Environment-friendly flocculant for sewage treatment and preparation method thereof

Abstract

The present application relates to the technical field of flocculants, in particular to an environment-friendly sewage treatment flocculant and a preparation method thereof, which comprises the following raw materials in parts by weight: modified microemulsion 30-35 parts, composite additive 4-6 parts, polyferric sulfate 2-3 parts, activated carbon 2-3 parts, ethylene glycol 5-10 parts and water 60-70 parts; by adding the modified microemulsion and the composite additive, the oil, microplastics, phosphorus and heavy metals in domestic sewage can be effectively removed; meanwhile, due to the compounding between the modified microemulsion and the composite additive, the purification effect is greatly enhanced, solving the problem of insufficient removal effect of microplastics, phosphorus and heavy metals by the existing flocculants.

Description

Technical Field

[0001] This invention relates to the field of flocculant technology, specifically to an environmentally friendly wastewater treatment flocculant and its preparation method. Background Technology

[0002] With urban development and population growth, the discharge of urban domestic sewage is increasing day by day. Domestic sewage mainly contains substances such as grease, microplastics, phosphorus, and heavy metals, so it is necessary to treat domestic sewage. The commonly used sewage treatment method is to use flocculants to decompose or precipitate the chemical substances in sewage, thereby playing a purification role. Most of the commonly used flocculants are iron-based inorganic flocculants. However, they are prone to corroding pipes and equipment, thus affecting water quality. Organic polyacrylamide can no longer meet market demand for the removal of microplastics, phosphorus, and heavy metals. Summary of the Invention

[0003] The purpose of this invention is to provide an environmentally friendly wastewater treatment flocculant and its preparation method, which solves the problem that existing flocculants are not effective in removing microplastics, phosphorus and heavy metals.

[0004] The objective of this invention can be achieved through the following technical solution: a method for preparing an environmentally friendly wastewater treatment flocculant, comprising the following steps: weighing the following parts by weight of raw materials: 30-35 parts of modified microemulsion, 4-6 parts of composite additives, 2-3 parts of polyferric sulfate, 2-3 parts of activated carbon, 5-10 parts of ethylene glycol and 60-70 parts of water; mixing the modified microemulsion, composite additives, polyferric sulfate, activated carbon, ethylene glycol and water to obtain an environmentally friendly wastewater treatment flocculant;

[0005] The modified microemulsion is prepared through the following steps:

[0006] Step A1: Mix β-cyclodextrin, sodium hydroxide solution and deionized water, stir at 80-100 rpm and 5°C, add p-toluenesulfonyl chloride and acetonitrile, react for 2-3 h to obtain intermediate 1. Mix chitosan and acetic acid solution, stir at 120-140 rpm and 100°C, add intermediate 1 and N,N-dimethylformamide, react for 10-12 h, then add maleic anhydride, react for 3-4 h to obtain modified chitosan.

[0007] The sodium hydroxide solution has a mass fraction of 10%, and the ratio of β-cyclodextrin, sodium hydroxide solution, and p-toluenesulfonyl chloride is 12-14 g: 5-6 mL: 2.5-2.6 g; the acetic acid solution has a volume fraction of 40%, and the ratio of chitosan, acetic acid solution, intermediate 1, and maleic anhydride is 10-12 g: 300-350 mL: 5-6 g: 0.02-0.03 mol;

[0008] During the reaction, under alkaline conditions, the hydroxyl group in β-cyclodextrin reacts with the sulfonic acid chloride in p-toluenesulfonyl chloride to obtain intermediate 1. Intermediate 1 then reacts with the amino group in chitosan to form a secondary amine, thereby grafting β-cyclodextrin onto the chitosan chain. Maleic anhydride is then added to react with hydroxymethyl or unreacted amino groups to introduce double bonds and obtain modified chitosan.

[0009] Step A2: Mix liquid paraffin, Span-80, Tween-80 and n-butanol, and stir for 30 min at a stirring speed of 800 rpm and a temperature of 50°C to obtain an oil phase. Mix acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and deionized water, and stir at a stirring speed of 300 rpm and a temperature of 30°C while adding ammonium persulfate solution, and stir for 30 min to obtain an aqueous phase. Slowly add the aqueous phase dropwise to the oil phase, and react at a temperature of 40°C for 3-4 h. Demulsify, dry, and obtain the modified microemulsion.

