Preparation method of emulsion polyacrylamide for papermaking wastewater treatment

Abstract

The invention relates to the technical field of papermaking wastewater treatment, in particular to a method for preparing an emulsion type polyacrylamide for papermaking wastewater treatment, comprising the following steps: S1. placing 10-12 parts by mass of acrylamide, 2-3 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05-0.2 parts of urea, 0.05-0.2 parts of an inorganic flocculant, 0.05-0.3 parts of a crosslinking agent, 0.01-0.1 parts of a chelating agent, 0.01-0.1 parts of a chain transfer agent, and 25-40 parts of deionized water in a beaker and fully dissolving them to obtain a mixed solution; S2. preparing an aqueous phase and an oil phase of a polymerization reaction system; S3. preparing a transparent emulsion polymerization system; S4. pouring the emulsion polymerization system into a three-necked flask, and introducing nitrogen; and S5. dropping an initiator into the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain the emulsion type polyacrylamide for papermaking wastewater treatment. The invention not only has excellent biodegradability but is also renewable, meets the requirements of sustainable development, and is suitable for a variety of industrial applications, especially in fields with high requirements on environmental impact.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking wastewater treatment, in particular to a method for preparing an emulsion-type polyacrylamide for papermaking wastewater treatment. Background Art

[0002] Papermaking wastewater is one of the main sources of industrial water pollutants in my country. Due to the addition of a large amount of chemicals in the papermaking process, papermaking wastewater usually contains extremely fine suspended powders, soluble solids, inorganic and organic particles, metal ion compounds and other impurities. In the deep treatment of papermaking wastewater, the methods generally used include: physical treatment, chemical treatment, biological treatment and the combination of the above methods. Among them, flocculation sedimentation and advanced oxidation methods represented by Fenton oxidation have better application effects, but Fenton oxidation has a high treatment cost and harsh application conditions. Flocculation sedimentation is the most widely used in the field of papermaking wastewater treatment.

[0003] At present, the most widely used flocculants are divided into organic flocculants and inorganic flocculants. The commonly used organic flocculant in papermaking wastewater treatment is polyacrylamide, and the commonly used inorganic flocculants are inorganic metal salts such as iron and aluminum. However, traditional flocculants have deficiencies in molecular form, degree of polymerization and corresponding flocculation effect. It is difficult to meet the increasingly stringent emission standards by using polyacrylamide or inorganic flocculants alone to treat papermaking wastewater. The present invention introduces a small amount of inorganic flocculant in the preparation process of polyacrylamide to prepare a composite flocculant, which can be more effectively applied to the field of papermaking wastewater treatment. Traditional papermaking additives can no longer meet their high anion and cation requirements and their requirements for small additive particle size and large specific surface area. The addition amount is large and the effect is not good, and the cost of recycling sediment is high. Synthesizing an emulsion polyacrylamide suitable for recycling sediment in papermaking wastewater, solving the problem of reduced papermaking performance caused by fiber reuse in sediment is of great significance for realizing the resource utilization of pollutants in papermaking wastewater. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater comprises the following steps:

[0007] S1. 10-12 parts by mass of acrylamide, 2-3 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05-0.2 parts of urea, 0.05-0.2 parts of inorganic flocculant, 0.05-0.3 parts of cross-linking agent, 0.01-0.1 parts of chelating agent, 0.01-0.1 parts of chain transfer agent, and 25-40 parts of deionized water are placed in a beaker and fully dissolved to obtain a mixed solution;

[0008] S2. The pH value of the mixture was adjusted to 5.0-5.5 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 10-20 parts of an oil-soluble solvent and 5-10 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0009] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0010] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2-3h under stirring at 350-400r / min;

[0011] S5. Using a syringe pump, slowly add a 0.8-1% initiator to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0012] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0013] S101. 30-35 parts of vegetable oil are heated to 60-65°C and mixed with 1-3 parts of immobilized papain to obtain an esterified mixture;

[0014] S102. Dissolve 1-3 parts of chitosan in 10-20 parts of deionized water to obtain a polysaccharide solution;

