Attapulgite composite material for wastewater treatment and preparation method thereof

Abstract

The invention provides an attapulgite composite material for wastewater treatment and a preparation method thereof, and the preparation method of the attapulgite composite material for wastewater treatment comprises the following steps: (1) preparing a chitosan-loaded titanium dioxide composite material; (2) preparing a chitosan composite flocculant; and (3) mixing the chitosan-loaded titanium dioxide composite material, a coagulant aid and a chitosan composite flocculant to prepare the attapulgite composite material for wastewater treatment. The attapulgite composite material for wastewater treatment has high chromium ion adsorption capacity, high mercury ion adsorption capacity and high Congo red dye adsorption capacity, even if the temperature is reduced, the chromium ion adsorption capacity, the mercury ion adsorption capacity and the Congo red dye adsorption capacity are not obviously reduced, and the adsorption capacity of heavy metal ions and dyes is high; and the raw materials for preparing the attapulgite composite material for wastewater treatment are simple and easy to obtain, so that the cost for preparing the attapulgite composite material for wastewater treatment is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a composite material of attapulgite for wastewater treatment and a preparation method thereof. BACKGROUND

[0002] Attapulgite, as a natural mineral, has good adsorption and ion exchange capacity, which shows great potential in treating heavy metals, dyes and other organic pollutants. By compounding with other materials, its application performance in wastewater treatment can be further enhanced.

[0003] Attapulgite composite material is an environmentally friendly material that combines natural clay minerals with other materials. Its basic composition includes natural attapulgite and one or more functional additives such as coagulants. This composite material not only retains the physical and chemical properties of attapulgite itself, such as high specific surface area, good adsorption performance and ion exchange capacity, but also significantly improves the wastewater treatment performance of the composite material by introducing new components. For example, CN108212108A discloses a kind of attapulgite composite adsorption material and preparation method, however, the scheme of CN108212108A still faces a series of challenges and limitations in practical application, for example, the adsorption characteristics of attapulgite composite material are closely related to environmental conditions such as temperature, and the adsorption capacity is low at low temperature such as winter, and the separation efficiency of heavy metals, dyes and other organic pollutants in wastewater is low.

[0004] Magnetic chitosan can be used to remove Cu 2+ , Cr 2+ , Hg 2+ , Zn 2+ , Pb 2+ , Ca 2+ , Ag + and other metal ions in water, and can also be used to treat organic wastewater and quickly reach equilibrium. The combination of magnetic chitosan and attapulgite helps to improve the adsorption capacity of organic pollutants. For example, CN 111871386 A discloses a modified attapulgite rod soil composite sewage treatment agent and its preparation and application, but similarly, the adsorption effect of this material is greatly affected by temperature. SUMMARY

[0005] The present application aims to provide a composite material of attapulgite for wastewater treatment and a preparation method thereof, to solve the problem of how to reduce the use cost and have high adsorption capacity at low temperature.

[0006] The present application provides a preparation method of a composite material of attapulgite for wastewater treatment, comprising the following steps:

[0007] (1) Preparation of chitosan@titanium dioxide composite material loaded;

[0008] (2) Preparation of chitosan composite flocculant;

[0009] (3) The loaded chitosan@titanium dioxide composite material, the coagulant aid and the chitosan composite flocculant are mixed to prepare the attapulgite composite material for wastewater treatment.

[0010] In some embodiments of the present application, the mass ratio of the loaded chitosan@titanium dioxide composite material and the chitosan composite flocculant is 1:0.4-0.7.

[0011] In some embodiments of the present application, the mass ratio of the loaded chitosan@titanium dioxide composite material and the chitosan composite flocculant can be 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75 or a numerical range between any two of them, optionally the mass ratio of the loaded chitosan@titanium dioxide composite material and the chitosan composite flocculant is 1:0.4-0.6, further optionally, the mass ratio of the loaded chitosan@titanium dioxide composite material and the chitosan composite flocculant is 1:0.4-0.5.

[0012] In some embodiments of the present application, the stirring speed during mixing of the loaded chitosan@titanium dioxide composite material, the coagulant aid and the chitosan composite flocculant is 90-110 r / min.

[0013] In some embodiments of the present application, the raw materials for preparing the chitosan composite flocculant include iron-containing magnetic nano-ions, sodium silicate, aluminum sulfate, zinc sulfate and chitosan.