[0010] The ratio of liquid paraffin, Span-80, Tween-80, and n-butanol is 7-8 g: 2.3-2.5 g: 1.5-1.7 g: 0.4-0.5 g; the mass fraction of ammonium persulfate solution is 1%; the ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan, and ammonium persulfate solution is 0.05-0.052 mol: 0.01-0.015 mol: 0.04-0.05 g: 0.8-0.9 g: 1-1.2 mL.

[0011] During the reaction, a modified microemulsion was prepared by reverse microemulsion polymerization using ammonium persulfate as an initiator and acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide and modified chitosan as monomers.

[0012] The composite additive is prepared by the following steps:

[0013] Step B1: Mix 4-bromobenzoic acid, ethanol and concentrated sulfuric acid, and react at a stirring rate of 120-150 rpm and a temperature of 75°C for 12 h to obtain intermediate 1'. Mix intermediate 1' with diethyl ether, and stir at a stirring rate of 80-100 rpm and a temperature of 5°C, and add n-butyllithium. Stir for 2-3 h, raise the temperature to room temperature and add trichlorosilane, and react for 12 h to obtain intermediate 2.

[0014] The concentrated sulfuric acid has a mass fraction of 95%, and the ratio of 4-bromobenzoic acid, ethanol, and concentrated sulfuric acid is 0.1-0.11 mol: 500 mL: 10-11 mL; the ratio of intermediate 1', n-butyllithium, and trichlorosilane is 0.02-0.022 mol: 8-10 mL: 0.005-0.006 mol.

[0015] During the reaction, under the action of concentrated sulfuric acid, the carboxyl group in 4-bromobenzoic acid reacts with ethanol to form an ethyl formate structure, thus obtaining intermediate 1'. Then, under the action of n-butyllithium as an initiator, trichlorosilane is first lithiated and then reacts with intermediate 1' to form a carbon-silicon bond, thus obtaining intermediate 2.

[0016] Step B2: Mix intermediate 2, vinyl ferrocene and tetrahydrofuran, stir at 120-150 rpm and 90°C, add caster catalyst, and react for 3-4 h to obtain intermediate 3. Mix intermediate 3, sodium hydroxide and deionized water, stir at 60-80 rpm and 80°C for 2-3 h, cool to room temperature, add hydrochloric acid solution to obtain intermediate 4.

[0017] The ratio of intermediate 2, vinyl ferrocene, and cassiterite catalyst is 0.05-0.06 mol: 0.07-0.08 mol: 0.8-0.9 g; the hydrochloric acid solution has a mass fraction of 35%; the ratio of intermediate 3, sodium hydroxide, deionized water, and hydrochloric acid solution is 0.05-0.06 mol: 18-20 g: 400-450 mL: 80-90 mL.

[0018] During the reaction, under the action of the cassiterite catalyst, the silane-hydrogen bond in intermediate 2 undergoes hydrosilylation with the double bond in vinyl ferrocene to obtain intermediate 3. The ester group in the ethyl formate structure of intermediate 3 is then broken under the action of sodium hydroxide and acidified to form a carboxyl group to obtain intermediate 4.

[0019] Step B3: Mix cobalt acetate, intermediate 4, polyvinylpyrrolidone and N,N-dimethylformamide, ultrasonically disperse for 20 min, react at 120℃ for 3 h, centrifuge, filter, and obtain the composite additive.

[0020] The ratio of cobalt acetate, intermediate 4, polyvinylpyrrolidone, and N,N-dimethylformamide is 0.012 mol: 0.012 mol: 3.5-3.8 g: 30-32 mL;

[0021] During the reaction, a composite auxiliary with a metal-organic framework structure was prepared by solvothermal method using cobalt acetate as the cobalt source and intermediate 4 as the ligand.

