Preparation method of amphiphilic papermaking pulp residue-based organic polymer flocculant

Abstract

The present invention discloses a method for preparing an amphiphilic paper pulp residue-based organic polymer flocculant, and belongs to the technical field of solid waste resource utilization and water treatment agents. The present invention heats a lignin solution to a certain temperature under weak alkaline conditions, uses potassium persulfate as an initiator and disodium ethylenediaminetetraacetic acid as a chelating agent, and stirs and activates the solution under nitrogen protection, then adds a mixed solution of methacryloyloxyethyltrimethylammonium chloride solution and vinyl acetate and potassium persulfate to the reactor, and stirs and reacts for a sufficient time; finally, the product is precipitated in an acetone and dichloromethane solution, and a highly efficient paper pulp residue-based organic polymer flocculant product is obtained after filtering, washing, and drying. When the obtained flocculant is used to treat simulated surface water containing antibiotics, the turbidity removal rate reaches 90% when the dosage is 10 mg / L, and the humic acid (UV 254 ) removal rate is close to 85%, and the tetracycline removal rate is close to 80%.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization and water treatment agents, and in particular relates to a method for preparing an amphiphilic papermaking pulp residue-based organic polymer flocculant. Background Art

[0002] At present, new antibiotic pollutants are frequently detected in surface water. The concentration of antibiotics in surface water is usually very low, and they are often adsorbed on the surface of natural organic matter (NOM) or suspended particles through microinterface reactions to form complex composite pollutants. Therefore, how to economically and efficiently remove trace antibiotics and their composite pollutants in water has become a key issue that needs to be solved urgently.

[0003] Coagulation has been widely used in water treatment due to its advantages of low investment and operating costs, simple operation and management. However, traditional inorganic coagulants have poor removal effects on antibiotics in water. From a theoretical analysis, based on the chemical structure and characteristics of organic pollutants, the interaction between flocculants and antibiotic pollutants can be strengthened by regulating the functional groups and molecular structures of organic polymer flocculants, thereby achieving efficient removal of antibiotic pollutants in water. At present, there are two major categories of organic polymer flocculants, one is artificially synthesized organic polymers, and the other is a new type of high-efficiency organic polymer flocculant obtained by modifying biomass as raw materials. Today, with the increasing awareness of environmental protection, biomass organic polymer flocculants have the advantages of low toxicity, wide source of raw materials, easy biodegradability, and low price. The flocculants obtained by modifying biomass, especially industrial and agricultural waste as raw materials (etherification, esterification, sulfonation, graft copolymerization, etc.) can not only realize the comprehensive utilization of waste resources, but also reduce the preparation and application costs of flocculants. The use of biomass-based flocculants to treat composite surface wastewater containing antibiotics has very important practical significance and application value.

[0004] At present, most paper mills use wood pulp as the main raw material for papermaking, and a large amount of pulp residue is generated during the papermaking process. Pulp residue is the waste residue generated in the process of papermaking pulping and is a waste of the papermaking industry. So far, how to achieve high-value treatment, disposal and comprehensive utilization of papermaking pulp residue has always been a difficult problem that has plagued the development of papermaking enterprises. The commonly used method for treating pulp residue is secondary recovery and cooking, but its utilization rate is low and it is impossible to achieve the goal of zero discharge of papermaking pulp residue. Wood pulp papermaking pulp residue has a rich biomass content, with a cellulose, lignin and hemicellulose content of up to about 70%, and an extremely low (trace) heavy metal content, making it a valuable biomass resource. Therefore, using the organic matter in papermaking pulp residue as raw material, chemically modifying it to prepare a new biomass organic polymer flocculant and using it to remove antibiotics in water bodies has important theoretical and practical significance for realizing the comprehensive utilization of papermaking pulp residue resources, and has application prospects.

