Paper-making pulp residue-based star-shaped hydrophilic organic polymeric flocculant and preparation method thereof

Abstract

The invention discloses a papermaking pulp residue-based star-like hydrophilic organic polymeric flocculant and a preparation method thereof, and belongs to the technical field of solid waste resource utilization and water treatment agents. The preparation method of the papermaking pulp residue-based organic polymeric flocculant comprises the following steps: soaking papermaking pulp residues in an alkaline environment, and separating to obtain supernate; soaking the supernate in an acid environment, and separating to obtain a precipitate, namely a lignin extract; mixing and reacting the lignin extract, an acid-binding agent and an initiator in an organic solvent, and then pouring a reaction system into water to obtain a precipitate, namely a macromolecular initiator; and mixing the macroinitiator, a catalyst, a reducing agent, a reaction ligand and a reaction monomer in water, and carrying out a polymerization reaction to obtain the papermaking pulp residue-based organic polymeric flocculant. The prepared flocculant has a star-shaped structure, is good in hydrophilicity and can effectively control the molecular weight of a side chain.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste resource utilization and water treatment agents, and in particular to a papermaking pulp residue-based star-shaped hydrophilic organic polymer flocculant and a preparation method thereof. Background Art

[0002] At present, emerging organic pollution is one of the main sources of water pollution, among which the treatment of antibiotic pollutants is a research hotspot and difficulty. Among the commonly used water treatment technologies, coagulation has been widely used due to its simple operation and good effect. However, in the research process of coagulation treatment of antibiotics, it was found that traditional flocculants have limited effect on the treatment of antibiotics. For this reason, it is necessary to design flocculants with specific structures according to the characteristic structure of pollutants.

[0003] Among the many types of flocculants, natural organic polymer flocculants have unique advantages in the application of wastewater treatment and chemical industry due to the advantages of wide raw material sources, easy biodegradation and low toxicity. Papermaking pulp residue is the waste residue produced by paper mills in the pulping process, which contains rich biomass materials such as lignin, hemicellulose and cellulose. The papermaking industry produces a large amount of papermaking pulp residue every year, but only about 2% is separated and recycled as biomass raw materials, and most of the rest is burned as low-value fuel, resulting in a waste of resources. How to effectively utilize the biomass resources in papermaking pulp residue and apply it to the field of wastewater treatment to achieve waste treatment has important theoretical and practical significance.

[0004] At present, although there are reports on the use of biomass to prepare flocculants to treat antibiotic wastewater, most of them have to use finished products such as lignin or chitosan as raw materials, the structure of the resulting products is uncontrollable, most of them are linear or comb-like structures, it is difficult to form a strong interaction with antibiotic molecules, and the product has poor water solubility, which cannot meet the treatment requirements. Therefore, it is of great significance to develop organic polymer flocculants based on papermaking pulp residue with controllable structure, strong reaction activity and excellent water solubility. Summary of the invention

[0005] The purpose of the present invention is to provide a paper pulp residue-based star-shaped hydrophilic organic polymer flocculant and a preparation method to solve the above-mentioned problems in the background technology. The present invention provides a preparation method of a paper pulp residue-based organic polymer flocculant, which has mild reaction conditions, high product purity, good hydrophilicity, controllable structure of the synthesized flocculant, environmental friendliness, and good application value.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing a papermaking pulp residue-based organic polymer flocculant, comprising the following steps:

[0008] (1) soaking papermaking pulp residue in an alkaline environment to separate and obtain a supernatant; then soaking the supernatant in an acidic environment to separate and obtain a precipitate, which is a lignin extract;

[0009] (2) mixing the lignin extract, the acid-binding agent and the initiator in an organic solvent, reacting them, and then pouring the reaction system into water to obtain a precipitate, which is the macromolecular initiator;

[0010] (3) The macromolecular initiator, catalyst, reducing agent, reaction ligand and reaction monomer are mixed in water to undergo polymerization reaction to obtain a papermaking pulp residue-based organic polymer flocculant.

[0011] Preferably, in step (1), the pH value of the immersion in the alkaline environment is 10-13, the temperature is 80-130°C, and the time is 2 hours; the pH value of the immersion in the acidic environment is 1-3, the temperature is 20-80°C, and the time is 1-3 hours.

[0012] Preferably, in step (2): the acid binding agent is 4-dimethylaminopyridine, triethylamine or pyridine; the initiator is 2-bromoisobutyryl bromide; and the organic solvent is dimethylformamide or tetrahydrofuran.