[0015] S103. The esterified mixture, the polysaccharide solution and 5-8 parts of the modified solution are mixed, the pH value is controlled to be 6-7, the temperature is 40-50 ° C, and a preliminary emulsifier is obtained;

[0016] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0017] Preferably, the preparation of the modified liquid comprises the following steps:

[0018] S201. 2-5 parts of acetone solution, 1-3 parts of soda ash and 10-15 parts of deionized water are added to a beaker and stirred at a temperature of 30-40 ° C. The reaction time is 5-10 min to obtain a preliminary mixed solution;

[0019] S202. Add 0.5-2 parts of sodium hypochlorite solution and 10-15 parts of sodium sulfate to the preliminary mixed solution and stir to obtain a modified solution.

[0020] Preferably, the stirring speed in step S201 is 300-500 r / min.

[0021] Preferably, the stirring speed in step S202 is 400-550 r / min.

[0022] Preferably, the crosslinking agent is selected from one or more of divinylbenzene, pentaerythritol triacrylate, and dimethyldiallylammonium chloride.

[0023] Preferably, the chelating agent is selected from one or more of diethylenetriaminepentaacetic acid pentasodium and diethylenetriaminepenta-methylenephosphonic acid sodium.

[0024] Preferably, the chain transfer agent is selected from one or more of sodium hypophosphite, sodium formate and isopropanol.

[0025] Preferably, the oil-soluble solvent is selected from one or more of kerosene, white oil and diesel.

[0026] Preferably, the initiator is selected from potassium persulfate, ammonium persulfate, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride.

[0027] Preferably, the inorganic flocculant is selected from one or more of ferric chloride, aluminum sulfate, and polyferric sulfate.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The modified emulsifier prepared by the present invention not only has excellent biodegradability, but is also renewable, meets the requirements of sustainable development, and is suitable for a variety of industrial applications, especially in fields with high requirements on environmental impact.

[0030] 2. The modified liquid in the present invention undergoes an oxidation reaction with the colored organic matter in the wastewater, destroying its chromophore group, causing the color of the wastewater to gradually fade, thereby achieving the effect of removing chromaticity. It can also improve the technical effect of the modified emulsifier in promoting the coagulation and precipitation of fine particles and promoting oil-water separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The process flow chart of the emulsion polyacrylamide for treating papermaking wastewater of the present invention is shown in FIG. DETAILED DESCRIPTION

[0032] The present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] See also Figure 1 , the present invention provides a technical solution:

[0034] Example 1

[0035] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0036] S1. 10 parts by mass of acrylamide, 2 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05 parts of urea, 0.05 parts of inorganic flocculant, 0.05 parts of cross-linking agent, 0.01 parts of chelating agent, 0.01 parts of chain transfer agent, and 25 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0037] S2. The pH value of the mixture was adjusted to 5.0 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 10 parts of an oil-soluble solvent and 5 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0038] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0039] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2h under stirring at 350r / min;

[0040] S5. Using a syringe pump, slowly add a 0.8% initiator by mass concentration to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0041] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0042] S101. 30 parts of vegetable oil are heated to 60°C and mixed with 1 part of immobilized papain to obtain an esterified mixture;

[0043] S102. Dissolve 1-3 parts of chitosan in 10 parts of deionized water to obtain a polysaccharide solution;

[0044] S103. The esterified mixture, the polysaccharide solution and 5 parts of the modified solution were mixed, the pH value was controlled to be 6, the temperature was 40°C, and a preliminary emulsifier was obtained;

[0045] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0046] The preparation of the modified solution comprises the following steps:

[0047] S201. 2 parts of acetone solution, 1 part of soda ash and 10 parts of deionized water were added to a beaker and stirred at a stirring speed of 300 r / min, a temperature of 30° C., and a reaction time of 5 min to obtain a preliminary mixed solution;

[0048] S202. Add 0.5 parts of sodium hypochlorite solution and 10 parts of sodium sulfate to the preliminary mixed solution and stir at a stirring speed of 400 r / min to obtain a modified solution.