[0005] At present, there are also reports on the use of biomass to prepare flocculants. Most of them use finished lignin, chitosan, etc. as raw materials. The products obtained generally have a small molecular weight and weak hydrophobic effect, which makes it difficult to form a strong interaction with antibiotics. At the same time, the concentration of treated antibiotics is too high, which does not conform to the actual water conditions and cannot meet the actual sewage treatment requirements. Therefore, it is of great significance to develop high molecular weight organic flocculants with high interaction with antibiotics to meet market demand. Summary of the invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention proposes a method for preparing an amphiphilic papermaking pulp residue-based organic polymer flocculant, which has high charge density, large molecular weight, and a branched network structure, and can effectively remove antibiotics and organic matter in sewage.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] Technical purpose 1: A method for preparing an amphiphilic papermaking pulp residue-based organic polymer flocculant, comprising the following steps:

[0009] (1) adding papermaking pulp residue to deionized water, then adding sodium hydroxide, boiling in an oil bath at 130° C., centrifuging to obtain the supernatant, and adjusting the pH to 7-9, preferably to 7.5-8.5, and more preferably to 8, with a 0.1 mol / L HCl solution;

[0010] (2) heating the pH-adjusted supernatant to 70° C. under a nitrogen atmosphere and stirring for 15-30 min, adding potassium persulfate to the system and stirring for 5 min, then adding disodium ethylenediaminetetraacetate and stirring for 10 min, and finally adding vinyl acetate solution, methacryloyloxyethyltrimethylammonium chloride solution and potassium persulfate, stirring for 3.5-5.5 h;

[0011] (3) After the reaction is completed, the mixture is cooled to room temperature, and the reaction product is precipitated with acetone and dichloromethane. The reaction product is filtered, and the filter residue is washed with pure water and then freeze-dried in vacuum to obtain an amphiphilic papermaking pulp residue-based organic polymer flocculant.

[0012] Furthermore, the ratio of the papermaking pulp residue to the deionized water is 1 g: 100 mL;

[0013] The mass ratio of the papermaking pulp residue to the sodium hydroxide is 2:(0.5-2), preferably 2:1;

[0014] The mass ratio of the papermaking pulp residue to the total mass of potassium persulfate is 2:(0.025-0.1), preferably 2:0.05;

[0015] The mass ratio of the papermaking pulp residue to disodium ethylenediaminetetraacetate is 2:(0-0.1), preferably 2:0.05. Disodium ethylenediaminetetraacetate as a chelating agent mainly functions to chelate metal ions, and has little effect on charge density.

[0016] The papermaking pulp residue, vinyl acetate solution and methacryloyloxyethyl trimethyl ammonium chloride solution are used in a ratio of 2 g: (1-4) mL: (2.5-10) mL, preferably 2 g: 1 mL: 5 mL. The vinyl acetate solution and methacryloyloxyethyl trimethyl ammonium chloride solution exist in the form of a mixed solution, and the volume ratio is (1-4) mL: (2.5-10) mL, preferably 1:5.

[0017] Furthermore, the pH value of the papermaking pulp residue is 7.82, the ash content is 25wt%, the organic matter content is 70wt%, the lignin content is 20.5wt%, the cellulose content is 33.5wt%, and the residue rate is 78wt%.

[0018] Technical purpose 2: An amphiphilic paper pulp residue-based organic polymer flocculant prepared by the above preparation method, wherein the flocculant has a charge density of 1440-1460ueq / L and a weight average molecular weight of 120kDa.

[0019] Technical purpose three: An application of the amphiphilic paper pulp residue-based organic polymer flocculant in the simultaneous removal of turbidity, organic matter and antibiotics in wastewater.

[0020] Furthermore, the organic matter is humic acid, and the antibiotic is tetracycline. The dosage of the amphiphilic papermaking pulp residue-based organic polymer flocculant in the wastewater is 7.5-12.5 mg / L, preferably 10 mg / L.

[0021] Principle of the invention: The invention utilizes hemicellulose and lignin in papermaking pulp residue, and methacryloyloxyethyl trimethyl ammonium chloride and vinyl acetate monomers under the action of an initiator to undergo graft copolymerization reaction to generate a macromolecular copolymer with a branched structure. The obtained product has a high charge density, a large molecular weight, and a network structure. The charge density is 1440-1460ueq / L, and the weight average molecular weight can reach 120kDa. The obtained flocculant has both hydrophobic groups and hydrophilic groups, and has strong interactions with antibiotics and coexisting organic matter. The treatment capacity for composite sewage containing antibiotics is higher than that of traditional inorganic flocculants. It has the advantages of high flocculation efficiency and easy purification, and is suitable for the field of wastewater treatment.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] 1. The flocculant product obtained by the present invention has a larger hydrophobic segment, better binding efficiency with antibiotics, and a larger floc particle size. The adsorption and bridging effect on tiny flocs is better than that of traditional flocculants. At the same time, the flocculant has a higher charge density, stronger adsorption and electrical neutralization ability, and better removal effect on anionic organic matter in water.