[0014] In some embodiments of the present application, in the raw materials for preparing the chitosan composite flocculant, the mass ratio of the iron-containing magnetic nano-ions and the sodium silicate is 1:1.7-1.8; the element molar ratio of the aluminum sulfate, the zinc sulfate and the sodium silicate is n(Al):n(Zn):n(Si) = 9.2-9.4:3-3.1:1, and the mass ratio of the chitosan and the sodium silicate is 1:3.0-3.3.

[0015] In some embodiments of the present application, the aluminum sulfate is aluminum sulfate octadecahydrate, and the zinc sulfate is zinc sulfate heptahydrate.

[0016] In some embodiments of the present application, the preparation method of the chitosan composite flocculant comprises the following steps:

[0017] Step 1: After preparing a solution containing iron-containing magnetic nano-ions, sodium silicate is added, and the pH is adjusted to 1-3, followed by stirring and aging to prepare a pretreatment liquid;

[0018] Step 2: After mixing the aluminum sulfate solution, the zinc sulfate solution and the pretreated chitosan solution, the pretreatment liquid is added, and post-treatment is performed to prepare the chitosan composite flocculant.

[0019] In some embodiments of the present application, the preparation method of the chitosan composite flocculant, in step 1, the stirring temperature is 40-45℃, and the duration is 2-3 hours; in step 2, after adding the pretreatment solution, stirring at 40-45℃ is carried out for 2-3 hours, and then post-treatment is carried out.

[0020] In some embodiments of the present application, the preparation method of the chitosan composite flocculant, the post-treatment involved in step 2 includes but is not limited to stirring and ripening.

[0021] In some embodiments of the present application, the preparation method of the iron-containing magnetic nano-ion includes the following steps:

[0022] Step 1: dissolve ferric chloride hexahydrate in an acid solution;

[0023] Step 2: dissolve ferrous chloride tetrahydrate in an acid solution, and then add iron powder;

[0024] Step 3: mix the substances of step 1 and step 2, add a basic substance, and post-treat to obtain the iron-containing magnetic nano-ion.

[0025] In some embodiments of the present application, in the preparation method of the iron-containing magnetic nano-ion, in step 1 and step 2, the acid used is 3.5-4.5wt% hydrochloric acid aqueous solution, the mass ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate is 3.5-3:1, and the mass ratio of ferrous chloride tetrahydrate to iron powder is 14-16:1.

[0026] In some embodiments of the present application, in the preparation method of the iron-containing magnetic nano-ion, the basic substance of step 3 is 20-30wt% ammonia water.

[0027] In some embodiments of the present application, in the preparation method of the iron-containing magnetic nano-ion, the post-treatment involved in step 3 includes but is not limited to stirring, standing, filtering, and washing.

[0028] In some embodiments of the present application, the preparation of the chitosan@titanium dioxide composite material loaded with chitosan includes the following steps:

[0029] Step 1: pretreatment of attapulgite;

[0030] Step 2: prepare a pretreated chitosan solution, then add the pretreated attapulgite of step 1, and post-treat to obtain an intermediate;

[0031] Step 3: add the prepared intermediate to the prepared tetrabutyl titanate solution, continue to add an alcohol-containing mixed solution, and post-treat to obtain the chitosan@titanium dioxide composite material loaded with chitosan.

[0032] In some embodiments of the present application, the post-treatment of step 2 in the preparation method of the chitosan@titanium dioxide composite material includes, but is not limited to, stirring, centrifugation, and drying.

[0033] In some embodiments of the present application, the post-treatment of step 3 in the preparation method of the chitosan@titanium dioxide composite material includes, but is not limited to, stirring and drying.

[0034] In some embodiments of the present application, the pretreatment of attapulgite is as follows: mixing attapulgite and 4-5 mol / L hydrochloric acid, stirring at room temperature for 3-4 hours, and the concentration of attapulgite is 235-245 g / L. After post-treatment, the pretreated attapulgite is obtained.

[0035] In some embodiments of the present application, the post-treatment of the pretreatment of attapulgite includes, but is not limited to, stirring, centrifugation, washing, drying, and grinding.

[0036] In some embodiments of the present application, the pretreated chitosan solution is prepared by pretreating chitosan with an acid solution.

