A star-shaped hydrophilic organic polymeric flocculant based on paper pulp residue and its preparation method

Abstract

This invention discloses a star-shaped hydrophilic organic polymeric flocculant based on papermaking pulp residue and its preparation method, belonging 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 of this invention includes the following steps: soaking papermaking pulp residue in an alkaline environment and separating to obtain a supernatant; then soaking the supernatant in an acidic environment and separating to obtain a precipitate, which is a lignin extract; mixing the lignin extract, an acid-binding agent, and an initiator in an organic solvent and reacting; then pouring the reaction system into water to obtain a precipitate, which is a macromolecular initiator; mixing the macromolecular initiator, a catalyst, a reducing agent, a reaction ligand, and a reaction monomer in water and polymerizing to obtain the papermaking pulp residue-based organic polymeric flocculant. The flocculant obtained by this invention has a star-shaped structure, good hydrophilicity, and can effectively control the molecular weight of the side chains.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and water treatment agents, and in particular to a paper pulp residue-based star-shaped hydrophilic organic polymer flocculant and its preparation method. Background Technology

[0002] Currently, emerging organic pollutants are one of the main sources of water pollution, with antibiotic pollution being a research hotspot and challenge. Among commonly used water treatment technologies, coagulation is widely used due to its simplicity and effectiveness. However, research on coagulation for antibiotic treatment has revealed limited effectiveness of traditional flocculants. Therefore, it is necessary to design flocculants with specific structures based on the characteristic structure of the pollutants.

[0003] Among the many types of flocculants, natural organic polymeric flocculants have unique advantages in wastewater treatment and chemical applications due to their wide availability of raw materials, easy biodegradability, and low toxicity. Paper pulp residue is a waste product generated during the pulping process in paper mills, containing abundant lignin, hemicellulose, and cellulose, among other biomass materials. The paper industry generates a large amount of pulp residue annually, but only about 2% is separated and recycled as biomass raw materials; the majority is burned as low-value fuel, resulting in resource waste. How to effectively utilize the biomass resources in paper pulp residue and apply them to wastewater treatment to achieve waste-to-waste treatment has significant theoretical and practical implications.

[0004] Currently, while there are reports of using biomass to prepare flocculants for treating antibiotic wastewater, most of these technologies suffer from drawbacks, including the requirement to use finished products such as lignin or chitosan as raw materials, uncontrollable product structure (often linear or comb-like), difficulty in forming strong interactions with antibiotic molecules, and poor water solubility. These limitations fail to meet treatment requirements. Therefore, developing paper pulp residue-based organic polymeric flocculants with controllable structure, high reactivity, and excellent water solubility is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a star-shaped hydrophilic organic polymeric flocculant based on papermaking pulp residue and its preparation method, thereby solving the aforementioned problems in the background art. This invention provides a method for preparing a papermaking pulp residue-based organic polymeric flocculant. This method features mild reaction conditions, high product purity, good hydrophilicity, controllable flocculant structure, and environmental friendliness, making it highly valuable for application.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

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

[0008] (1) The paper pulp residue is soaked in an alkaline environment and the supernatant is obtained by separation; then the supernatant is soaked in an acidic environment and the precipitate is obtained by separation, which is the lignin extract;

[0009] (2) The lignin extract, acid binder and initiator are mixed in an organic solvent and reacted. Then the reaction system is poured 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 and polymerized to obtain paper pulp residue-based organic polymer flocculant.

[0011] Preferably, in step (1): the pH value of the soaking in the alkaline environment is 10-13, the temperature is 80-130℃, and the time is 2h; the pH value of the soaking in the acidic environment is 1-3, the temperature is 20-80℃, and the time is 1-3h.

[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 binder and the initiator is 1:0.5-2:0.5-2; the reaction temperature is 23-27℃ and the 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, catalyst and reactant is 100:5-20:1000-8000, and the mass ratio of the catalyst to the reactant ligand and 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 2-24 hours, and the atmosphere is a protective atmosphere.

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

[0018] The third technical solution of the present invention provides an application of the above-mentioned paper pulp residue-based organic polymer flocculant in the removal of antibiotics from wastewater.

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

[0020] The technical principle of this invention is as follows:

[0021] This invention utilizes paper pulp residue as raw material to extract lignin for subsequent preparations. The lignin first undergoes an esterification reaction with 2-bromoisobutyryl bromide to generate a lignin macromolecular initiator with terminal active sites. Then, through atom transfer radical polymerization, it reacts with monomers under the action of a catalyst, reaction ligands, and a reducing agent to generate a star-shaped, hydrophilic organic polymeric flocculant. The resulting flocculant exhibits certain interactions with antibiotics and demonstrates a higher treatment capacity for antibiotic-containing wastewater than flocculants prepared by traditional free radical polymerization methods.