[0024] 2. The flocculation efficiency of the flocculant product obtained by the present invention is better than that of the existing lignin-based flocculant products. When the dosage is about 10 mg / L, it can achieve a turbidity removal rate of nearly 90%, an organic matter removal rate of about 85% and an antibiotic removal rate of nearly 80%.

[0025] 3. The preparation method of the present invention has a simple production process, few by-products, and few equipment requirements, and is easy to realize industrial production. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0028] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0029] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0030] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] The "room temperature" mentioned in the present invention is 25±2°C unless otherwise specified.

[0032] The raw materials used in the following examples of the present invention are all commercially available.

[0033] On the one hand, the present invention lays a theoretical foundation for the treatment of composite surface sewage containing antibiotics by high-efficiency organic polymer flocculants, and on the other hand, it can realize the comprehensive resource utilization of papermaking pulp residue, which has important theoretical and practical significance and has great prospects for promotion and application.

[0034] The papermaking pulp residue used in the following examples of the present invention is the papermaking pulp residue produced in the dry alkaline papermaking production process, with pH = 7.82, ash content of 25wt%, organic matter content of 70wt%, lignin content of 20.5wt%, cellulose content of 33.5wt%, and residue rate of 78wt%.

[0035] Preparation of simulated surface water containing antibiotics:

[0036] (1) Weigh 1 g of humic acid and 0.4 g of sodium hydroxide and dissolve them in deionized water to make a volume of 1 L for later use;

[0037] (2) Weigh 5 g of kaolin and dissolve it in 1 L of deionized water. Take the supernatant for later use;

[0038] (3) Weigh 100 mg of tetracycline and dissolve it in 1 L of deionized water for later use;

[0039] (4) Take 10 mL of the above-mentioned humic acid reserve solution and 10 mL of tetracycline reserve solution and dissolve them in 1 L of tap water. Adjust the turbidity with kaolin reserve solution to obtain the experimental water sample.

[0040] Zeta potential, turbidity, UV of experimental water samples 254 They were -20±1mv, 15±0.5, 0.263±0.002 respectively, and the tetracycline concentration was 1mg / L.

[0041] The final effluent treatment effect of simulated surface water containing tetracycline was measured by turbidity removal rate (%), UV 254 Removal rate (%), tetracycline removal rate (%) are comprehensively expressed. 254 Removal rate refers to the humic acid removal rate.

[0042] The following examples serve as further illustrations of the technical solutions of the present invention.

[0043] Example 1

[0044] Preparation of an amphiphilic papermaking pulp residue-based organic polymer flocculant:

[0045] (1) Weigh 2 g of papermaking pulp residue and add it to 200 mL of deionized water, add 1 g of sodium hydroxide, boil it in an oil bath at 130° C. for 1 h, centrifuge and take the supernatant, and adjust the pH to 8 with a 0.1 mol / L HCl solution;

[0046] (2) The reactor was placed in a 70°C water bath, and nitrogen was continuously introduced and stirred for 15 minutes to remove air from the supernatant; while nitrogen was introduced, 30 mg of potassium persulfate was added to the system and stirred for 5 minutes, and then 30 mg of disodium ethylenediaminetetraacetate was added and stirred for 10 minutes, and finally 1 mL of vinyl acetate solution and 5 mL of 75% methacryloyloxyethyltrimethylammonium chloride solution were added dropwise to the system, followed by adding 20 mg of potassium persulfate and stirring for 4.5 hours;

[0047] (3) After the reaction is completed, the mixture is cooled to room temperature, and 2.5 times the volume of the reaction product of acetone and 1 times the volume of dichloromethane are added to the reaction product in sequence to precipitate the reaction product. The reaction product is filtered, and the filter residue is taken, washed with pure water, and then vacuum-freeze-dried to obtain an amphiphilic papermaking pulp residue-based organic polymer flocculant.

[0048] Application Example 1

[0049] Taking the amount of disodium ethylenediaminetetraacetate added as a variable, the amount of disodium ethylenediaminetetraacetate added in Example 1 was changed to 0 mg, 50 mg, and 100 mg, respectively, to obtain different flocculants a1, b1, and c1, respectively. The charge density of a1, b1, and c1 was tested, and the results are shown in Table 1. A1, b1, and c1 were used to treat simulated surface water containing tetracycline at different dosages, and the treatment results are shown in Table 2.