[0022] The beneficial effects of this invention: This invention discloses an environmentally friendly wastewater treatment flocculant and its preparation method. By adding modified microemulsions and composite additives, it can effectively remove grease, microplastics, phosphorus, and heavy metals from domestic wastewater. Furthermore, the combination of modified microemulsions and composite additives greatly enhances its purification effect. During the use of the flocculant, the modified microemulsion itself has a microsphere structure with a large number of cyclodextrins on its surface, and the presence of its cationic sulfonic acid groups allows the modified microemulsion to neutralize charges and adsorb and bridge particles in the wastewater. This destabilizes and flocculates the particles in the system. The composite additive itself has a porous metal-organic framework structure. Since it uses zirconium as the metal element and introduces silicon, it has a good adsorption effect on phosphorus and heavy metal ions. Its structure also avoids the corrosion of pipelines during the use of polyferric sulfate. At the same time, due to the host-guest inclusion effect of the cyclodextrin structure in the modified microemulsion and the ferrocene in the composite additive, the micro-crosslinked network structure formed not only makes it settle quickly, but also captures more pollutant particles during the settling process, thus playing a good purification role. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 A method for preparing an environmentally friendly wastewater treatment flocculant, comprising the following steps: weighing the following raw materials in parts by weight: 30 parts modified microemulsion, 4 parts composite additive, 2 parts commercially available Jiuyue polyferric sulfate, 2 parts commercially available Jinding activated carbon, 5 parts ethylene glycol and 60 parts water; mixing the modified microemulsion, composite additive, polyferric sulfate, activated carbon, ethylene glycol and water to obtain an environmentally friendly wastewater treatment flocculant;

[0025] The modified microemulsion is prepared through the following steps:

[0026] Step A1: Mix β-cyclodextrin, sodium hydroxide solution and deionized water, stir at 80 rpm and 5°C, add p-toluenesulfonyl chloride and acetonitrile, react for 2 h to obtain intermediate 1. Mix commercially available chitosan and acetic acid solution, stir at 120 rpm and 100°C, add intermediate 1 and N,N-dimethylformamide, react for 10 h, then add maleic anhydride, react for 3-4 h to obtain modified chitosan.

[0027] The sodium hydroxide solution has a mass fraction of 10%, and the ratio of β-cyclodextrin, sodium hydroxide solution, and p-toluenesulfonyl chloride is 12g:5mL:2.5g; the acetic acid solution has a volume fraction of 40%, and the ratio of chitosan, acetic acid solution, intermediate 1, and maleic anhydride is 10g:300mL:5g:0.02mol;

[0028] Step A2: Mix commercially available Zhijia liquid paraffin, Span-80, Tween-80 and n-butanol, and stir for 30 min at a stirring speed of 800 rpm and a temperature of 50℃ to obtain an oil phase. Mix acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and deionized water, and stir at a stirring speed of 300 rpm and a temperature of 30℃ while adding ammonium persulfate solution, and stir for 30 min to obtain an aqueous phase. Slowly add the aqueous phase dropwise to the oil phase, and react for 3 h at a temperature of 40℃. Demulsify, dry, and obtain a modified microemulsion.

[0029] The ratio of liquid paraffin, Span-80, Tween-80, and n-butanol was 7 g: 2.3 g: 1.5 g: 0.4 g; the mass fraction of ammonium persulfate solution was 1%; and the ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan, and ammonium persulfate solution was 0.05 mol: 0.01 mol: 0.04 g: 0.8 g: 1 mL.

[0030] The composite additive is prepared by the following steps:

[0031] Step B1: Mix 4-bromobenzoic acid, ethanol and concentrated sulfuric acid, and react at a stirring rate of 120 rpm and a temperature of 75°C for 12 h to obtain intermediate 1'. Mix intermediate 1' with diethyl ether, and stir at a stirring rate of 80 rpm and a temperature of 5°C, and add n-butyllithium. Stir for 2 h, raise the temperature to room temperature and add trichlorosilane, and react for 12 h to obtain intermediate 2.

[0032] The mass fraction of concentrated sulfuric acid is 95%, and the ratio of 4-bromobenzoic acid, ethanol and concentrated sulfuric acid is 0.1 mol: 500 mL: 10 mL; the ratio of intermediate 1', n-butyllithium and trichlorosilane is 0.02 mol: 8 mL: 0.005 mol.

[0033] Step B2: Mix intermediate 2, vinyl ferrocene and tetrahydrofuran, stir at 120 rpm and 90°C, add caster catalyst, and react for 3 h to obtain intermediate 3. Mix intermediate 3, sodium hydroxide and deionized water, stir at 60 rpm and 80°C for 2 h, cool to room temperature, add hydrochloric acid solution to obtain intermediate 4.