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

[0023] This invention utilizes alkali lignin in papermaking pulp residue and grafts cationic monomers onto the lignin matrix through atom transfer radical polymerization technology. The resulting papermaking pulp residue-based organic polymer flocculant has a star-shaped structure, good hydrophilicity, and can effectively control the molecular weight of the side chains.

[0024] The flocculant prepared by this invention has a better treatment capacity for antibiotic-containing wastewater than existing lignin-based flocculant products. With an addition of about 10 mg / L, an antibiotic removal rate of 70% can be achieved.

[0025] This invention provides a method for preparing a paper pulp residue-based organic polymer flocculant. The method has mild reaction conditions, high product purity, good hydrophilicity, controllable flocculant structure, and is environmentally friendly, with good application value. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the infrared spectrum of the lignin extract from Example 1.

[0028] Figure 2 The image shows the infrared spectrum of the macromolecular initiator in Example 1.

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

[0030] Figure 4 This is a transmission electron microscope (TEM) image of the paper pulp residue-based organic polymer flocculant in Example 1.

[0031] Figure 5 The reaction kinetics diagram for a1 is shown.

[0032] Figure 6 The reaction kinetics diagram is for b1.

[0033] Figure 7 The reaction kinetics diagram is for c1.

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

[0035] Figure 9 This is the water contact angle diagram for b1.

[0036] Figure 10 This is the water contact angle diagram for c1. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0038] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0040] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0041] This invention provides a method for preparing a paper pulp residue-based organic polymeric flocculant, comprising the following steps:

[0042] (1) The paper pulp residue is soaked in an alkaline environment and the supernatant is obtained by separation; then the supernatant is soaked in an acidic environment and the precipitate is obtained by separation, which is the lignin extract;

[0043] (2) The lignin extract, acid binder and initiator are mixed in an organic solvent and reacted. Then the reaction system is poured 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 and polymerized to obtain paper pulp residue-based organic polymer flocculant.

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

[0046] Preferably, in step (1), the pH value is adjusted by sodium hydroxide or a 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; and the organic solvent is dimethylformamide or tetrahydrofuran, more preferably dimethylformamide.

[0048] Preferably, the mass ratio of the lignin extract, acid binder and initiator is 1:0.5-2:0.5-2, more preferably 1:0.5:1; the reaction temperature is 23-27℃, 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, catalyst, and reactant monomer is 100:5-20:1000-8000, more preferably 100:10:2000; the mass ratio of the catalyst to the reactant ligand and reducing agent is 1:1-5:5-10, more preferably 1:2:7.

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

[0052] The present invention also provides an application of the above-mentioned paper pulp residue-based organic polymer flocculant in the removal of antibiotics from wastewater.

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

[0054] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0055] The method for preparing simulated antibiotic wastewater used in this invention is as follows:

[0056] (1) Weigh 1g of humic acid and 0.4g of sodium hydroxide and dissolve them in deionized water, then make up to 1L to obtain humic acid stock solution;

[0057] (2) Weigh 5g of kaolin and place it in 1L of deionized water. Take the supernatant to obtain the kaolin stock solution.

[0058] (3) Weigh 1g of tetracycline, levofloxacin or norfloxacin, dissolve them in 1L of tap water respectively, and obtain different kinds of antibiotic solutions.

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

[0060] In the following embodiments and comparative examples of the present invention, the lignin content in the pulp residue 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 embodiments and comparative examples of the present invention are commercially available products.

[0062] Example 1

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

[0064] (1) Add 5.0g of paper pulp residue to 200mL of deionized water, add 2.0g of sodium hydroxide to adjust the pH to 12, heat in an oil bath at 120℃ for 2h, and vacuum filter to obtain the supernatant; adjust the pH of the supernatant to 2.0 with 1mol / L hydrochloric acid, let stand at 20℃ for 2h, centrifuge to obtain the precipitate, wash the precipitate with pure water and freeze dry under vacuum to obtain lignin extract;

[0065] (2) Dissolve 0.5g of lignin extract and 0.25g of 4-dimethylaminopyridine in 20mL of dimethylformamide, add 0.5g of 2-bromoisobutyryl bromide dropwise under an ice-water bath at 4℃, and then react at room temperature for 24h. Then pour the reaction system into 300mL of distilled water to obtain a precipitate. After centrifuging the precipitate, freeze dry it under vacuum to obtain a macromolecular initiator.