[0050] Table 1 Charge density (ueq / L)

[0051]

[0052] According to Table 1, when the addition amount of disodium ethylenediaminetetraacetate is 50 mg, the charge density of the prepared flocculant is the largest and the performance is the best.

[0053] Table 2 Turbidity, UV 254 , Tetracycline removal rate (%)

[0054]

[0055] Application Example 2

[0056] Taking pH as a variable, the pH of the supernatant of Example 1 was changed to 7, 8, and 9, respectively, to obtain different flocculants a2, b2, and c2, respectively. The charge density of a2, b2, and c2 was tested, and the results are shown in Table 3. A2, b2, and c2 were used to treat simulated surface water containing tetracycline at different dosages, and the treatment results are shown in Table 4.

[0057] Table 3 Charge density (ueq / L)

[0058]

[0059]

[0060] It can be seen from Table 3 that when the pH of the supernatant is 8, the prepared flocculant has the largest charge density and the best performance.

[0061] Table 4 Turbidity, UV 254 , Tetracycline removal rate (%)

[0062]

[0063] Application Example 3

[0064] Taking methacryloyloxyethyl trimethyl ammonium chloride solution, vinyl acetate solution and potassium persulfate as variables, the addition amounts of methacryloyloxyethyl trimethyl ammonium chloride solution, vinyl acetate solution and potassium persulfate in Example 1 were changed, the addition amounts of methacryloyloxyethyl trimethyl ammonium chloride solution were 2.5 mL, 5 mL and 10 mL, the addition amounts of vinyl acetate solution were 1 mL, 2 mL and 4 mL, and the addition amounts of potassium persulfate were 25 mg, 50 mg and 100 mg, respectively (at this time, the mass ratio of potassium persulfate added for the first time and potassium persulfate added for the second time in Example 1 was changed according to a distribution ratio of 3:2), and different flocculants A, B, C, D, E, F, G, H and I were obtained respectively. The charge density of A, B, C, D, E, F, G, H and I was tested, and the results are shown in Table 5. A, B, C, D, E, F, G, H and I were used to treat simulated surface water containing tetracycline at different addition amounts, and the treatment results are shown in Tables 6, 7 and 8.

[0065] Table 5 Charge density

[0066]

[0067]

[0068] It can be seen from Table 5 that when 5 mL of methacryloyloxyethyltrimethylammonium chloride solution, 1 mL of vinyl acetate solution and 50 mg of potassium persulfate are added, the prepared flocculant I has the largest charge density and the best performance.

[0069] Table 6 Turbidity removal rate (%)

[0070] Dosage(mg / L) A B C D E F G H I 5 88.85 87.99 87.06 91.50 90.41 88.09 87.21 67.56 81.42 7.5 87.94 90.59 90.77 91.48 92.17 89.93 91.99 72.81 88.55 10 86.04 90.69 85.72 86.42 88.39 88.25 91.37 82.44 87.97 12.5 74.14 88.41 75.18 78.29 85.63 77.08 92.67 90.40 84.04 15 62.07 86.36 71.78 76.68 77.11 66.23 93.02 91.13 77.02

[0071] Table 7UV 254 Removal rate (%)

[0072] Dosage(mg / L) A B C D E F G H I 5 74.91 73.90 72.73 74.03 68.60 66.53 74.78 70.63 74.85 7.5 78.65 76.49 73.90 78.29 71.49 70.45 77.13 72.56 77.93 10 80.71 77.49 76.71 80.81 73.35 73.76 79.46 74.42 81.38 12.5 82.58 79.68 78.31 83.14 75.62 75.06 78.68 76.16 84.01 15 82.11 80.88 79.27 82.11 76.66 75.61 78.49 77.91 83.77

[0073] Table 8 Tetracycline removal rate (%)

[0074]

[0075]

[0076] From Table 6-8, we can see that flocculant I has a significant effect on UV 254 The removal rates of chloramphenicol and tetracycline are high, and the removal of turbidity is also at a high level.