[0013] Preferably, in step (2): the mass ratio of the lignin extract, the acid binding agent and the initiator is 1:0.5-2:0.5-2; the reaction temperature is 23-27°C and the reaction time is 12-24h.

[0014] Preferably, in step (3): the catalyst is copper bromide; the reducing agent is ascorbic acid; the reaction ligand is pentamethyldiethylenetriamine, 2,2′-bipyridine or tris[2-(dimethylamino)ethyl]amine; and the reaction monomer is methacryloyloxyethyltrimethylammonium chloride.

[0015] Preferably, in step (3): the mass ratio of the macromolecular initiator, the catalyst and the reaction monomer is 100:5-20:1000-8000, and the mass ratio of the catalyst to the reaction ligand and the reducing agent is 1:1-5:5-10.

[0016] Preferably, in step (3), the polymerization reaction is carried out at a temperature of 50-80° C., for a time of 2-24 hours, and in a protective atmosphere.

[0017] The second technical solution of the present invention is to provide a papermaking pulp residue-based organic polymer flocculant obtained according to the above preparation method.

[0018] The third technical solution of the present invention is to provide an application of the above-mentioned papermaking pulp residue-based organic polymer flocculant in removing antibiotics from wastewater.

[0019] Preferably, the type of the antibiotic is tetracycline, levofloxacin or norfloxacin; and the dosage of the papermaking pulp residue-based organic polymer flocculant in the wastewater is 5-20 mg / L.

[0020] The technical principles of the present invention are as follows:

[0021] The present invention uses papermaking pulp residue as a raw material, extracts lignin therein for subsequent preparation. Lignin first undergoes an esterification reaction with 2-bromoisobutyryl bromide to generate a lignin macromolecular initiator with an active site at the end, and then generates a hydrophilic organic polymer flocculant with a star structure by reacting with a reaction monomer under the action of a catalyst, a reaction ligand and a reducing agent through atom transfer free radical polymerization technology. The obtained flocculant has a certain interaction with antibiotics, and its treatment capacity for antibiotic-containing wastewater is higher than that of a flocculant prepared by a traditional free radical polymerization method.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The invention utilizes alkali lignin in papermaking pulp residue and grafts cationic monomers into the lignin main body through atom transfer radical polymerization technology. The obtained papermaking pulp residue-based organic polymer flocculant has a star-shaped structure, good hydrophilicity, and can effectively control the side chain molecular weight.

[0024] The flocculant prepared by the present invention has better treatment capacity for antibiotic-containing wastewater than existing lignin-based flocculant products, and a dosage of about 10 mg / L can achieve an antibiotic removal rate of 70%.

[0025] The invention provides a method for preparing a papermaking pulp residue-based organic polymer flocculant. The method has mild reaction conditions, high product purity, good hydrophilicity, controllable structure of the synthesized flocculant, is environmentally friendly, and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is the infrared spectrum of the lignin extract in Example 1.

[0028] Figure 2 This is the infrared spectrum of the macromolecular initiator in Example 1.

[0029] Figure 3This is the infrared spectrum of the papermaking pulp residue-based organic polymer flocculant in Example 1.

[0030] Figure 4 This is a transmission electron micrograph of the papermaking pulp residue-based organic polymer flocculant in Example 1.

[0031] Figure 5 This is the reaction kinetics diagram of a1.

[0032] Figure 6 This is the reaction kinetics diagram of b1.

[0033] Figure 7 This is the reaction kinetics diagram of c1.

[0034] Figure 8 This is the water contact angle diagram of a1.

[0035] Fig. 9 This is the water contact angle diagram of b1.

[0036] Fig.10 This is the water contact angle diagram of c1. DETAILED DESCRIPTION

[0037] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0038] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the 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.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0040] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.

[0041] The present invention provides a method for preparing a papermaking pulp residue-based organic polymer flocculant, comprising the following steps:

[0042] (1) soaking papermaking pulp residue in an alkaline environment to separate and obtain a supernatant; then soaking the supernatant in an acidic environment to separate and obtain a precipitate, which is a lignin extract;

[0043] (2) mixing the lignin extract, the acid-binding agent and the initiator in an organic solvent, reacting them, and then pouring the reaction system into water to obtain a precipitate, which is the macromolecular initiator;

[0044] (3) The macromolecular initiator, catalyst, reducing agent, reaction ligand and reaction monomer are mixed in water to undergo polymerization reaction to obtain a papermaking pulp residue-based organic polymer flocculant.

