CN118307112B - Sewage treatment flocculant and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of sewage treatment, and discloses a sewage treatment flocculant and a preparation method thereof. The invention comprises the following steps: adding a sulfonic acid-quaternary ammonium salt copolymer, a bentonite-modified phenolic resin and chitosan into a stirrer, stirring, and obtaining the sewage treatment flocculant after stirring. The bentonite in the bentonite-modified phenolic resin has a large specific surface area and good adsorption capacity, and cations between montmorillonite layers can be well exchanged with chromium ions and lead ions in wastewater to achieve the effect of flocculation through adsorption. The sulfonic acid groups in the sulfonic acid-quaternary ammonium salt copolymer contain sulfur atoms with high electron cloud density, so that the sulfonic acid groups are easily complexed with chromium ions and lead ions in wastewater to form micro-flocculations and form precipitation through electrical neutralization with quaternary ammonium salt groups, thereby effectively removing heavy metal ions and achieving the effect of flocculation.

Description

A kind of sewage treatment flocculant and preparation method thereof

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a sewage treatment flocculant and a preparation method thereof.

Background Art

Flocculants can be divided into two categories: inorganic flocculants and organic flocculants. Inorganic flocculants include inorganic coagulants and inorganic polymer flocculants; organic flocculants include synthetic organic polymer flocculants, natural organic polymer flocculants and microbial flocculants. Flocculants are widely used in sewage treatment. With the development of industrialization, various domestic and industrial sewage are increasing, and discharge into the environment will eventually endanger human health. Therefore, how to avoid this phenomenon is the key to solving the problem.

Chitosan is a natural alkaline polysaccharide substance with excellent biological functions and chemical modification reaction activity. It is widely used in many fields. In terms of flocculants, chitosan is used as a cationic flocculant, mainly used to remove suspended particles and improve the recovery of liquid products. The present invention compounded chitosan with sulfonic acid-quaternary ammonium salt copolymer and bentonite-modified phenolic resin to prepare a flocculant that can efficiently treat heavy metal ions in water.

Summary of the invention

1. Technical issues to be resolved

In view of the deficiencies of the prior art, the present invention provides a sewage treatment flocculant and a preparation method thereof, which solves the problem of heavy metal ion pollution in water.

(II) Technical solution

To achieve the above object, the present invention provides the following technical solution: a sewage treatment flocculant, comprising the following weight components: 4-10 weight parts of sulfonic acid-quaternary ammonium salt copolymer, 8-12 weight parts of bentonite-modified phenolic resin, and 15-25 weight parts of chitosan;

The preparation method of the sulfonic acid-quaternary ammonium salt copolymer is:

S1. Add 5-8 parts by weight of hydroxylated bentonite and 2-5 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 90-110 ° C for 10-15h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite;

S2. Dissolve 4-7 parts by weight of allyltrimethylammonium chloride and 3-6 parts by weight of sodium 2-acrylamide-2-methylpropane sulfonate, add 5-10 parts by weight of olefinated bentonite into N,N-dimethylformamide solvent, dissolve them, then add 0.5-1 parts by weight of initiator, carry out polymerization reaction, react at 90-120°C for 10-15h, and obtain sulfonic acid-quaternary ammonium salt copolymer.

Preferably, the preparation method of the bentonite-modified phenolic resin is:

(1) adding 8-12 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 2-3% by mass sulfuric acid solution, stirring and reacting at 50-75° C. for 15-22 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, react at 30-40°C for 8-15h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 5-10 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir, then dropwise add 1-2 parts by weight of boron tribromide, react at -15°C to -10°C for 15-20 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) Add phenol-modified bentonite and formaldehyde into a stirrer, react at 70-90°C for 45-55 minutes, then add ethylenediamine dropwise, raise the temperature to 95-100°C, reflux for dehydration, and cool to room temperature to obtain bentonite-modified phenolic resin.

Preferably, the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst in (2) is 1.1-1.3:1:0.01-0.03.

Preferably, the stirring time in (3) is 10-20 min.

