A method for preparing pulp-based organic high molecular weight flocculant by microbubble interface strengthening method and its product and application

Abstract

The present invention proposes a method for preparing pulp-based organic high-molecular-weight flocculants using a microbubble interface enhancement method, as well as its products and applications, belonging to the technical fields of solid waste resource utilization and water treatment agents. The present invention mixes papermaking pulp with nitric acid, then heats and stirs the mixture. After adjusting the pH to a weakly acidic state, a cellulose mixture is obtained. The cellulose mixture is heated, nitrogen is introduced into the cellulose mixture using a microbubble interface enhancement method, and disodium peroxyethylenediaminetetraacetic acid and potassium peroxydisulfate are added. A methacryloyloxyethyltrimethylammonium chloride solution is then added dropwise, followed by potassium peroxydisulfate for reaction. After the reaction is completed, the mixture is cooled to room temperature, purified, frozen, and dried to obtain a pulp-based organic high-molecular-weight flocculant. The above-mentioned flocculant is more effective than other cellulose-based flocculants in removing negatively charged antibiotics, has a wide range of applications, and can achieve an antibiotic removal rate of over 50% at a dosage of approximately 2.0 mg / L.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization and water treatment agents, and in particular relates to a method for preparing a pulp-based organic high-molecular-weight flocculant using a microbubble interface enhancement method, and a product and application thereof. Background Art

[0002] Coagulation has been widely used in water treatment due to its advantages such as low investment and operating costs and simple operation and management. However, traditional inorganic coagulants are poorly effective in removing antibiotics from water. Theoretically, based on the chemical structure and properties of organic pollutants, regulating the functional groups and molecular structure of organic polymer flocculants can enhance the interaction between flocculants and antibiotic pollutants, thereby achieving efficient removal of antibiotic pollutants from water.

[0003] In recent years, in order to enhance the efficiency of coagulation in removing organic pollutants from water bodies, people have used natural organic matter such as chitosan and starch as carriers, and developed a variety of functional organic polymer flocculants through chemical modification methods such as reduction, oxidation, etherification, sulfonation, condensation and grafting copolymerization, achieving effective coagulation and sedimentation separation of organic pollutants from water bodies. The main reasons why functionalized organic polymer flocculants are so effective in removing organic pollutants from water can be attributed to the following two factors: i) The functional groups (such as amine, amide, and aromatic groups) of organic polymer flocculants can adsorb organic pollutants on their surfaces through electrostatic attraction, hydrogen bonding, hydrophobic association, or nonspecific van der Waals forces, reducing the hydrophilicity of organic pollutants and disrupting their stability, thereby enabling the transfer of organic pollutants from the aqueous phase to the solid phase of the flocculents; ii) Due to their larger skeletons, longer molecular chains, and stronger adsorption and bridging abilities, the resulting "flocculant-pollutant" complexes meet the requirements of serving as mesoscale condensation nuclei, further aggregating to form flocs with excellent settling properties, ultimately achieving the separation of organic pollutants from water. Therefore, strengthening the interaction between the functional groups of organic polymer flocculants and organic pollutants, and regulating and optimizing the molecular structure of organic polymer flocculants, are key factors in improving the removal efficiency of organic pollutants.

[0004] Currently, most paper mills primarily use wood pulp as their raw material, generating a significant amount of pulp residue during the papermaking process. Wood pulp papermaking residue is rich in biomass, containing approximately 70% organic matter (cellulose, lignin, and hemicellulose), and contains very low (trace amounts) heavy metals, making it a valuable biomass resource. Therefore, utilizing the organic matter in papermaking residue as raw material, chemically modifying it to produce a novel biomass-based organic polymer flocculant for the removal of antibiotics from water bodies, represents a novel approach to the comprehensive resource utilization of papermaking residue. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a method for preparing pulp-based organic high molecular weight flocculant by microbubble interface strengthening method, as well as its product and application.