[0049] Example 2

[0050] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0051] S1. 12 parts by mass of acrylamide, 3 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.2 parts of urea, 0.2 parts of an inorganic flocculant, 0.3 parts of a cross-linking agent, 0.1 parts of a chelating agent, 0.1 parts of a chain transfer agent, and 40 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0052] S2. The pH value of the mixture was adjusted to 5.5 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 20 parts of an oil-soluble solvent and 10 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0053] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0054] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2-3h under stirring at 400r / min;

[0055] S5 uses a syringe pump to slowly drop an initiator with a mass concentration of 1% into the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0056] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0057] S101. 35 parts of vegetable oil are heated to 65°C and mixed with 3 parts of immobilized papain to obtain an esterified mixture;

[0058] S102. Dissolve 3 parts of chitosan in 20 parts of deionized water to obtain a polysaccharide solution;

[0059] S103. The esterified mixture, the polysaccharide solution and 8 parts of the modified solution were mixed, the pH value was controlled to 7, the temperature was 50°C, and a preliminary emulsifier was obtained;

[0060] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0061] The preparation of the modified solution comprises the following steps:

[0062] S201. 5 parts of acetone solution, 3 parts of soda ash and 15 parts of deionized water were added to a beaker and stirred at a stirring speed of 500 r / min, a temperature of 40 ° C, and a reaction time of 10 min to obtain a preliminary mixed solution;

[0063] S202. Add 2 parts of sodium hypochlorite solution and 15 parts of sodium sulfate to the preliminary mixed solution and stir at a stirring speed of 550 r / min to obtain a modified solution.

[0064] Example 3

[0065] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0066] S1. 11 parts by mass of acrylamide, 2.5 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.1 parts of urea, 0.1 parts of inorganic flocculant, 0.1 parts of cross-linking agent, 0.05 parts of chelating agent, 0.05 parts of chain transfer agent, and 30 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0067] S2. The pH value of the mixture was adjusted to 5.2 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 13 parts of an oil-soluble solvent and 7 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0068] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0069] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced at 2.5 under stirring at 370 r / min;

[0070] S5. Using a syringe pump, slowly add a 0.9% initiator by mass concentration to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0071] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0072] S101. 32 parts of vegetable oil are heated to 62° C. and mixed with 2 parts of immobilized papain to obtain an esterified mixture;

[0073] S102. Dissolve 2 parts of chitosan in 13 parts of deionized water to obtain a polysaccharide solution;

[0074] S103. The esterified mixture, the polysaccharide solution and 6 parts of the modified solution were mixed, the pH value was controlled to be 6.5, the temperature was 44°C, and a preliminary emulsifier was obtained;

[0075] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0076] The preparation of the modified solution comprises the following steps:

[0077] S201. 3 parts of acetone solution, 2 parts of soda ash and 12 parts of deionized water were added to a beaker and stirred at a stirring speed of 400 r / min, a temperature of 34 ° C, and a reaction time of 6 min to obtain a preliminary mixed solution;

[0078] S202. Add 1 part of sodium hypochlorite solution and 12 parts of sodium sulfate to the preliminary mixed solution and stir at a stirring speed of 450 r / min to obtain a modified solution.

[0079] Example 4

[0080] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0081] S1. 11.5 parts by mass of acrylamide, 2.7 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.15 parts of urea, 0.15 parts of an inorganic flocculant, 0.2 parts of a cross-linking agent, 0.09 parts of a chelating agent, 0.09 parts of a chain transfer agent, and 35 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0082] S2. The pH value of the mixture was adjusted to 5.4 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 18 parts of an oil-soluble solvent and 9 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0083] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0084] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2.6 h at 390 r / min with stirring;

[0085] S5. Using a syringe pump, slowly add a 1% initiator by mass concentration to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0086] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0087] S101. 34 parts of vegetable oil are heated to 64° C. and mixed with 2.8 parts of immobilized papain to obtain an esterified mixture;

[0088] S102. Dissolve 2.5 parts of chitosan in 18 parts of deionized water to obtain a polysaccharide solution;

[0089] S103. The esterified mixture, the polysaccharide solution and 7 parts of the modified solution were mixed, the pH value was controlled to be 6.8, the temperature was 49° C., and a preliminary emulsifier was obtained;