Preferably, the mass ratio of phenol-modified bentonite, formaldehyde and ethylenediamine in (4) is 1:1.1-1.2:0.4-0.8.

Preferably, the initiator in S2 is azobisisobutyronitrile.

Preferably, the preparation method of the sewage treatment flocculant is: adding sulfonic acid-quaternary ammonium salt copolymer, bentonite-modified phenolic resin and chitosan into a stirrer, stirring for 20-30 minutes, and obtaining the sewage treatment flocculant after stirring.

3. Beneficial technical effects

The invention provides a sewage treatment flocculant by adding sulfonic acid-quaternary ammonium salt copolymer, bentonite modified phenolic resin and chitosan into a stirrer and stirring the mixture.

The bentonite in the bentonite-modified phenolic resin has a large specific surface area and good adsorption capacity, and the cations between the montmorillonite layers can be well exchanged with the chromium ions and lead ions in the wastewater to achieve the effect of flocculation through adsorption; the phenolic resin has a high phenolic hydroxyl content and strong hydrophilicity, and has a good adsorption effect on the chromium ions and lead ions in the wastewater, and the coordination and hydrogen bonding of the amine groups in the phenolic resin make it have good adsorption energy for heavy metal ions, and synergistically achieve flocculation; the sulfonic acid group in the sulfonic acid-quaternary ammonium salt copolymer has a sulfur atom with a high electron cloud density, which makes it easy to complex with the chromium ions and lead ions in the wastewater to form tiny flocs, which are electrically neutralized with the quaternary ammonium salt group to form precipitation, effectively remove heavy metal ions, and achieve the effect of flocculation; and the sulfonic acid group in the sulfonic acid-quaternary ammonium salt copolymer, the phenolic hydroxyl group and the amino group in the bentonite-modified phenolic resin, and the amino group and the hydroxyl group in the chitosan form hydrogen bonds to form a cross-linked network, which can more effectively adsorb heavy metal ions in the wastewater to achieve the effect of flocculation.

DETAILED DESCRIPTION

γ-Glycidyloxypropyltrimethoxysilane modified bentonite was prepared according to the literature "Adsorption performance of tetraethylenepentamine grafted bentonite on acid red GR" (Chemical Industry Progress, Vol. 40, No. 5, 2021):

Add 2 g of bentonite to 100 mL of 7% hydrochloric acid solution, heat and reflux at 80 ° C for acidification, filter, wash with deionized water and dry to obtain acid-modified bentonite. Disperse 2 g of acid-modified bentonite in 150 mL of ethanol, add 8 g of γ-glycidyloxypropyltrimethoxysilane, stir and reflux at 90 ° C in a nitrogen atmosphere for 24 hours, filter, wash with ethanol and dry to obtain γ-glycidyloxypropyltrimethoxysilane-modified bentonite.

Example 1

(1) adding 8 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 2% sulfuric acid solution, stirring and reacting at 50° C. for 15 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, wherein the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst is 1.1:1:0.01, react at 30°C for 8h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 5 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir for 10 minutes, then dropwise add 1 part by weight of boron tribromide, react at -15°C for 15 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) adding phenol-modified bentonite and formaldehyde into a stirrer, reacting at 70° C. for 45 min, then adding ethylenediamine dropwise, wherein the mass ratio of phenol-modified bentonite, formaldehyde, and ethylenediamine is 1:1.1:0.4, heating to 95° C., reflux dehydration, and cooling to room temperature to obtain bentonite-modified phenolic resin;

(5) Add 5 parts by weight of hydroxylated bentonite and 2 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 90° C. for 10 h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite;

(6) 4 parts by weight of allyltrimethylammonium chloride and 3 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate are dissolved, and 5 parts by weight of olefinated bentonite are added into N,N-dimethylformamide solvent to dissolve, and then 0.5 parts by weight of azobisisobutyronitrile initiator is added to carry out polymerization reaction, and the reaction is carried out at 90° C. for 10 hours to obtain a sulfonic acid-quaternary ammonium salt copolymer;

(7) 4 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 8 parts by weight of bentonite-modified phenolic resin, and 15 parts by weight of chitosan were added into a stirrer and stirred for 20 minutes to obtain a wastewater treatment flocculant.