[0037] In some embodiments of the present application, in order to fully swell the chitosan, the acid solution used for pretreating chitosan includes, but is not limited to, 0.8-1.2 v / v% glacial acetic acid and / or oxalic acid, and the mass fraction of chitosan is 0.4-0.6% during swelling.

[0038] In some embodiments of the present application, in step 3 of the preparation of the chitosan@titanium dioxide composite material, the tetrabutyl titanate solution is prepared by dissolving tetrabutyl titanate in ethanol, and adding glacial acetic acid to prevent hydrolysis.

[0039] In some embodiments of the present application, the alcohol-containing mixed solution includes, but is not limited to, a mixture of an alcohol solvent, distilled water, and an acid solvent.

[0040] In some embodiments of the present application, in step 3 of the preparation of the chitosan@titanium dioxide composite material, the alcohol-containing mixed solution is a mixed solution with a volume ratio of anhydrous ethanol:distilled water:nitric acid of 1:0.5:0.05, and the volume ratio of tetrabutyl titanate to the intermediate is 1.2-1.4 mL:1 g.

[0041] In some embodiments of the present application, the coagulant aid is at least one of polyacrylamide and starch.

[0042] In some embodiments of the present application, the coagulant aid can be a mixture of polyacrylamide and starch, or can be polyacrylamide or starch alone.

[0043] The present application provides an attapulgite composite material prepared by the aforementioned preparation method.

[0044] Compared with the prior art, the present application has the beneficial effects that: 1. less affected by temperature: the attapulgite composite material of the present application has almost the same adsorption capacity for organic and inorganic substances at a lower temperature (10℃) as at 25℃, is not affected by temperature, and expands the application scenarios of the material; 2. has high adsorption capacity for chromium ions, mercury ions and Congo red dye, and even if the temperature is lowered, the adsorption capacity for chromium ions, mercury ions and Congo red dye is not significantly reduced, and the adsorption capacity for heavy metal ions and dyes is high; 3. the raw materials are simple and easy to obtain, reducing the cost of preparing the attapulgite composite material for wastewater treatment. DETAILED DESCRIPTION

[0045] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0046] In the following examples, the loaded chitosan@titanium dioxide composite material, modified chitosan material, iron-containing magnetic nano ion, and chitosan composite flocculant are self-made, and the remaining used compound monomers and related reagents can be purchased from the market, wherein the attapulgite is purchased from Guangzhou Yifeng Chemical Technology Co., Ltd.; the chitosan is purchased from Shaanxi Haoyun Pharmaceutical Technology Co., Ltd., and the degree of deacetylation is 90%; the polyacrylamide is purchased from Jiangsu Zhonghao Yuanda Environmental Engineering Co., Ltd., which is a cationic polyacrylamide; and the starch is purchased from Suzhou Haoheng Chemical Co., Ltd.

[0047] 1. Preparation of the loaded chitosan@titanium dioxide composite material, comprising the following steps:

[0048] Step 1.1: Mix attapulgite and 4.5 mol / L hydrochloric acid to prepare a suspension with a concentration of 240 g / L, then stir at a temperature of 25℃ for 3.5 h, centrifuge, wash, dry, grind, and pass through a 200-mesh sieve to prepare pretreated attapulgite;

[0049] Step 1.2: Dissolve 1 g of chitosan in 500 mL of 1% ice acetic acid solution and stir until the chitosan is completely dissolved, then add 80 g of pretreated attapulgite and continue stirring for 4 h, then centrifuge, wash, dry, grind, and pass through a 200-mesh sieve to prepare an intermediate, wherein the stirring reaction of step 1.2 is carried out at a temperature of 65℃;

[0050] Step 1.3: 13 mL of tetrabutyl titanate was slowly dripped into 40 mL of anhydrous ethanol, then 3 mL of glacial acetic acid was added while stirring, and then 10 g of the intermediate was added after stirring for 20 min, and then 20 mL of an alcohol-containing mixed solution (the alcohol-containing mixed solution was mixed by anhydrous ethanol, distilled water and nitric acid in a volume ratio of 1:0.5:0.05) was added, and the mixture was stirred until a sol was formed, and then the sol was dried, ground, and sieved through a 200-mesh screen to obtain the chitosan@titanium dioxide composite material A, wherein the reaction of step 1.3 was carried out at a temperature of 65°C.

