 5° C. / min in a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

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

[0062] Comparative Example 2

[0063] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0064] Step 1: Preparation of modified bentonite:

[0065] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

[0066] S12, adding 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stirring at 60° C. for 10 h, filtering, washing, drying at 80° C., and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0067] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture evenly, then adding sodium citrate and polyvinyl pyrrolidone, stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution, stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0068] Step 2: Preparation of biochar:

[0069] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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, heating the modified straw powder to 800° C. at a heating rate of 5° C. / min under a nitrogen atmosphere and keeping the temperature for 2 h, naturally cooling to room temperature, and grinding the powder through a 100-mesh sieve to obtain biochar;

[0071] Step 3: The modified bentonite and biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 hour to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0072] Step 4: Compress mixture A using a tablet press at a set pressure of 20 MPa, maintain the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0073] Step 5: The mixture B was heated to 500° C. at a heating rate of 5° C. / min in a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

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

[0075] Comparative Example 3

[0076] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0077] Step 1: Preparation of modified bentonite:

[0078] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

[0079] S12, adding 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stirring at 60° C. for 10 h, filtering, washing, drying at 80° C., and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0080] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture uniformly, then adding polyvinyl pyrrolidone and stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution and stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, polyvinyl pyrrolidone, and cetyltrimethylammonium bromide is 1:0.2:0.5;

[0081] Step 2: Preparation of modified biochar:

[0082] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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, the modified straw powder and pseudo-boehmite were ground and mixed uniformly in a mass ratio of 3:1, and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0084] Step 3: The modified bentonite and the modified biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0085] Step 4: Compress mixture A using a tablet press at a set pressure of 20 MPa, maintain the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0086] Step 5: The mixture B was heated to 500° C. at a heating rate of 5° C. / min in a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

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

[0088] Comparative Example 4

[0089] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0090] Step 1: Preparation of modified bentonite:

[0091] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

[0092] S12, adding 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stirring at 60° C. for 10 h, filtering, washing, drying at 80° C., and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0093] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture evenly, then adding sodium citrate, stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution, stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, sodium citrate, and cetyltrimethylammonium bromide is 1:0.4:0.5;

[0094] Step 2: Preparation of modified biochar:

[0095] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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;

[0096] S22, the modified straw powder and pseudo-boehmite were ground and mixed uniformly in a mass ratio of 3:1, and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0097] Step 3: The modified bentonite and the modified biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0098] Step 4: Compress mixture A using a tablet press at a set pressure of 20 MPa, maintain the pressure for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0099] Step 5. The mixture B was heated to 500°C in a nitrogen atmosphere at a heating rate of 5°C / min and kept warm for 3 h, naturally cooled to room temperature, and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material. In this comparative example, polyvinyl pyrrolidone was not used when preparing the modified bentonite, and the remaining steps were the same as in Example 1.

[0100] Comparative Example 5

[0101] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0102] Step 1: Preparation of modified bentonite:

[0103] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

[0104] S12, adding 100 g of bentonite powder to 800 mL of 5 wt% hydrochloric acid aqueous solution, stirring at 60° C. for 10 h, filtering, washing, drying at 80° C., and grinding through a 100-mesh sieve to obtain pretreated bentonite;

[0105] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture evenly, then adding sodium citrate and polyvinyl pyrrolidone, stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution, stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0106] Step 2: ball milling the modified bentonite for 1 hour to obtain a 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: Compress mixture A using a tablet press at a set pressure of 20 MPa for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0108] Step 4: The mixture B was heated to 500°C in a nitrogen atmosphere at a heating rate of 5°C / min and kept warm for 3 h, naturally cooled to room temperature, and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material. In this comparative example, no modified biochar was added, only modified bentonite was used, and the remaining steps were the same as in Example 1.

[0109] Comparative Example 6

[0110] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0111] Step 1: Preparation of modified bentonite:

[0112] S11, dissolving natural calcium-based bentonite in deionized water, drying at 80° C. after purification, and grinding through a 100-mesh sieve to obtain bentonite powder;

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

[0114] S13, adding the pretreated bentonite to deionized water at a mass volume ratio of 1 g:10 mL and dispersing the mixture evenly, then adding sodium citrate and polyvinyl pyrrolidone, stirring at 60° C. for 1 h, adding 5 wt % cetyltrimethylammonium bromide solution, stirring at 80° C. for 2 h, standing at room temperature for 24 h, filtering, washing, drying at 80° C., and grinding through a 100 mesh sieve to obtain modified bentonite; wherein the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone, and cetyltrimethylammonium bromide is 1:0.4:0.2:0.5;

[0115] Step 2: Preparation of modified biochar:

[0116] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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;

[0117] S22, the modified straw powder and pseudo-boehmite were ground and mixed uniformly in a mass ratio of 3:1, and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and kept at this temperature for 2 h, and then naturally cooled to room temperature, and ground through a 100-mesh sieve to obtain modified biochar;

[0118] Step 3: The modified bentonite and the modified biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0119] Step 4: The mixture A was heated to 500° C. at a heating rate of 5° C. / min under a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

[0120] In this comparative example, no pressure-maintaining pressing was performed, and the remaining steps were the same as those in Example 1.