[0066] (3) Dissolve 200 mg of macromolecular initiator in 10 mL of deionized water, add 20 mg of copper bromide, 40 mg of pentamethyldiethylenetriamine and 140 mg of ascorbic acid to the system under nitrogen protection, and then add 4.0 g of methacryloyloxyethyltrimethylammonium chloride to the above reaction system. The polymerization reaction is carried out at 70 °C in an oil bath for 3 h. After the reaction is completed, cool to room temperature, precipitate the reaction product with acetone, wash the reaction product with anhydrous ethanol and deionized water, and freeze dry under vacuum to obtain paper pulp residue-based organic polymer flocculant (denoted as c1).

[0067] The materials in Example 1 were subjected to Fourier Transmission Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM) tests, and the test results are as follows: Figure 1-4 As shown.

[0068] Figure 1 The image shows the infrared spectrum of the lignin extract from Example 1.

[0069] Figure 2 The image shows the infrared spectrum of the macromolecular initiator in Example 1.

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

[0071] Figure 4 This is a transmission electron microscope (TEM) image of the paper pulp residue-based organic polymer flocculant in Example 1.

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

[0073] Depend on Figure 2 It can be seen that the hydroxyl group in the macromolecular initiator in step (2) underwent an esterification reaction with 2-bromoisobutyryl bromide, so the result is visible at 1740 cm⁻¹ in the infrared spectrum. -1 Strong absorption peaks appeared on both sides, which are attributed to the stretching vibration peaks of the C=O functional group.

[0074] Depend on Figure 3 It can be seen that the macromolecular initiator and the reactant monomers successfully underwent a free radical polymerization reaction, hence the appearance of these reactions at 1720, 1470, and 1230 cm⁻¹ in the infrared spectrum. -1Characteristic peaks appeared nearby, representing the C=O, -CH3, and quaternary ammonium groups in the monomer methacryloyloxyethyltrimethylammonium chloride, respectively.

[0075] Depend on Figure 4 It can be seen that the paper 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 paper pulp residue-based flocculant, comprising the following steps:

[0078] (1) Add 5.0g of paper pulp residue to 200mL of deionized water, add 2.0g of sodium hydroxide to adjust the pH to 12, heat in an oil bath at 120℃ for 2h, and vacuum filter to obtain the supernatant; adjust the pH of the supernatant to 2.0 with 1mol / L hydrochloric acid, let stand at 20℃ for 2h, centrifuge to obtain the precipitate, wash the precipitate with pure water and freeze dry under vacuum to obtain lignin extract;

[0079] (2) Dissolve 0.5g of lignin extract in 100mL of water, adjust the pH to 9.0, pour into a three-necked flask, and then place it in a 70℃ water bath. Stir continuously with nitrogen gas for 15min, then add 50mg of potassium persulfate to the system and stir for 5min. Then add 50mg of disodium ethylenediaminetetraacetate and stir for 10min. Finally, add 10mL of methacryloyloxyethyltrimethylammonium chloride dropwise to the system and stir for 4h. After the reaction is completed, cool to room temperature, precipitate the reaction product with acetone, wash the reaction product with anhydrous ethanol and deionized water, and freeze dry under vacuum to obtain the paper pulp residue-based flocculant.

[0080] Comparative Example 2

[0081] The only difference from Example 1 is that the polymerization reaction time was changed from 3h to 24h, and the deionized water was replaced with an equal volume of dimethylformamide or tetrahydrofuran to obtain a paper pulp residue-based organic polymer flocculant (the product with dimethylformamide is denoted as a1, and the product with 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 in step (1) is modified to 1.0 and 3.0 to obtain paper 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 was changed to 1g and the amount of 2-bromoisobutyryl bromide added was changed to 1g, and the resulting product was denoted as a3;

[0086] The amount of 4-dimethylaminopyridine added was modified to 0.5 g, and the amount of 2-bromoisobutyryl bromide added was modified to 0.25 g. The resulting product was denoted as b3.

[0087] Comparative Example 5

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

[0089] The amount of copper bromide added was modified to 40 mg, and the amount of methacryloyloxyethyltrimethylammonium chloride added was modified to 2.0 g. The resulting product was denoted as b4.

[0090] Application Example 1

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

[0092] Figure 5 The reaction kinetics diagram for a1 is shown.

[0093] Figure 6 The reaction kinetics diagram is for b1.

[0094] Figure 7 The reaction kinetics diagram is for c1.

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

[0096] Figure 9 This is the water contact angle diagram for b1.

[0097] Figure 10 This is the water contact angle diagram for c1.

[0098] Depend on Figure 5-7 It can be seen that the monomer conversion rates of a1, b1, and c1 show a linear increasing trend with increasing reaction time, indicating that the flocculant is controllable. The monomer conversion rates vary significantly depending on the reaction solvent; for example, when the solvent is deionized water (c1), the monomer conversion rate reaches 60% after 3 hours of reaction, while when the solvents are dimethylformamide or tetrahydrofuran (a1, b1), the monomer conversion rate is only about 58% after 24 hours of reaction.