[0034] The ratio of intermediate 2, vinyl ferrocene, and cassiterite catalyst was 0.05 mol: 0.07 mol: 0.8 g; the hydrochloric acid solution had a mass fraction of 35%; the ratio of intermediate 3, sodium hydroxide, deionized water, and hydrochloric acid solution was 0.05 mol: 18 g: 400 mL: 80 mL.

[0035] Step B3: Mix cobalt acetate, intermediate 4, polyvinylpyrrolidone and N,N-dimethylformamide, ultrasonically disperse for 20 min, react at 120℃ for 3 h, centrifuge, filter, and obtain the composite additive.

[0036] The ratio of cobalt acetate, intermediate 4, polyvinylpyrrolidone, and N,N-dimethylformamide was 0.012 mol: 0.012 mol: 3.5 g: 30 mL.

[0037] Example 2 A method for preparing an environmentally friendly wastewater treatment flocculant, comprising the following steps: Weighing the following raw materials in parts by weight: 30 parts modified microemulsion, 6 parts composite additive, 3 parts commercially available Jiuyue polyferric sulfate, 3 parts commercially available Jinding activated carbon, 10 parts ethylene glycol and 70 parts water; mixing the modified microemulsion, composite additive, polyferric sulfate, activated carbon, ethylene glycol and water to obtain an environmentally friendly wastewater treatment flocculant;

[0038] The modified microemulsion is prepared through the following steps:

[0039] Step A1: Mix β-cyclodextrin, sodium hydroxide solution and deionized water, stir at 100 rpm and 5°C, add p-toluenesulfonyl chloride and acetonitrile, react for 3 h to obtain intermediate 1. Mix commercially available Honghai chitosan and acetic acid solution, stir at 120 rpm and 100°C, add intermediate 1 and N,N-dimethylformamide, react for 12 h, then add maleic anhydride, react for 3-4 h to obtain modified chitosan.

[0040] The sodium hydroxide solution has a mass fraction of 10%, and the ratio of β-cyclodextrin, sodium hydroxide solution, and p-toluenesulfonyl chloride is 14g:5mL:2.5g; the acetic acid solution has a volume fraction of 40%, and the ratio of chitosan, acetic acid solution, intermediate 1, and maleic anhydride is 12g:300mL:5g:0.03mol;

[0041] Step A2: Mix commercially available Zhijia liquid paraffin, Span-80, Tween-80 and n-butanol, and stir for 30 min at a stirring speed of 800 rpm and a temperature of 50℃ to obtain an oil phase. Mix acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and deionized water, and stir at a stirring speed of 300 rpm and a temperature of 30℃ while adding ammonium persulfate solution, and stir for 30 min to obtain an aqueous phase. Slowly add the aqueous phase dropwise to the oil phase, and react at a temperature of 40℃ for 3-4 h. Demulsify, dry, and obtain a modified microemulsion.

[0042] The ratio of liquid paraffin, Span-80, Tween-80, and n-butanol was 8 g: 2.3 g: 1.7 g: 0.4 g; the mass fraction of ammonium persulfate solution was 1%; and the ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan, and ammonium persulfate solution was 0.052 mol: 0.01 mol: 0.05 g: 0.8 g: 1.2 mL.

[0043] The composite additive is prepared by the following steps:

[0044] Step B1: Mix 4-bromobenzoic acid, ethanol and concentrated sulfuric acid, and react at a stirring rate of 150 rpm and a temperature of 75°C for 12 h to obtain intermediate 1'. Mix intermediate 1' with diethyl ether, and stir at a stirring rate of 80 rpm and a temperature of 5°C, and add n-butyllithium. Stir for 3 h, raise the temperature to room temperature and add trichlorosilane, and react for 12 h to obtain intermediate 2.

[0045] The mass fraction of concentrated sulfuric acid is 95%, and the ratio of 4-bromobenzoic acid, ethanol and concentrated sulfuric acid is 0.11 mol: 500 mL: 10 mL; the ratio of intermediate 1', n-butyllithium and trichlorosilane is 0.02 mol: 10 mL: 0.005 mol.