[0045] Preferably, in step (1), the pH value of the immersion in the alkaline environment is 10-13, the temperature is 80-130°C, and the time is 2 hours; the pH value of the immersion in the acidic environment is 1-3, the temperature is 20-80°C, and the time is 1-3 hours. More preferably, the pH value of the immersion in the alkaline environment is 12, the temperature is 120°C, and the pH value of the immersion in the acidic environment is 2, the temperature is 20°C, and the time is 2 hours.

[0046] Preferably, in step (1), the pH value is adjusted by sodium hydroxide or 1 mol / L hydrochloric acid solution; the separation method is centrifugation or vacuum filtration. More preferably, the separation method for obtaining the supernatant is vacuum filtration; the separation method for obtaining the precipitate is centrifugation.

[0047] Preferably, the acid binding agent is 4-dimethylaminopyridine, triethylamine or pyridine; the initiator is 2-bromoisobutyryl bromide, more preferably 4-dimethylaminopyridine; the organic solvent is dimethylformamide or tetrahydrofuran, more preferably dimethylformamide.

[0048] Preferably, the mass ratio of the lignin extract, the acid-binding agent and the initiator is 1:0.5-2:0.5-2, more preferably 1:0.5:1; the reaction temperature is 23-27°C, and the reaction time is 12-24h, more preferably 24h.

[0049] Preferably, the reaction ligand is pentamethyldiethylenetriamine, 2,2′-bipyridine or tris[2-(dimethylamino)ethyl]amine, more preferably pentamethyldiethylenetriamine.

[0050] Preferably, the mass ratio of the macromolecular initiator, the catalyst and the reaction monomer is 100:5-20:1000-8000, more preferably 100:10:2000; the mass ratio of the catalyst to the reaction ligand and the reducing agent is 1:1-5:5-10, more preferably 1:2:7.

[0051] Preferably, in step (3), the polymerization reaction temperature is 50-80°C, the time is 2-24 hours, and the atmosphere is a protective atmosphere. More preferably, the polymerization reaction temperature is 70°C, and the time is 3 hours.

[0052] The present invention also provides a use of the above-mentioned papermaking pulp residue-based organic polymer flocculant in removing antibiotics from wastewater.

[0053] Preferably, the dosage of the papermaking pulp residue-based organic polymer flocculant in the wastewater is 5-20 mg / L, more preferably 10 mg / L.

[0054] Unless otherwise specified, the "room temperature" in the present invention is 25±2°C.

[0055] The preparation method of the simulated antibiotic wastewater used in the present invention is:

[0056] (1) Weigh 1 g of humic acid and 0.4 g of sodium hydroxide and dissolve them in deionized water to make the volume 1 L to obtain a humic acid reserve solution;

[0057] (2) Weigh 5 g of kaolin and place it in 1 L of deionized water, take the supernatant to obtain a kaolin reserve solution;

[0058] (3) Weigh 1 g of tetracycline, levofloxacin or norfloxacin and dissolve them in 1 L of tap water to obtain different types of antibiotic stock solutions;

[0059] (4) Take 10 mL of the above-mentioned humic acid reserve solution, 10 mL of kaolin reserve solution, and 10 mL of antibiotic reserve solution and dissolve them in 1 L of tap water to obtain simulated antibiotic wastewater.

[0060] The lignin content of the papermaking pulp residue used in the following examples and comparative examples of the present invention is 58.9 wt %, the hemicellulose content is 6.3 wt %, and the cellulose content is 7.1 wt %.

[0061] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

[0062] Example 1

[0063] A method for preparing a papermaking pulp residue-based organic polymer flocculant, comprising the following steps:

[0064] (1) 5.0 g of papermaking pulp residue was added to 200 mL of deionized water, 2.0 g of sodium hydroxide was added to adjust the pH to 12, the mixture was placed in an oil bath at 120° C. for 2 h, and vacuum filtered to obtain a supernatant; 1 mol / L hydrochloric acid was used to adjust the pH of the supernatant to 2.0, the mixture was allowed to stand at 20° C. for 2 h, and centrifuged to obtain a precipitate, which was washed with pure water and then freeze-dried in a vacuum to obtain a lignin extract;