[0099] Figure 8-10 The results showed that the solvent has a significant impact 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 poorer hydrophilicity.

[0100] The simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin was treated with different dosages (treatment time 60 min) using the methods a1, b1, and c1 to calculate the antibiotic removal rate. The results are shown in Table 1.

[0101] The formula for calculating antibiotic removal rate is: Antibiotic removal rate (%) = (Original antibiotic concentration - Post-treatment antibiotic concentration) / Original antibiotic concentration

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

[0103]

[0104] As shown in Table 1, the flocculant (C1) prepared using deionized water as the solvent exhibits the best removal efficiency for tetracycline, levofloxacin, or norfloxacin. This is because the product synthesized using deionized water has better water solubility, which facilitates its expansion in water and allows it to perform charge neutralization and adsorption bridging functions. Table 1 also shows that when the dosage exceeds 10 mg / L, the antibiotic removal efficiency of C1 decreases. This is because the flocculant removes antibiotics through charge neutralization; after reaching the optimal dosage, further increases in the amount of flocculant will cause the system to acquire opposite charges, resulting in back-mixing and a decrease in removal efficiency.

[0105] Application Example 2

[0106] Simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin was treated with different dosages (treatment time 60 min) using a2, b2, and c1 methods to statistically analyze antibiotic removal rates. The results are shown in Table 2.

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

[0108]

[0109] As can be seen from Table 2, the flocculant prepared at pH 2.0 was most effective in removing tetracycline, levofloxacin, or norfloxacin.

[0110] Application Example 3

[0111] Simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin was treated with different dosages (treatment time 60 min) using a3, b3, and c1 samples to calculate the antibiotic removal rate. The results are shown in Table 3.

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

[0113]

[0114] As can be seen from Table 3, when the mass ratio of lignin, acid binder 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] Simulated antibiotic wastewater containing tetracycline, levofloxacin, or norfloxacin was treated with different dosages (treatment time 60 min) using a4, b4, and c1 samples to calculate the antibiotic removal rate. The results are shown in Table 4.

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

[0118]

[0119] As can be seen from Table 4, 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 calculate the antibiotic removal rate. The results are shown in Table 5.

[0122] Table 5 Removal rates (%) 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 flocculant prepared in Example 1 of this invention has increased the removal rates of tetracycline, levofloxacin, and norfloxacin, with the removal rate increasing by up to 30% at the same dosage. This is mainly because the flocculant in this invention has a stronger interaction with the antibiotics, resulting in a more significant flocculation effect.

[0125] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a paper pulp residue-based organic polymeric flocculant, characterized in that, The steps are as follows: (1) Add 5.0 g of paper pulp residue to 200 mL of deionized water, add 2.0 g of sodium hydroxide to adjust the pH to 12, heat in an oil bath at 120℃ for 2 h, and vacuum filter to obtain the supernatant; adjust the pH of the supernatant to 2.0 with 1 mol / L hydrochloric acid, let stand at 20℃ for 2 h, centrifuge to obtain the precipitate, wash the precipitate with pure water and freeze dry under vacuum to obtain lignin extract; (2) Dissolve 0.5 g of lignin extract and 0.25 g of 4-dimethylaminopyridine in 20 mL of dimethylformamide, add 0.5 g of 2-bromoisobutyryl bromide dropwise under an ice-water bath at 4 °C, and then react at room temperature for 24 h. Then pour the reaction system into 300 mL of distilled water to obtain a precipitate. After centrifuging the precipitate, freeze dry it under vacuum to obtain a macromolecular initiator. (3) Dissolve 200 mg of macromolecular initiator in 10 mL of deionized water, add 20 mg of copper bromide, 40 mg of pentamethyldiethylenetriamine and 140 mg of ascorbic acid to the system under nitrogen protection, and then add 4.0 g of methacryloyloxyethyltrimethylammonium chloride to the above reaction system. The polymerization reaction is carried out at 70°C in an oil bath for 3 h. After the reaction is completed, cool to room temperature, precipitate the reaction product with acetone, wash the reaction product with anhydrous ethanol and deionized water, and freeze dry under vacuum to obtain paper pulp residue-based organic polymer flocculant.

2. A paper pulp residue-based organic polymer flocculant obtained by the preparation method according to claim 1.

3. The application of the paper pulp residue-based organic polymer flocculant of claim 2 in the removal of antibiotics from wastewater.

4. The application according to claim 3, characterized in that, The antibiotic is tetracycline, levofloxacin, or norfloxacin; the dosage of the paper pulp residue-based organic polymer flocculant in the wastewater is 5-20 mg / L.

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