Example 2

(1) adding 12 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 3% sulfuric acid solution, stirring and reacting at 75° C. for 22 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, wherein the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst is 1.3:1:0.03, react at 40°C for 15h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 10 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir for 20 minutes, then dropwise add 1-2 parts by weight of boron tribromide, react at -10°C for 20 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) adding phenol-modified bentonite and formaldehyde into a stirrer, reacting at 90° C. for 55 min, then adding ethylenediamine dropwise, wherein the mass ratio of phenol-modified bentonite, formaldehyde, and ethylenediamine is 1:1.2:0.8, heating to 100° C., reflux dehydration, and cooling to room temperature to obtain bentonite-modified phenolic resin;

(5) Add 8 parts by weight of hydroxylated bentonite and 5 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 110° C. for 15 h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite;

(6) dissolving 7 parts by weight of allyltrimethylammonium chloride and 6 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate, adding 10 parts by weight of olefinated bentonite into N,N-dimethylformamide solvent, dissolving them, and then adding 1 part by weight of azobisisobutyronitrile initiator to carry out polymerization reaction at 120° C. for 15 hours to obtain a sulfonic acid-quaternary ammonium salt copolymer;

(7) Add 10 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 12 parts by weight of bentonite-modified phenolic resin, and 25 parts by weight of chitosan into a stirrer and stir for 30 minutes to obtain a wastewater treatment flocculant.

Example 3

(1) adding 10 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 2.5% sulfuric acid solution, stirring and reacting at 62.5° C. for 18.5 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, wherein the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst is 1.2:1:0.02, react at 35°C for 11.5h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 7.5 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir for 15 minutes, then dropwise add 1.5 parts by weight of boron tribromide, react at -12.5°C for 17.5 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) adding phenol-modified bentonite and formaldehyde into a stirrer, reacting at 80° C. for 50 min, then adding ethylenediamine dropwise, wherein the mass ratio of phenol-modified bentonite, formaldehyde, and ethylenediamine is 1:1.15:0.6, heating to 97.5° C., reflux dehydration, and cooling to room temperature to obtain bentonite-modified phenolic resin;

(5) Add 6.5 parts by weight of hydroxylated bentonite and 3.5 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 100° C. for 12.5 hours, and then perform vacuum distillation, filter and dry to obtain olefinated bentonite;

(6) 5.5 parts by weight of allyltrimethylammonium chloride and 4.5 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate were dissolved, and 7.5 parts by weight of olefinated bentonite was added into N,N-dimethylformamide solvent to dissolve, and then 0.75 parts by weight of azobisisobutyronitrile initiator was added to carry out polymerization reaction, and the reaction was carried out at 105° C. for 12.5 hours to obtain a sulfonic acid-quaternary ammonium salt copolymer;

(7) Add 7 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 10 parts by weight of bentonite-modified phenolic resin, and 20 parts by weight of chitosan into a stirrer and stir for 25 minutes to obtain a sewage treatment flocculant.

Example 4

(1) adding 8 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 2% sulfuric acid solution, stirring and reacting at 50° C. for 15 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, wherein the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst is 1.1:1:0.01, react at 30°C for 8h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 5 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir for 10 minutes, then dropwise add 1 part by weight of boron tribromide, react at -15°C for 15 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) adding phenol-modified bentonite and formaldehyde into a stirrer, reacting at 90° C. for 55 min, then adding ethylenediamine dropwise, wherein the mass ratio of phenol-modified bentonite, formaldehyde, and ethylenediamine is 1:1.2:0.8, heating to 100° C., reflux dehydration, and cooling to room temperature to obtain bentonite-modified phenolic resin;

(5) Add 8 parts by weight of hydroxylated bentonite and 5 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 110° C. for 15 h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite;