[0046] Step B2: Mix intermediate 2, vinyl ferrocene and tetrahydrofuran, stir at 120 rpm and 90°C, add caster catalyst, and react for 4 h to obtain intermediate 3. Mix intermediate 3, sodium hydroxide and deionized water, stir at 80 rpm and 80°C for 2 h, cool to room temperature, add hydrochloric acid solution to obtain intermediate 4.

[0047] The ratio of intermediate 2, vinyl ferrocene, and cassiterite catalyst was 0.06 mol: 0.07 mol: 0.9 g; the hydrochloric acid solution had a mass fraction of 35%; the ratio of intermediate 3, sodium hydroxide, deionized water, and hydrochloric acid solution was 0.06 mol: 18 g: 450 mL: 80 mL.

[0048] Step B3: Mix cobalt acetate, intermediate 4, polyvinylpyrrolidone and N,N-dimethylformamide, ultrasonically disperse for 20 min, react at 120℃ for 3 h, centrifuge, filter, and obtain the composite additive.

[0049] The ratio of cobalt acetate, intermediate 4, polyvinylpyrrolidone, and N,N-dimethylformamide was 0.012 mol: 0.012 mol: 3.5 g: 32 mL.

[0050] Example 3 A method for preparing an environmentally friendly wastewater treatment flocculant, comprising the following steps: Weighing the following raw materials in parts by weight: 35 parts modified microemulsion, 6 parts composite additive, 3 parts commercially available Jiuyue polyferric sulfate, 3 parts commercially available Jinding activated carbon, 10 parts ethylene glycol and 70 parts water; mixing the modified microemulsion, composite additive, polyferric sulfate, activated carbon, ethylene glycol and water to obtain an environmentally friendly wastewater treatment flocculant;

[0051] The modified microemulsion is prepared through the following steps:

[0052] Step A1: Mix β-cyclodextrin, sodium hydroxide solution and deionized water, stir at 100 rpm and 5°C, add p-toluenesulfonyl chloride and acetonitrile, react for 3 h to obtain intermediate 1. Mix commercially available Honghai chitosan and acetic acid solution, stir at 140 rpm and 100°C, add intermediate 1 and N,N-dimethylformamide, react for 12 h, then add maleic anhydride, react for 4 h to obtain modified chitosan.

[0053] The sodium hydroxide solution had a mass fraction of 10%, and the ratio of β-cyclodextrin, sodium hydroxide solution, and p-toluenesulfonyl chloride was 14 g: 6 mL: 2.6 g; the acetic acid solution had a volume fraction of 40%, and the ratio of chitosan, acetic acid solution, intermediate 1, and maleic anhydride was 12 g: 350 mL: 6 g: 0.03 mol.

[0054] Step A2: Mix commercially available Zhijia liquid paraffin, Span-80, Tween-80 and n-butanol, and stir for 30 min at a stirring speed of 800 rpm and a temperature of 50℃ to obtain an oil phase. Mix acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and deionized water, and stir at a stirring speed of 300 rpm and a temperature of 30℃ while adding ammonium persulfate solution, and stir for 30 min to obtain an aqueous phase. Slowly add the aqueous phase dropwise to the oil phase, and react for 4 h at a temperature of 40℃. Demulsify, dry, and obtain a modified microemulsion.

[0055] The ratio of liquid paraffin, Span-80, Tween-80, and n-butanol was 8 g: 2.5 g: 1.5-1.7 g: 0.5 g; the mass fraction of ammonium persulfate solution was 1%; and the ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan, and ammonium persulfate solution was 0.052 mol: 0.015 mol: 0.05 g: 0.9 g: 1.2 mL.

[0056] The composite additive is prepared by the following steps:

[0057] Step B1: Mix 4-bromobenzoic acid, ethanol and concentrated sulfuric acid, and react at a stirring rate of 150 rpm and a temperature of 75°C for 12 h to obtain intermediate 1'. Mix intermediate 1' with diethyl ether, and stir at a stirring rate of 100 rpm and a temperature of 5°C, and add n-butyllithium. Stir for 3 h, raise the temperature to room temperature and add trichlorosilane, and react for 12 h to obtain intermediate 2.

[0058] The mass fraction of concentrated sulfuric acid is 95%, and the ratio of 4-bromobenzoic acid, ethanol and concentrated sulfuric acid is 0.11 mol: 500 mL: 11 mL; the ratio of intermediate 1', n-butyllithium and trichlorosilane is 0.022 mol: 10 mL: 0.006 mol.