[0090] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0091] The preparation of the modified solution comprises the following steps:

[0092] S201. 4 parts of acetone solution, 2.5 parts of soda ash and 14 parts of deionized water were added to a beaker and stirred at a stirring speed of 450 r / min, a temperature of 37 ° C, and a reaction time of 7 min to obtain a preliminary mixed solution;

[0093] S202. Add 1.5 parts of sodium hypochlorite solution and 14 parts of sodium sulfate to the preliminary mixed solution and stir at a stirring speed of 500 r / min to obtain a modified solution.

[0094] Comparative Example 1

[0095] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0096] S1. 10 parts by mass of acrylamide, 2 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05 parts of urea, 0.05 parts of inorganic flocculant, 0.05 parts of cross-linking agent, 0.01 parts of chelating agent, 0.01 parts of chain transfer agent, and 25 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0097] S2. The pH value of the mixture was adjusted to 5.0 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 10 parts of an oil-soluble solvent and 5 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0098] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0099] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2h under stirring at 350r / min;

[0100] S5. Using a syringe pump, slowly add a 0.8% initiator by mass concentration to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment;

[0101] Wherein, the preparation of the modified emulsifier comprises the following steps:

[0102] S101. 30 parts of vegetable oil are heated to 60°C and mixed with 1 part of immobilized papain to obtain an esterified mixture;

[0103] S102. Dissolve 1-3 parts of chitosan in 10 parts of deionized water to obtain a polysaccharide solution;

[0104] S103. The esterified mixture and the polysaccharide solution are mixed, the pH value is controlled to be 6, the temperature is 40° C., and a preliminary emulsifier is obtained;

[0105] S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

[0106] Comparative Example 2

[0107] A preparation method of emulsion polyacrylamide for papermaking wastewater treatment:

[0108] S1. 10 parts by mass of acrylamide, 2 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05 parts of urea, 0.05 parts of inorganic flocculant, 0.05 parts of cross-linking agent, 0.01 parts of chelating agent, 0.01 parts of chain transfer agent, and 25 parts of deionized water were placed in a beaker and fully dissolved to obtain a mixed solution;

[0109] S2. The pH value of the mixture was adjusted to 5.0 with phosphoric acid as the aqueous phase of the polymerization reaction system, 10 parts of an oil-soluble solvent and 5 parts of sodium dodecyl sulfate were weighed and mixed on a magnetic stirrer as the oil phase of the polymerization reaction system;

[0110] S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system;

[0111] S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2h under stirring at 350r / min;

[0112] S5. Use a syringe pump to slowly add an initiator with a mass concentration of 0.8% into the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment.

[0113] Performance Test:

[0114] The emulsion polyacrylamide prepared in Examples 1-4 and Comparative Examples 1-2 was used for the treatment of papermaking wastewater. The papermaking wastewater samples were taken from a paper mill in Anhui. The experiment was carried out simultaneously in 6 500ml beakers using a variable speed agitator. The papermaking wastewater and tap water were mixed in a mass ratio of 1:1. Then 400ml of the mixed papermaking wastewater was measured in 500ml beakers. 0.5g of the emulsion polyacrylamide prepared in Examples 1 to 6 was weighed and added to the beakers. The mixture was stirred at 400 rpm for 25 minutes to fully disperse the flocculant in the wastewater. The speed was then reduced to 200 rpm and stirring was continued for 5 minutes. After standing for 30 minutes, the supernatant 3cm away from the liquid surface was taken to analyze the water quality. SS was determined by the national standard method, and COD was determined by the potassium dichromate method. Cr , the color was measured by the dilution multiple method. The biodegradation rate after 30 days was measured by the standard GB / T 19276.1-2003 method for determining the ultimate aerobic biodegradability of materials in aqueous culture medium, biodegradation rate = (theoretical maximum oxygen demand (mg / L) / oxygen consumption (mg / L)) × 100%. The measurement results are shown in Table 1 below:

[0115] Table 1

[0116]

[0117]