(6) 5.5 parts by weight of allyltrimethylammonium chloride and 4.5 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate were dissolved, and 7.5 parts by weight of olefinated bentonite was added into N,N-dimethylformamide solvent to dissolve, and then 0.75 parts by weight of azobisisobutyronitrile initiator was added to carry out polymerization reaction, and the reaction was carried out at 105° C. for 12.5 hours to obtain a sulfonic acid-quaternary ammonium salt copolymer;

(7) Add 7 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 10 parts by weight of bentonite-modified phenolic resin, and 20 parts by weight of chitosan into a stirrer and stir for 25 minutes to obtain a sewage treatment flocculant.

Example 5

(1) adding 12 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite to a 3% sulfuric acid solution, stirring and reacting at 75° C. for 22 hours, filtering, washing and drying after the reaction, to obtain hydroxylated bentonite;

(2) Add hydroxylated bentonite to 1,4-dioxane solvent, stir evenly, then continue to add p-methoxybenzoyl chloride and pyridine catalyst, wherein the mass ratio of hydroxylated bentonite, p-methoxybenzoyl chloride and pyridine catalyst is 1.3:1:0.03, react at 40°C for 15h, concentrate the solvent after the reaction, wash with acetone, and obtain an intermediate;

(3) Add 10 parts by weight of the intermediate to N,N-dimethylformamide solvent, stir for 20 minutes, then dropwise add 1-2 parts by weight of boron tribromide, react at -10°C for 20 hours, then continue to add methanol to terminate the reaction, pour the solution into ice water to precipitate, filter and wash, and recrystallize from ethyl acetate to obtain phenol-modified bentonite;

(4) adding phenol-modified bentonite and formaldehyde into a stirrer, reacting at 80° C. for 50 min, then adding ethylenediamine dropwise, wherein the mass ratio of phenol-modified bentonite, formaldehyde, and ethylenediamine is 1:1.15:0.6, heating to 97.5° C., reflux dehydration, and cooling to room temperature to obtain bentonite-modified phenolic resin;

(5) Add 6.5 parts by weight of hydroxylated bentonite and 3.5 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 100° C. for 12.5 hours, and then perform vacuum distillation, filter and dry to obtain olefinated bentonite;

(6) 4 parts by weight of allyltrimethylammonium chloride and 3 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate are dissolved, and 5 parts by weight of olefinated bentonite are added into N,N-dimethylformamide solvent to dissolve, and then 0.5 parts by weight of azobisisobutyronitrile initiator is added to carry out polymerization reaction, and the reaction is carried out at 90° C. for 10 hours to obtain a sulfonic acid-quaternary ammonium salt copolymer;

(7) 4 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 8 parts by weight of bentonite-modified phenolic resin, and 15 parts by weight of chitosan were added into a stirrer and stirred for 20 minutes to obtain a wastewater treatment flocculant.

Comparative Example 1

8 parts by weight of bentonite-modified phenolic resin and 15 parts by weight of chitosan were added into a stirrer and stirred for 20 minutes to obtain a sewage treatment flocculant.

Comparative Example 2

4 parts by weight of sulfonic acid-quaternary ammonium salt copolymer and 15 parts by weight of chitosan were added into a stirrer and stirred for 20 minutes. After stirring, a sewage treatment flocculant was obtained.

200 mL of wastewater was taken into a beaker. The initial concentrations of Cd ²⁺ and Pb ²⁺ in the wastewater were both 100 mg/L. Wastewater adsorbent was added to the wastewater. After ultrasonic dispersion for 5 minutes, the mixture was placed on a shaker for 12 hours. The supernatant was taken and the post-adsorption concentrations of Cd ²⁺ and Pb ²⁺ in the supernatant were determined by ICP. The removal rate of heavy metal ions w = (initial concentration - post-adsorption concentration) / initial concentration. The test results are shown in Table 1.