[0051] 2. Preparation of modified chitosan material, comprising the following steps:

[0052] Step 2.1: Attapulgite and 4.5 mol / L hydrochloric acid were mixed to obtain a suspension with a concentration of 240 g / L, and then stirred at a temperature of 25°C for 3.5 h, and then centrifuged, washed, dried, ground, and sieved through a 200-mesh screen to obtain pretreated attapulgite;

[0053] Step 2.2: 1 g of chitosan was dissolved in 500 mL of a 1% glacial acetic acid solution and stirred until the chitosan was completely dissolved, and then 80 g of the pretreated attapulgite was added and stirred for 4 h, and then centrifuged, washed, dried, ground, and sieved through a 200-mesh screen to obtain the modified chitosan material A, wherein the stirring reaction of step 2.2 was carried out at a temperature of 65°C.

[0054] 3. Preparation of chitosan composite flocculant, the raw materials of the chitosan composite flocculant include iron-containing magnetic nano-ions, sodium silicate, aluminum sulfate, zinc sulfate, and chitosan, wherein the preparation method of the iron-containing magnetic nano-ions is as follows:

[0055] Step 1: 10 g of ferric chloride hexahydrate was dissolved in 130 mL of a 4% hydrochloric acid solution;

[0056] Step 2: 3 g of ferrous chloride tetrahydrate was dissolved in 130 mL of a 4% hydrochloric acid solution, and then 0.2 g of iron powder was added;

[0057] Step 3: The substances of steps 1 and 2 were mixed, 20 mL of 25% ammonia water was added, stirred for 1.5 h, and then allowed to stand for 5 h, and then the solid was collected, washed with deionized water and anhydrous ethanol three times, and then dried and ground to obtain the iron-containing magnetic nano-ions A, and the particle size of the obtained iron-containing magnetic nano-ions A was 10-15 nm.

[0058] The preparation method of the chitosan composite flocculant A, comprising the following steps:

[0059] Step 1: iron-containing magnetic nano-ions were added to deionized water to prepare a solution with a concentration of 1.5 g / L and a volume of 600 mL, then 1.6 g of sodium silicate was added, and the pH of the mixed solution was adjusted to 1 using 30% concentrated sulfuric acid and 0.1 mol / L sodium hydroxide solution. After stirring at 42℃ for 2 h and standing for 2 h, a pretreatment solution was prepared.

[0060] Step 2: aluminum sulfate octadecahydrate and water were prepared into an aluminum sulfate solution with a concentration of 0.4 mol / L, 300 mL; zinc sulfate heptahydrate and water were prepared into a zinc sulfate solution with a concentration of 0.78 mol / L, 100 mL; chitosan was dissolved in a 1% ice acetic acid solution and stirred until the chitosan was completely dissolved to prepare a pretreated chitosan solution with a mass fraction of 0.5%, 100 mL; the aluminum sulfate solution, zinc sulfate solution, and pretreated chitosan solution were mixed, then the pretreatment solution prepared in step 1 was added, and stirred at 42℃ for 2 h and standing for 24 h to prepare chitosan composite flocculant A.

[0061] The preparation method of chitosan composite flocculant B comprises the following steps:

[0062] Step 1: iron-containing magnetic nano-ions were added to deionized water to prepare a solution with a concentration of 1.45 g / L and a volume of 620 mL, then 1.58 g of sodium silicate was added, and the pH was adjusted to 1. After stirring at 40℃ for 2 h and standing for 2 h, a pretreatment solution was prepared.

[0063] Step 2: aluminum sulfate octadecahydrate and water were prepared into an aluminum sulfate solution with a concentration of 0.42 mol / L, 290 mL; zinc sulfate heptahydrate and water were prepared into a zinc sulfate solution with a concentration of 0.82 mol / L, 96 mL; chitosan was dissolved in a 1% ice acetic acid solution and stirred until the chitosan was completely dissolved to prepare a pretreated chitosan solution with a mass fraction of 0.5%, 100 mL; the aluminum sulfate solution, zinc sulfate solution, and pretreated chitosan solution were mixed, then the pretreatment solution was added, and stirred at 40℃ for 2 h and standing for 24 h to prepare chitosan composite flocculant B.