[0121] Comparative Example 7

[0122] A method for preparing a bentonite-based composite adsorption material comprises the following steps:

[0123] Step 1: Preparation of biochar:

[0124] S21, grinding corn straw through a 100-mesh sieve, adding deionized water, adding sodium hypochlorite dropwise at 40° C. with stirring, stirring for 30 minutes after the addition is complete, cooling to room temperature, adjusting the pH to 3 with a 5 wt % hydrochloric acid aqueous solution, centrifuging, washing, drying, and grinding 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, heating the modified straw powder to 800° C. at a heating rate of 5° C. / min under a nitrogen atmosphere and keeping the temperature for 2 h, naturally cooling to room temperature, and grinding the powder through a 100-mesh sieve to obtain biochar;

[0126] Step 2: Natural calcium-based bentonite and biochar were mixed in a mass ratio of 7:3 and ball-milled for 1 h to obtain a mixture A; wherein the specific parameters of the ball milling were: zirconia balls, a ball-to-material ratio of 10:1, and a rotation speed of 300 rpm;

[0127] Step 3: Compress mixture A using a tablet press at a set pressure of 20 MPa for 2 min, and grind through a 200-mesh sieve to obtain mixture B;

[0128] Step 4: The mixture B was heated to 500° C. at a heating rate of 5° C. / min in a nitrogen atmosphere and kept at this temperature for 3 h, then naturally cooled to room temperature and ground through a 200-mesh sieve to obtain a bentonite-based composite adsorption material.

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

[0130] Sewage treatment experiment:

[0131] Take 0.5g bentonite-based composite adsorption material (or bentonite-based composite membrane), add 200mL 100mg / L Pb 2+ The aqueous solution was shaken at 200 rpm in a constant temperature shaker at 25 ° C for 1 h, and the solid-liquid separation was performed. The Pb content in the solution was detected by inductively coupled plasma spectrometer. 2+ concentration;

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

[0133] The removal rate was calculated according to the following formula:

[0134] Removal rate = (C0-C) / C0×100%

[0135] Where C0 represents Pb 2+ (phenol) initial concentration (mg / L), C represents the Pb after adsorption 2+ (Phenol) concentration (mg / L).

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

[0137] Table 1

[0138]

[0139]

[0140] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and 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, comprising 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 to a hydrochloric acid aqueous solution, stirring at a constant temperature, filtering, washing, drying, and grinding to obtain pretreated bentonite; S13, adding the pretreated bentonite to deionized water and dispersing it evenly, then adding sodium citrate and polyvinyl pyrrolidone, stirring at a constant temperature, then adding cetyltrimethylammonium bromide solution, continuing stirring, standing at room temperature, filtering, washing, drying, and grinding to obtain modified bentonite; Step 2: preparing modified biochar, comprising the following steps: S21, grinding corn stalks, adding them to deionized water, heating, adding sodium hypochlorite dropwise with 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, grinding and mixing the modified straw powder and pseudo-boehmite, pyrolyzing the mixture under a nitrogen atmosphere, naturally cooling the mixture to room temperature, and grinding the mixture to obtain 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, compressing and grinding the mixture A to 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, wherein: In the 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.

3. The method for preparing a bentonite-based composite adsorption material according to claim 1, wherein: In S13, the mass volume ratio of the pretreated bentonite and deionized water is 1 g:5-20 mL; the mass ratio of the pretreated bentonite, sodium citrate, polyvinyl pyrrolidone 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 constant temperature stirring temperature is 50-70° C. for 0.5-2 h; the stirring temperature is continued at 70-90° C. for 1-3 h; the mixture is allowed to stand at room temperature for 12-36 h; and the mixture is ground through a 50-200 mesh sieve.

4. The method for preparing a bentonite-based composite adsorption material according to claim 1, wherein: Said S21, the mass ratio of corn straw, deionized water and sodium hypochlorite is 1: 5 ~ 15: 0.1 ~ 0.5; heated to 30 ~ 50 ℃; after the addition is complete, stirring is continued for 20 ~ 40min; the concentration of aqueous hydrochloric acid is 1 ~ 10wt%, adjusting the pH to 2 ~ 4; grinding through a 50 ~ 200 mesh sieve; In said 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 1-3 hours; Grind through 50~200 mesh sieve.

5. The method for preparing a bentonite-based composite adsorption material according to claim 1, wherein: In step 3, the mass ratio of modified bentonite to modified biochar is 7:2-4; the specific parameters of ball milling are: 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 pressure holding and pressing is: using a tablet press for pressing, the pressure of the tablet press is 10-40 MPa, and the pressure holding time is 2-5 min; grinding through a 50-200 mesh sieve; In 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; Grind through 50~200 mesh sieve.

6. Use of the bentonite-based composite adsorption 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.

7. Use of the bentonite-based composite adsorption 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.

8. The use according to claim 7, 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 4-8:1, adding them to dimethyl sulfoxide, and stirring them in a water bath at a constant temperature of 70-90° C. for 1-3 hours to obtain a mixed solution with a polyimine ether imine ketone concentration of 5-15wt%; Step 2: Grind the bentonite-based composite adsorption material through a 1000-mesh sieve, then add the material to the mixed solution, stir in a water bath at a constant temperature of 50-70° C. for 2-4 hours, and then ultrasonicate for 1-2 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 1-3:5; 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.

Images