[0065] (2) 0.5 g of lignin extract and 0.25 g of 4-dimethylaminopyridine were dissolved in 20 mL of dimethylformamide, and 0.5 g of 2-bromoisobutyryl bromide was added dropwise in an ice-water bath at 4°C, and then reacted at room temperature for 24 h. The reaction system was then poured into 300 mL of distilled water to obtain a precipitate, which was centrifuged and vacuum-freezed to obtain a macromolecular initiator;

[0066] (3) 200 mg of the macromolecular initiator was dissolved in 10 mL of deionized water. Under nitrogen protection, 20 mg of copper bromide, 40 mg of pentamethyldiethylenetriamine and 140 mg of ascorbic acid were added to the system. Then 4.0 g of methacryloyloxyethyltrimethylammonium chloride was added to the reaction system. The polymerization reaction was carried out under heating in an oil bath at 70° C. for 3 h. After the reaction was completed, the reaction was cooled to room temperature, the reaction product was precipitated with acetone, and the reaction product was washed with anhydrous ethanol and deionized water, and vacuum freeze-dried to obtain a papermaking pulp residue-based organic polymer flocculant (denoted as c1).

[0067] The materials in Example 1 were tested by infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The test results are as follows: Figure 1-4 shown.

[0068] Figure 1 This is the infrared spectrum of the lignin extract in Example 1.

[0069] Figure 2 This is the infrared spectrum of the macromolecular initiator in Example 1.

[0070] Figure 3 This is the infrared spectrum of the papermaking pulp residue-based organic polymer flocculant in Example 1.

[0071] Figure 4 This is a transmission electron micrograph of the papermaking pulp residue-based organic polymer flocculant in Example 1.

[0072] Depend on Figure 1 It can be seen that the lignin extract extracted in step (1) contains hydroxyl structures.

[0073] Depend on Figure 2 It can be seen that the hydroxyl group in the macromolecular initiator in step (2) and 2-bromoisobutyryl bromide undergo an esterification reaction, so the 1740 cm -1 There are strong absorption peaks on the left and right, which are attributed to the stretching vibration peak of the C=O functional group.

[0074] Depend on Figure 3 It can be seen that the macromolecular initiator and the reaction monomer successfully undergo free radical polymerization, so in the infrared spectrum at 1720, 1470, and 1230 cm -1Characteristic peaks appeared nearby, representing C=0, -CH3 and quaternary ammonium groups in the monomer methacryloyloxyethyltrimethylammonium chloride.

[0075] Depend on Figure 4 It can be seen that the papermaking pulp residue-based organic polymer flocculant obtained in step (3) has a star-shaped structure.

[0076] Comparative Example 1 (Traditional Free Radical Polymerization Method)

[0077] A method for preparing a papermaking pulp residue-based flocculant, comprising the following steps:

[0078] (1) 5.0 g of papermaking pulp residue was added to 200 mL of deionized water, 2.0 g of sodium hydroxide was added to adjust the pH to 12, the mixture was placed in an oil bath at 120° C. for 2 h, and vacuum filtered to obtain a supernatant; 1 mol / L hydrochloric acid was used to adjust the pH of the supernatant to 2.0, the mixture was allowed to stand at 20° C. for 2 h, and centrifuged to obtain a precipitate, which was washed with pure water and then freeze-dried in a vacuum to obtain a lignin extract;

[0079] (2) 0.5 g of lignin extract was dissolved in 100 mL of water, the pH was adjusted to 9.0, and the mixture was poured into a three-necked flask, which was then placed in a 70°C water bath, and nitrogen was continuously introduced and stirred for 15 min. Then, 50 mg of potassium persulfate was added to the system and stirred for 5 min. Then, 50 mg of disodium ethylenediaminetetraacetate was added and stirred for 10 min. Finally, 10 mL of methacryloyloxyethyltrimethylammonium chloride was added dropwise to the system and stirred for 4 h. After the reaction was completed, the mixture was cooled to room temperature, the reaction product was precipitated with acetone, and the reaction product was washed with anhydrous ethanol and deionized water, and vacuum freeze-dried to obtain a papermaking pulp residue-based flocculant.

[0080] Comparative Example 2

[0081] The only difference from Example 1 is that the polymerization reaction time is changed from 3 h to 24 h, and deionized water is replaced by an equal volume of dimethylformamide or tetrahydrofuran to obtain a papermaking pulp residue-based organic polymer flocculant (the product in the case of dimethylformamide is denoted as a1, and the product in the case of tetrahydrofuran is denoted as b1).