[0064] The preparation method of attapulgite composite material for wastewater treatment in examples 1-5 and comparative examples 1-4 comprises the following steps:

[0065] The attapulgite composite material for wastewater treatment was prepared by uniformly mixing the chitosan@titanium dioxide composite material, coagulant aid, and chitosan composite flocculant. The stirring speed during mixing was 100 r / min.

[0066] The components required in examples 1-5 and comparative examples 1-4 and the content of each component are shown in Table 1:

[0067] Table 1:

[0068]

[0069]

[0070] The attapulgite composite materials for wastewater treatment prepared in Examples 1-5 and Comparative Examples 1-4 were respectively subjected to heavy metal ion adsorption capacity and dye adsorption capacity tests, and the test methods were as follows:

[0071] Heavy metal ion adsorption experiment:

[0072] 100 mL of a heavy metal ion solution with a mass concentration of 500 mg / L was prepared and the pH of the solution was adjusted to 3, then the prepared heavy metal ion solution was placed under a temperature condition of 10°C and / or 25°C, 0.2 g of the attapulgite composite material for wastewater treatment prepared in Examples 1-5 and Comparative Examples 1-4 was added respectively, and after sufficient mixing, it was placed for 4 h, magnetically separated, the concentration of heavy metal ions in the solution was determined, and the heavy metal ion adsorption capacity was calculated, and the calculation formula was as follows:

[0073] Q1 = (C0-C1) x V / M; wherein Q1 is the adsorption capacity (unit: mg / g), C0 is the concentration of the heavy metal ion solution before adsorption (unit: mg / L), C1 is the concentration of the heavy metal ion solution after adsorption (unit: mg / L), V is the volume of the heavy metal ion solution (unit: L), and M is the dosage of the attapulgite composite material for wastewater treatment (unit: g).

[0074] Dye adsorption experiment:

[0075] 100 mL of a dye solution with a mass concentration of 500 mg / L was prepared and the pH of the solution was adjusted to 3, then the prepared dye solution was placed under a temperature condition of 10°C and / or 25°C, 0.3 g of the attapulgite composite material for wastewater treatment prepared in Examples 1-5 and Comparative Examples 1-4 was added respectively, and after sufficient mixing, it was placed for 4 h, magnetically separated, the upper clear liquid was taken, and the concentration of the dye solution at the start and at equilibrium was determined at the maximum absorption wavelength by a spectrophotometer, and the dye adsorption capacity was calculated, and the calculation formula was as follows:

[0076] Q1 = (C0-C1) x V / M; wherein Q1 is the adsorption capacity (unit: mg / g), C0 is the initial concentration of the dye solution (unit: mg / L), C1 is the equilibrium concentration of the dye solution (unit: mg / L), V is the volume of the dye solution (unit: L), and M is the dosage of the attapulgite composite material for wastewater treatment (unit: g).

[0077] The test results are shown in Table 2, and are as follows:

[0078] Table 2:

[0079]

[0080]

[0081] It can be seen from the comparison of Example 1 and Comparative Examples 1-2 that, compared with the use of the loaded chitosan@titanium dioxide composite material or the use of the chitosan composite flocculant and the coagulant together, the attapulgite composite material for wastewater treatment prepared by using the chitosan composite flocculant and the loaded chitosan@titanium dioxide composite material together has higher adsorption amounts of chromium ions and mercury ions and higher adsorption amount of Congo red dye under low temperature conditions.

[0082] It can be seen from the comparison of Example 1 and Comparative Examples 3-4 that, the attapulgite composite material for wastewater treatment prepared by using the chitosan composite flocculant and the loaded chitosan@titanium dioxide composite material together has high adsorption amounts of chromium ions and mercury ions and high adsorption amount of Congo red dye under normal temperature conditions, and even if the temperature is reduced, the adsorption amounts of chromium ions and mercury ions and Congo red dye do not decrease obviously.

[0083] It can be seen from the comparison of Example 1 and Examples 4-5 that, when the mass ratio of the chitosan composite flocculant and the loaded chitosan@titanium dioxide composite material is within a proper mass range, the adsorption amounts of chromium ions and mercury ions and the adsorption amount of Congo red dye under low temperature conditions can be improved, and even if the temperature is reduced, the adsorption amounts of chromium ions and mercury ions and Congo red dye do not decrease obviously.