[0118] Comparative Examples 1-2 are compared with Example 1. Compared with Example 1, Comparative Example 1 omits the addition of the modified liquid. Compared with Example 1, Comparative Example 2 replaces the modified emulsifier with an emulsifier commonly used in this field. Cr The removal rate, chroma removal rate and biodegradation rate are far lower than those of Examples 1 to 4. The present invention can effectively achieve the purpose of papermaking wastewater treatment, and the prepared modified emulsifier not only has excellent biodegradability, but is also renewable, meets the requirements of sustainable development, and is suitable for a variety of industrial applications, especially in areas with high environmental impact requirements, and can also achieve the effect of effectively removing chroma.

[0119] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater, characterized in that: The following steps are involved: S1. 10-12 parts by mass of acrylamide, 2-3 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.05-0.2 parts of urea, 0.05-0.2 parts of inorganic flocculant, 0.05-0.3 parts of cross-linking agent, 0.01-0.1 parts of chelating agent, 0.01-0.1 parts of chain transfer agent, and 25-40 parts of deionized water are placed in a beaker and fully dissolved to obtain a mixed solution; S2. The pH value of the mixture was adjusted to 5.0-5.5 with phosphoric acid, as the aqueous phase of the polymerization reaction system, 10-20 parts of an oil-soluble solvent and 5-10 parts of a modified emulsifier were weighed and mixed evenly on a magnetic stirrer as the oil phase of the polymerization reaction system; S3. Slowly pour the aqueous phase into the oil phase and continue stirring to prepare a transparent emulsion polymerization system; S4. The emulsion polymerization system prepared in S3 was poured into a three-necked flask and nitrogen was introduced for 2-3h under stirring at 350-400r / min; S5. Using a syringe pump, slowly add a 0.8-1% initiator to the emulsion polymerization system to initiate a polymerization reaction until the reaction is completed to obtain an emulsion polyacrylamide for papermaking wastewater treatment; Wherein, the preparation of the modified emulsifier comprises the following steps: S101. 30-35 parts of vegetable oil are heated to 60-65°C and mixed with 1-3 parts of immobilized papain to obtain an esterified mixture; S102. Dissolve 1-3 parts of chitosan in 10-20 parts of deionized water to obtain a polysaccharide solution; S103. The esterified mixture, the polysaccharide solution and 5-8 parts of the modified solution are mixed, the pH value is controlled to be 6-7, the temperature is 40-50 ° C, and a preliminary emulsifier is obtained; S104. Centrifuge and filter the preliminary emulsifier to remove unreacted oil and polysaccharide to obtain a modified emulsifier.

2. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The preparation of the modified solution comprises the following steps: S201. 2-5 parts of acetone solution, 1-3 parts of soda ash and 10-15 parts of deionized water are added to a beaker and stirred at a temperature of 30-40 ° C. The reaction time is 5-10 min to obtain a preliminary mixed solution; S202. Add 0.5-2 parts of sodium hypochlorite solution and 10-15 parts of sodium sulfate to the preliminary mixed solution and stir to obtain a modified solution.

3. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 2, characterized in that: In step S201, the stirring speed is 300-500 r / min.

4. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 2, characterized in that: In step S202, the stirring speed is 400-550 r / min.

5. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The crosslinking agent is selected from one or more of divinylbenzene, pentaerythritol triacrylate, and dimethyldiallylammonium chloride.

6. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The chelating agent is selected from one or more of diethylenetriamine pentaacetic acid pentasodium and diethylenetriamine pentasodium methylenephosphonate.

7. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The chain transfer agent is selected from one or more of sodium hypophosphite, sodium formate and isopropanol.

8. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The oil-soluble solvent is selected from one or more of kerosene, white oil and diesel.

9. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The initiator is selected from potassium persulfate, ammonium persulfate, azobisisobutyronitrile and azobisisobutyramidine hydrochloride.

10. The method for preparing an emulsion-type polyacrylamide for treating papermaking wastewater according to claim 1, characterized in that: The inorganic flocculant is selected from one or more of ferric chloride, aluminum sulfate and polyferric sulfate.

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