[0006] To achieve the above object, the present invention provides a method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method, comprising the following steps:

[0007] The papermaking pulp residue is mixed with nitric acid, heated and stirred, and the pH is adjusted to a weakly acidic state to obtain a cellulose mixed solution. The cellulose mixed solution is heated, nitrogen is introduced into the cellulose mixed solution using a microbubble interface strengthening method, and disodium peroxyethylenediaminetetraacetic acid and potassium peroxydisulfate are added as initiators to initiate a graft copolymerization reaction between cellulose and methacryloyloxyethyltrimethylammonium chloride. Subsequently, a methacryloyloxyethyltrimethylammonium chloride solution is added dropwise, and potassium peroxydisulfate is added again to react. After the reaction is completed, the mixture is cooled to room temperature, purified, frozen, and dried to obtain the pulp residue-based organic high molecular weight flocculant.

[0008] Preferably, the ratio of the papermaking pulp residue to the nitric acid is 1 g:50 mL.

[0009] Preferably, the papermaking pulp residue is mixed with nitric acid and heated and stirred at a temperature of 90 to 100° C., and the stirring time is 6 to 8 hours.

[0010] The addition of nitric acid can digest papermaking pulp residue and remove other substances besides cellulose.

[0011] Preferably, a NaOH solution with a concentration of 0.1 mol / L is used to adjust the pH to 4.8-5.2.

[0012] The term "microbubble interface enhancement method" is a method of introducing micron-sized bubbles to enhance the gas / liquid, liquid / liquid or gas / liquid / solid interface by breaking the diameter of gas or liquid phase particles into micron-sized range, thereby exponentially increasing the mass transfer area and total mass transfer efficiency between gas / liquid and liquid / liquid. Preferably, the aeration volume of the microbubble interface enhancement method is 1.5m 3 / h, the aeration time is 20-40min, the heating temperature of the cellulose mixture during aeration is 65-75℃, and the aeration head is cylindrical.

[0013] The flocculant is prepared using the microbubble interface enhancement method, in which microporous aeration drives water turbulence, causing a large number of microbubbles to appear in the cellulose mixture. This in turn causes the cellulose to react with methacryloyloxyethyltrimethylammonium chloride at the gas-liquid microinterface of the nitrogen microbubbles. The resulting flocculant has a high charge density, large flocs, a large molecular weight, and a branched long-chain structure.

[0014] Preferably, the mass ratio of the total mass of the potassium persulfate to the papermaking pulp residue is (0.02-0.1):2, the mass ratio of the disodium peroxyethylenediaminetetraacetic acid to the papermaking pulp residue is (0.05-0.1):2, and the usage ratio of the papermaking pulp residue to the methacryloyloxyethyltrimethylammonium chloride solution is 2g:(10-30)mL.

[0015] Furthermore, the mass ratio of the potassium peroxodisulfate added for the first time to the potassium peroxodisulfate added for the second time is 1:1.

[0016] Preferably, the mass concentration of the methacryloyloxyethyltrimethylammonium chloride solution is 75 wt %, the reaction temperature after the methacryloyloxyethyltrimethylammonium chloride solution is added is 70° C., and the stirring reaction time is 2 to 6 hours.

[0017] Preferably, the reagent used for purification is acetone, and the drying is vacuum drying at a drying temperature of 60°C.

[0018] The present invention also provides a pulp-based organic high molecular weight flocculant prepared by the above method, wherein the pulp-based organic high molecular weight flocculant has a Zeta potential of 64.3-73.2 mV, a charge density of 4700-4950 μeq / L, and a molecular weight of 90000 kDa-100000 kDa.

[0019] The present invention also proposes the use of the pulp-based organic high-molecular-weight flocculant in the treatment of antibiotic wastewater.