[0082] Comparative Example 3

[0083] The only difference from Example 1 is that the pH of the supernatant pH adjustment step with hydrochloric acid in step (1) is modified to 1.0 and 3.0 to obtain a papermaking pulp residue-based organic polymer flocculant (the product at pH 1.0 is denoted as a2, and the product at pH 3.0 is denoted as b2).

[0084] Comparative Example 4

[0085] The only difference from Example 1 is that the amount of 4-dimethylaminopyridine added is changed to 1 g, and the amount of 2-bromoisobutyryl bromide added is changed to 1 g. The obtained product is recorded as a3;

[0086] The added amounts of 4-dimethylaminopyridine and 2-bromoisobutyryl bromide were changed to 0.5 g and 0.25 g, respectively, and the obtained product was recorded as b3.

[0087] Comparative Example 5

[0088] The only difference from Example 1 is that the amount of copper bromide added is changed to 10 mg, and the amount of methacryloyloxyethyltrimethylammonium chloride added is changed to 16.0 g. The obtained product is recorded as a4;

[0089] The added amounts of copper bromide and methacryloyloxyethyltrimethylammonium chloride were changed to 40 mg and 2.0 g, respectively, and the obtained product was designated as b4.

[0090] Application Example 1

[0091] The polymerization reaction process in step (3) of a1, b1 and c1 was studied for reaction kinetics. During the reaction, samples were taken at the same time intervals and the monomer conversion rate was tested by nuclear magnetic resonance hydrogen spectrum. The test results are shown in Figure 5-7 The water contact angles of a1, b1, and c1 were tested respectively. The results are shown in Figure 8-10 .

[0092] Figure 5 This is the reaction kinetics diagram of a1.

[0093] Figure 6 This is the reaction kinetics diagram of b1.

[0094] Figure 7 This is the reaction kinetics diagram of c1.

[0095] Figure 8 This is the water contact angle diagram of a1.

[0096] Fig. 9 This is the water contact angle diagram of b1.

[0097] Fig.10 This is the water contact angle diagram of c1.

[0098] Depend on Figure 5-7 It can be seen that the monomer conversion rates of a1, b1, and c1 increase linearly with the increase of reaction time, indicating that the flocculant is controllable. When the reaction solvent is different, the monomer conversion rate varies greatly; among them, when the solvent is deionized water (c1), the monomer conversion rate reaches 60% after 3 hours of reaction, while when the solvent is dimethylformamide or tetrahydrofuran (a1, b1), the monomer conversion rate after 24 hours of reaction is only about 58%.

[0099] Figure 8-10 The results show that the solvent has a great influence on the water solubility of the synthesized flocculant. When the solvent is deionized water, the resulting flocculant has better hydrophilicity; while when the solvent is dimethylformamide or tetrahydrofuran, the resulting flocculant has poor hydrophilicity.

[0100] A1, b1, and c1 were used to treat simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin at different dosages (treatment time 60 min) to statistically analyze the antibiotic removal rate. The results are shown in Table 1.

[0101] The calculation formula of antibiotic removal rate is: Antibiotic removal rate (%) = (original antibiotic concentration - antibiotic concentration after treatment) / original antibiotic concentration

[0102] Table 1 Removal rates of tetracycline, levofloxacin and norfloxacin (%)

[0103]

[0104] As can be seen from Table 1, when the solvent is deionized water, the prepared flocculant (c1) has the best removal effect on tetracycline, levofloxacin or norfloxacin. This is because the synthesized product has better water solubility when the solvent is deionized water, which is conducive to its expansion in water and exerting electrical neutralization and adsorption bridging effects. It can also be seen from Table 1 that when the dosage exceeds 10 mg / L, the efficiency of c1 in removing antibiotics decreases. This is because the flocculant relies on electrical neutralization to remove antibiotics. When the optimal dosage is reached, increasing the amount of flocculant will cause the system to have opposite charges, resulting in back mixing and reducing the removal effect.

[0105] Application Example 2

[0106] A2, b2, and c1 were used to treat simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin at different dosages (treatment time 60 min) to statistically analyze the antibiotic removal rate. The results are shown in Table 2.

[0107] Table 2 Removal rate of tetracycline, levofloxacin and norfloxacin (%)

[0108]

[0109] It can be seen from Table 2 that when the pH is 2.0, the prepared flocculant has the best effect on removing tetracycline, levofloxacin or norfloxacin.

[0110] Application Example 3

[0111] A3, b3, and c1 were used to treat simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin at different dosages (treatment time 60 min) to statistically analyze the antibiotic removal rate. The results are shown in Table 3.