[0084] It can be seen from the comparison of Example 1 and Examples 3 that, the attapulgite composite material for wastewater treatment prepared by using the preparation method provided by the application has high adsorption amounts of chromium ions and mercury ions and high adsorption amount of Congo red dye under normal temperature conditions, and even if the temperature is reduced, the adsorption amounts of chromium ions and mercury ions and Congo red dye do not decrease obviously, and the adsorption amounts of heavy metal ions and dyes are high under normal temperature or low temperature conditions.

[0085] In summary, the attapulgite composite material for wastewater treatment prepared by the application has high adsorption amounts of chromium ions and mercury ions and high adsorption amount of Congo red dye, and even if the temperature is reduced, the adsorption amounts of chromium ions and mercury ions and Congo red dye do not decrease obviously, and the adsorption amounts of heavy metal ions and dyes are high; and the raw materials for preparing the attapulgite composite material for wastewater treatment are simple and easy to obtain, thereby reducing the cost of preparing the attapulgite composite material for wastewater treatment.

Claims

1. A method for preparing an attapulgite composite material for wastewater treatment, characterized in that: The following steps are involved: (1) Preparation of chitosan@titanium dioxide loaded composite materials; (2) Preparation of chitosan composite flocculant; (3) The loaded chitosan@titanium dioxide composite material, the coagulant aid and the chitosan composite flocculant were mixed to prepare the concave soil composite material for wastewater treatment.

2. The method for preparing the attapulgite composite material for wastewater treatment according to claim 1, wherein: The mass ratio of the loaded chitosan@titanium dioxide composite material to the chitosan composite flocculant is 1:0.4-0.

7.

3. The method for preparing the attapulgite composite material for wastewater treatment according to claim 1, wherein: The raw materials for preparing the chitosan composite flocculant include iron-containing magnetic nano-ions, sodium silicate, aluminum sulfate, zinc sulfate and chitosan.

4. The method for preparing the attapulgite composite material for wastewater treatment according to claim 2, wherein: The preparation method of the chitosan composite flocculant comprises the following steps: Step 1: After preparing a solution containing iron-containing magnetic nanoparticles, sodium silicate is added, and the pH is adjusted to 1-3, and the mixture is stirred and aged to obtain a pretreatment solution; Step 2: After mixing the aluminum sulfate solution, the zinc sulfate solution and the pretreated chitosan solution, the pretreated solution is added and post-treated to obtain a chitosan composite flocculant.

5. The method for preparing the attapulgite composite material for wastewater treatment according to claim 3 or 4, characterized in that: The preparation method of iron-containing magnetic nanoparticles comprises the following steps: Step 1: dissolving ferric chloride hexahydrate in an acid solution; Step 2: dissolving ferrous chloride tetrahydrate in an acid solution, and then adding iron powder; Step 3: After mixing the materials in step 1 and step 2, adding alkaline material, and post-treating, to obtain iron-containing magnetic nanoparticles.

6. The method for preparing the attapulgite composite material for wastewater treatment according to claim 3 or 4, characterized in that: The aluminum sulfate is aluminum sulfate 18hydrate, and the zinc sulfate is zinc sulfate heptahydrate.

7. The method for preparing the attapulgite composite material for wastewater treatment according to claim 1, characterized in that: The preparation of the loaded chitosan@titanium dioxide composite material comprises the following steps: Step 1: attapulgite pretreatment; Step 2: preparing a pretreated chitosan solution, then adding the pretreated attapulgite from step 1, and post-treating to obtain an intermediate; Step 3: adding the prepared intermediate to the prepared tetrabutyl titanate solution, and then adding the alcohol-containing mixed solution, and post-treating to obtain the loaded chitosan@titanium dioxide composite material.

8. The method for preparing the attapulgite composite material for wastewater treatment according to claim 4 or 7, characterized in that: The pretreated chitosan solution is chitosan pretreated with an acid solution.

9. The method for preparing the attapulgite composite material for wastewater treatment according to claim 1, wherein: The coagulant aid is at least one of polyacrylamide and starch.

10. The attapulgite composite material for wastewater treatment obtained by the method for preparing the attapulgite composite material for wastewater treatment according to any one of claims 1 to 9.

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