[0059] Step B2: Mix intermediate 2, vinyl ferrocene and tetrahydrofuran, stir at 150 rpm and 90°C, add caster catalyst, and react for 3-4 h to obtain intermediate 3. Mix intermediate 3, sodium hydroxide and deionized water, stir at 80 rpm and 80°C for 3 h, cool to room temperature, add hydrochloric acid solution to obtain intermediate 4.

[0060] The ratio of intermediate 2, vinyl ferrocene, and cassiterite catalyst was 0.06 mol: 0.08 mol: 0.9 g; the hydrochloric acid solution had a mass fraction of 35%; the ratio of intermediate 3, sodium hydroxide, deionized water, and hydrochloric acid solution was 0.06 mol: 20 g: 450 mL: 90 mL.

[0061] Step B3: Mix cobalt acetate, intermediate 4, polyvinylpyrrolidone and N,N-dimethylformamide, ultrasonically disperse for 20 min, react at 120℃ for 3 h, centrifuge, filter, and obtain the composite additive.

[0062] The ratio of cobalt acetate, intermediate 4, polyvinylpyrrolidone, and N,N-dimethylformamide was 0.012 mol: 0.012 mol: 3.8 g: 32 mL.

[0063] Comparative Example 1: Compared with Example 3, this comparative example removes intermediate 1 from the preparation process of the modified microemulsion in Example 3, while the other steps are the same.

[0064] Comparative Example 2: Compared with Example 3, this comparative example removed 2-acrylamide-2-methylpropanesulfonic acid from the preparation process of the modified microemulsion in Example 3, while the other steps were the same.

[0065] Comparative Example 3: Compared with Example 3, the composite additive in the preparation process of the environmentally friendly wastewater treatment flocculant in Example 3 was replaced with commercially available ZIF-8 material, while the other steps were the same.

[0066] The environmentally friendly wastewater treatment flocculants prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 were used. Their chemical oxygen demand (COD) was determined according to GB 11914-89. Kaolin was used to simulate wastewater according to GB 13200-91, and the turbidity of the supernatant after flocculation was tested. A 50 mg / L copper ion solution was prepared, and the ion concentration after adsorption was measured. The removal efficiency was calculated. Using 0.1 mg / L hydrochloric acid and sodium hydroxide solution as elution and regeneration solutions, the performance retention rate was calculated after four adsorption-desorption cycles. The test results are shown in the table below.

[0067]

[0068] As shown in the table, the test results indicate that when comparing Examples 1, 2, and 3 with Comparative Examples 1, 2, and 3, Comparative Example 1 differs from Example 3 in that intermediate 1 in the preparation process of the modified microemulsion in Example 3 was removed. Due to the lack of cyclodextrin structure, its performance decreased significantly. Comparative Example 2 removed 2-acrylamide-2-methylpropanesulfonic acid in the preparation process of the modified microemulsion in Example 3. Due to the lack of cationic groups, its performance decreased significantly. In Comparative Example 3, the composite additive in the preparation process of the environmentally friendly wastewater treatment flocculant in Example 3 was replaced with commercially available ZIF-8 material. Since ZIF-8 material cannot form a micro-crosslinked network structure with the modified microemulsion, its performance decreased significantly.