[0112] Table 3 Removal rates of tetracycline, levofloxacin and norfloxacin (%)

[0113]

[0114] It can be seen from Table 3 that when the mass ratio of lignin, acid-binding agent and 2-bromoisobutyryl bromide is 1:0.5:1 (c1), the prepared flocculant has the best effect on removing tetracycline, levofloxacin or norfloxacin.

[0115] Application Example 4

[0116] A4, b4, and c1 were used to treat simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin at different dosages (treatment time 60 min) to statistically analyze the antibiotic removal rate. The results are shown in Table 4.

[0117] Table 4 Removal rates of tetracycline, levofloxacin and norfloxacin (%)

[0118]

[0119] It can be seen from Table 4 that when the mass ratio of macromolecular initiator, catalyst and monomer is 100:10:2000 (c1), the prepared flocculant has the best effect on removing tetracycline, levofloxacin or norfloxacin.

[0120] Application Example 5

[0121] The product of Comparative Example 1 was used to treat simulated antibiotic wastewater containing tetracycline, levofloxacin or norfloxacin at different dosages (treatment time 60 min) to statistically analyze the antibiotic removal rate. The results are shown in Table 5.

[0122] Table 5 Removal rate of tetracycline, levofloxacin and norfloxacin (%)

[0123]

[0124] By comparing the flocculants prepared in Example 1 and Comparative Example 1, it can be seen that the flocculants prepared in Example 1 of the present invention have increased removal rates of tetracycline, levofloxacin and norfloxacin, and the removal rate at the same dosage is increased by up to 30%. This is mainly because the flocculants in the present invention have stronger interaction with antibiotics and more obvious flocculation effect.

[0125] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a papermaking pulp residue-based organic polymer flocculant, characterized in that: The following steps are involved: (1) soaking paper pulp residue in an alkaline environment to separate and obtain a supernatant; then soaking the supernatant in an acidic environment to separate and obtain a precipitate, which is a lignin extract; (2) mixing the lignin extract, the acid-binding agent and the initiator in an organic solvent, reacting them, and then pouring the reaction system into water to obtain a precipitate, which is the macromolecular initiator; (3) The macromolecular initiator, catalyst, reducing agent, reaction ligand and reaction monomer are mixed in water to undergo polymerization reaction to obtain a papermaking pulp residue-based organic polymer flocculant.

2. The preparation method according to claim 1, characterized in that: In step (1), the pH value of the immersion in the alkaline environment is 10-13, the temperature is 80-130° C., and the time is 2 hours; the pH value of the immersion in the acidic environment is 1-3, the temperature is 20-80° C., and the time is 1-3 hours.

3. The preparation method according to claim 1, characterized in that: In step (2), the acid binding agent is 4-dimethylaminopyridine, triethylamine or pyridine; the initiator is 2-bromoisobutyryl bromide; and the organic solvent is dimethylformamide or tetrahydrofuran.

4. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the lignin extract, the acid-binding agent and the initiator is 1:0.5-2:0.5-2; the reaction temperature is 23-27° C. and the reaction time is 12-24 hours.

5. The preparation method according to claim 1, characterized in that: In step (3), the catalyst is copper bromide; the reducing agent is ascorbic acid; the reaction ligand is pentamethyldiethylenetriamine, 2,2′-bipyridine or tris[2-(dimethylamino)ethyl]amine; and the reaction monomer is methacryloyloxyethyltrimethylammonium chloride.

6. The preparation method according to claim 1, characterized in that: In step (3): the mass ratio of the macromolecular initiator, the catalyst and the reaction monomer is 100:5-20:1000-8000, and the mass ratio of the catalyst to the reaction ligand and the reducing agent is 1:1-5:5-10.

7. The preparation method according to claim 1, characterized in that: In step (3): the polymerization reaction temperature is 50-80°C, the time is 2-24h, and the atmosphere is a protective atmosphere.

8. A papermaking pulp residue-based organic polymer flocculant obtained according to the preparation method according to any one of claims 1 to 7.

9. Use of the papermaking pulp residue-based organic polymer flocculant according to claim 8 in removing antibiotics from wastewater.

10. The use according to claim 9, characterized in that: The type of the antibiotic is tetracycline, levofloxacin or norfloxacin; the dosage of the papermaking pulp residue-based organic polymer flocculant in the wastewater is 5-20 mg / L.

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