[0077] Comparative Example 1

[0078] Preparation of flocculant:

[0079] (1) Weigh 2 g of papermaking pulp residue and add it to 200 mL of deionized water, add 1 g of sodium hydroxide, boil it in an oil bath at 130° C. for 1 h, centrifuge and take the supernatant, and adjust the pH to 8 with a 0.1 mol / L HCl solution;

[0080] (2) Place the reactor in a 70°C water bath, continue to introduce nitrogen and keep stirring for 15 minutes to remove air from the supernatant; keep introducing nitrogen, add 30 mg of potassium persulfate to the system and stir for 5 minutes, then add 50 mg of disodium ethylenediaminetetraacetate and stir for 10 minutes, add 5 mL of 75% methacryloyloxyethyltrimethylammonium chloride solution dropwise to the system, then add 20 mg of potassium persulfate and stir for 4 hours;

[0081] (3) After the reaction is completed, the mixture is cooled to room temperature, 300 mL of acetone is added to precipitate the product, and the residue is filtered and washed with pure water and then freeze-dried in vacuum to obtain the product.

[0082] Application Example 4

[0083] The flocculant prepared in Comparative Example 1 was used to treat simulated surface water containing tetracycline, and the treatment effects are listed in Table 9.

[0084] Table 9 Treatment effect of comparative flocculants

[0085] Flocculant dosage (mg / L) 7.5 10 12.5 15 Turbidity removal rate (%) 74.63 77.45 79.87 78.22 <![CDATA[UV 254 Removal rate (%)]]> 32.68 36.22 40.16 45.28 Tetracycline removal rate (%) 33.80 34.18 24.09 41.14

[0086] By comparing the coagulants prepared in the examples and comparative examples, it can be seen that the flocculant prepared in Example 1 of the present invention has an effect on UV 254 The removal rate and tetracycline removal rate are both increased, and the removal rate at the same dosage is increased by up to 40%. The flocculant in the present invention interacts more strongly with the antibiotics, and the coagulation effect is more obvious.

[0087] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing an amphiphilic papermaking pulp residue-based organic polymer flocculant, characterized in that: The following steps are involved: Add papermaking pulp residue into deionized water, then add sodium hydroxide, boil in oil bath, centrifuge to obtain supernatant, and adjust pH to 7-9; The pH-adjusted supernatant was heated and stirred under a nitrogen atmosphere, potassium persulfate was added to the system and stirred for reaction, then disodium ethylenediaminetetraacetate was added and stirred for reaction, and finally vinyl acetate solution, methacryloyloxyethyltrimethylammonium chloride solution and potassium persulfate were added and stirred for reaction; After the reaction is completed, the mixture is cooled to room temperature, and the reaction product is precipitated with acetone and dichloromethane. The reaction product is filtered, and the filter residue is washed with pure water and then vacuum-freeze-dried to obtain an amphiphilic papermaking pulp residue-based organic polymer flocculant.

2. The method for preparing the amphiphilic papermaking pulp residue-based organic polymer flocculant according to claim 1, characterized in that: The ratio of the papermaking pulp residue to the deionized water is 1 g: 100 mL; The mass ratio of the papermaking pulp residue to the sodium hydroxide is 2:(0.5-2); The mass ratio of the papermaking pulp residue to the total mass of potassium persulfate is 2:(0.025-0.1); The mass ratio of the papermaking pulp residue to disodium ethylenediaminetetraacetate is 2:(0-0.1); The dosage ratio of the papermaking pulp residue, the vinyl acetate solution and the methacryloyloxyethyltrimethylammonium chloride solution is 2g: (1-4) mL: (2.5-10) mL.

3. The method for preparing the amphiphilic papermaking pulp residue-based organic polymer flocculant according to claim 2, characterized in that: The pH of the papermaking pulp residue is 7.82, the ash content is 25wt%, the organic matter content is 70wt%, the lignin content is 20.5wt%, the cellulose content is 33.5wt%, and the residue rate is 78wt%.

4. An amphiphilic papermaking pulp residue-based organic polymer flocculant prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The flocculant has a charge density of 1440-1460ueq / L and a weight average molecular weight of 120kDa.

5. Use of the amphiphilic papermaking pulp residue-based organic polymer flocculant as claimed in claim 4 for simultaneously removing turbidity and organic matter from wastewater.

6. The use according to claim 5, characterized in that: The organic matter is humic acid and tetracycline.

7. The use according to claim 5, characterized in that: In the wastewater, the dosage of the amphiphilic papermaking pulp residue-based organic polymer flocculant is 7.5-12.5 mg / L.

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