[0069] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly wastewater treatment flocculant, characterized in that, The process includes the following steps: Weigh the following raw materials in parts by weight: 30-35 parts modified microemulsion, 4-6 parts composite additives, 2-3 parts polyferric sulfate, 2-3 parts activated carbon, 5-10 parts ethylene glycol, and 60-70 parts water. Mix the modified microemulsion, composite additives, polyferric sulfate, activated carbon, ethylene glycol, and water to prepare an environmentally friendly wastewater treatment flocculant. The modified microemulsion is prepared through the following steps: Step A1: Mix β-cyclodextrin, sodium hydroxide solution and deionized water, stir at 80-100 rpm and 5°C, add p-toluenesulfonyl chloride and acetonitrile, react for 2-3 h to obtain intermediate 1. Mix chitosan and acetic acid solution, stir at 120-140 rpm and 100°C, add intermediate 1 and N,N-dimethylformamide, react for 10-12 h, then add maleic anhydride, react for 3-4 h to obtain modified chitosan. Step A2: Mix liquid paraffin, Span-80, Tween-80 and n-butanol, and stir for 30 min at a stirring speed of 800 rpm and a temperature of 50°C to obtain an oil phase. Mix acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and deionized water, and stir at a stirring speed of 300 rpm and a temperature of 30°C while adding ammonium persulfate solution, and stir for 30 min to obtain an aqueous phase. Slowly add the aqueous phase dropwise to the oil phase, and react at a temperature of 40°C for 3-4 h. Demulsify, dry, and obtain the modified microemulsion. The composite additive is prepared by the following steps: Step B1: Mix 4-bromobenzoic acid, ethanol and concentrated sulfuric acid, and react at a stirring rate of 120-150 rpm and a temperature of 75°C for 12 h to obtain intermediate 1'. Mix intermediate 1' with diethyl ether, and stir at a stirring rate of 80-100 rpm and a temperature of 5°C, and add n-butyllithium. Stir for 2-3 h, raise the temperature to room temperature and add trichlorosilane, and react for 12 h to obtain intermediate 2. Step B2: Mix intermediate 2, vinyl ferrocene and tetrahydrofuran, stir at 120-150 rpm and 90°C, add caster catalyst, and react for 3-4 h to obtain intermediate 3. Mix intermediate 3, sodium hydroxide and deionized water, stir at 60-80 rpm and 80°C for 2-3 h, cool to room temperature, add hydrochloric acid solution to obtain intermediate 4. Step B3: Mix cobalt acetate, intermediate 4, polyvinylpyrrolidone and N,N-dimethylformamide, sonicate for 20 min, react at 120℃ for 3 h, centrifuge, filter, and obtain the composite additive.

2. The method for preparing an environmentally friendly wastewater treatment flocculant according to claim 1, characterized in that: In step A1: the mass fraction of sodium hydroxide solution is 10%, and the ratio of β-cyclodextrin, sodium hydroxide solution and p-toluenesulfonyl chloride is 12-14g: 5-6mL: 2.5-2.6g; the volume fraction of acetic acid solution is 40%, and the ratio of chitosan, acetic acid solution, intermediate 1 and maleic anhydride is 10-12g: 300-350mL: 5-6g: 0.02-0.03mol.

3. The method for preparing an environmentally friendly wastewater treatment flocculant according to claim 1, characterized in that: In step A2: the ratio of liquid paraffin, Span-80, Tween-80, and n-butanol is 7-8g. 2.3-2.5g: 1.5-1.7g: 0.4-0.5g; the mass fraction of ammonium persulfate solution is 1%, and the volume ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-methylenebisacrylamide, modified chitosan and ammonium persulfate solution is 0.05-0.052mol: 0.01-0.015mol: 0.04-0.05g: 0.8-0.9g: 1-1.2mL.

4. The method for preparing an environmentally friendly wastewater treatment flocculant according to claim 1, characterized in that: In step B1: the mass fraction of concentrated sulfuric acid is 95%, and the ratio of 4-bromobenzoic acid, ethanol and concentrated sulfuric acid is 0.1-0.11 mol: 500 mL: 10-11 mL; the ratio of intermediate 1', n-butyllithium and trichlorosilane is 0.02-0.022 mol: 8-10 mL: 0.005-0.006 mol.

5. The method for preparing an environmentally friendly wastewater treatment flocculant according to claim 1, characterized in that: In step B2: the ratio of intermediate 2, vinyl ferrocene, and cassiterite catalyst is 0.05-0.06 mol: 0.07-0.08 mol: 0.8-0.9 g; the mass fraction of hydrochloric acid solution is 35%; the ratio of intermediate 3, sodium hydroxide, deionized water, and hydrochloric acid solution is 0.05-0.06 mol: 18-20 g: 400-450 mL: 80-90 mL.

6. The method for preparing an environmentally friendly wastewater treatment flocculant according to claim 1, characterized in that: In step B3, the ratio of cobalt acetate, intermediate 4, polyvinylpyrrolidone, and N,N-dimethylformamide is 0.012 mol: 0.012 mol: 3.5-3.8 g: 30-32 mL.

7. An environmentally friendly wastewater treatment flocculant, characterized in that: It is prepared according to any one of the preparation methods described in claims 1-6.

Images