Table 1: Heavy metal ion removal rate test.

project Cd ²⁺ removal rate (%) Pb ²⁺ removal rate (%) Example 1 88.1 87.5 Example 2 92.3 91.7 Example 3 89.6 90.3 Example 4 78.5 89.6 Example 5 89.4 90.1 Comparative Example 1 52.1 52.4 Comparative Example 2 50.4 51.7

It can be seen from Table 1 that Examples 1-5 of the present invention have better removal effects on heavy metal ions than Comparative Examples 1-2, indicating that the flocculation effect is better.

The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims (6)

1. The sewage treatment flocculant is characterized by comprising the following components in parts by weight: 4-10 parts by weight of sulfonic acid-quaternary ammonium salt copolymer, 8-12 parts by weight of bentonite modified phenolic resin and 15-25 parts by weight of chitosan;

The preparation method of the sulfonic acid-quaternary ammonium salt copolymer comprises the following steps:

S1, adding 5-8 parts by weight of hydroxylated bentonite and 2-5 parts by weight of 2-chloro-4, 6-diallyl triazine into an N, N-dimethylformamide solvent, stirring and mixing, reacting for 10-15 hours at 90-110 ℃, distilling under reduced pressure after the completion, filtering and drying to obtain alkenylated bentonite;

S2, dissolving 4-7 parts by weight of allyl trimethyl ammonium chloride, 3-6 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid sodium salt, adding 5-10 parts by weight of alkenylation bentonite into an N, N-dimethylformamide solvent, dissolving, then adding 0.5-1 part by weight of initiator, carrying out polymerization reaction, and reacting for 10-15 hours at 90-120 ℃ to obtain a sulfonic acid-quaternary ammonium salt copolymer;

the preparation method of the bentonite modified phenolic resin comprises the following steps:

(1) Adding 8-12 parts by weight of gamma-glycidoxypropyl trimethoxy silane modified bentonite into 2-3% sulfuric acid solution, stirring at 50-75 ℃ for reaction for 15-22 hours, filtering, washing and drying after finishing to obtain hydroxylated bentonite;

(2) Adding the hydroxylated bentonite into a1, 4-dioxane solvent, uniformly stirring, then continuously adding p-methoxybenzoyl chloride and a pyridine catalyst, reacting for 8-15h at 30-40 ℃, concentrating the solvent after the reaction, and washing with acetone to obtain an intermediate;

(3) Adding 5-10 parts by weight of an intermediate into an N, N-dimethylformamide solvent, stirring, then dropwise adding 1-2 parts by weight of boron tribromide, reacting for 15-20 hours at the temperature of minus 15 ℃ to minus 10 ℃, then continuously adding methanol to terminate the reaction, pouring the solution into ice water to separate out a precipitate, filtering and washing, and recrystallizing ethyl acetate to obtain phenol modified bentonite;

(4) Adding phenol modified bentonite and formaldehyde into a stirrer, reacting for 45-55min at 70-90 ℃, then dripping ethylenediamine, heating to 95-100 ℃, refluxing for dehydration, and cooling to room temperature to obtain bentonite modified phenolic resin.

2. The flocculant for sewage treatment according to claim 1, wherein the mass ratio of the hydroxylated bentonite, the p-methoxybenzoyl chloride and the pyridine catalyst in (2) is 1.1-1.3:1:0.01-0.03.

3. The flocculant for sewage treatment according to claim 1, wherein the stirring time in (3) is 10 to 20 minutes.

4. The flocculant for sewage treatment according to claim 1, wherein the mass ratio of the phenol modified bentonite, formaldehyde and ethylenediamine in (4) is 1:1.1-1.2:0.4-0.8.

5. The flocculant for sewage treatment according to claim 1, wherein the initiator in S2 is azobisisobutyronitrile.

6. A method for preparing a sewage treatment flocculant according to any one of claims 1 to 5, wherein the sewage treatment flocculant is prepared by: adding the sulfonic acid-quaternary ammonium salt copolymer, bentonite modified phenolic resin and chitosan into a stirrer, stirring for 20-30min, and obtaining the sewage treatment flocculant after the completion of the stirring.