[0020] Preferably, the dosage of the pulp-based organic high molecular weight flocculant in the antibiotic wastewater is 0.4 to 2.4 mg / L.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] 1. The present invention utilizes cellulose in papermaking pulp residue and reacts it with methacryloyloxyethyltrimethylammonium chloride monomer in the presence of initiators such as disodium peroxyethylenediaminetetraacetic acid and potassium disulfate in a fully aerated environment. A microbubble interface enhancement method is used to cause a graft copolymerization reaction between the cellulose and the nitrogen microbubbles of methacryloyloxyethyltrimethylammonium chloride at the gas-liquid microinterface to generate a macromolecular copolymer with a branched structure. The obtained flocculant has a high charge density, a large molecular weight, and a branched long-chain structure. This structure causes the flocculant of the present invention to generate large flocs, which have a greater chance of contact with pollutant particles and a better adsorption and bridging effect on tiny flocs than traditional flocculants. At the same time, the flocculant has a high charge density, so it has a stronger adsorption and electrical neutralization ability, has an excellent removal effect on antibiotics in water, has the advantages of high flocculation efficiency and ease of purification, and is suitable for the field of wastewater treatment.

[0023] 2. The flocculant prepared by the preparation method of the present invention has a Zeta potential of 73.2 mV, a charge density of 5030 μeq / L, a molecular weight of about 90,000 kDa to 100,000 kDa, a strong electrical neutralization ability, a high charge density, and is better than other cellulose-based flocculants in removing negatively charged antibiotics, and has a wide range of applications.

[0024] 3. The flocculation efficiency of the flocculant product obtained by the present invention is better than that of the flocculant products in the prior art. When the dosage is about 2.0 mg / L, the antibiotic removal rate can reach more than 50%.

[0025] 4. The preparation method of the present invention has a simple production process, few by-products, and requires few equipment, 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 rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

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

[0028] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. 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. 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 any conflict with any incorporated document, the contents 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 described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative 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 embodiment of the present invention provides a method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface enhancement method, comprising the following steps:

[0032] The papermaking pulp residue is mixed with nitric acid, heated and stirred, and the pH is adjusted to a weakly acidic state to obtain a cellulose mixed solution. The cellulose mixed solution is heated, nitrogen is introduced into the cellulose mixed solution using a microbubble interface strengthening method, and disodium peroxyethylenediaminetetraacetic acid and potassium peroxydisulfate are added as initiators to initiate a graft copolymerization reaction between cellulose and methacryloyloxyethyltrimethylammonium chloride; then, a methacryloyloxyethyltrimethylammonium chloride solution is added dropwise, and potassium peroxydisulfate is added again to terminate the reaction. After the reaction is completed, the mixture is cooled to room temperature, purified, frozen, and dried to obtain the pulp residue-based organic high molecular weight flocculant.

[0033] In a preferred embodiment of the present invention, the ratio of the papermaking pulp residue to the nitric acid is 1 g:50 mL.

[0034] In a preferred embodiment of the present invention, the papermaking pulp residue is mixed with nitric acid and heated and stirred at a temperature of 90 to 100° C. for a stirring time of 6 to 8 hours.

[0035] In a preferred embodiment of the present invention, a NaOH solution with a concentration of 0.1 mol / L is used to adjust the pH to 4.8-5.2.

[0036] In a preferred embodiment of the present invention, the aeration volume of the microbubble interface enhancement method is 1.5m 3 / h, the aeration time is 20-40min, the heating temperature of the cellulose mixture during aeration is 65-75℃, and the aeration head is cylindrical.

[0037] Too much aeration will cause too many bubbles in the solution and incomplete reaction; too little aeration will cause a small amount of oxygen to remain in the reaction system, causing the reaction to fail, and too little aeration will lead to uneven reaction.

[0038] The cylindrical aeration head can make the aeration area larger and the aeration more complete, while the spherical aeration head will lead to insufficient aeration.

[0039] In a preferred embodiment of the present invention, the mass ratio of the total mass of potassium persulfate to papermaking pulp residue is (0.02-0.1):2, the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is (0.05-0.1):2, and the usage ratio of the papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution is 2 g:(10-30) mL.

[0040] In a preferred embodiment of the present invention, the mass ratio of the potassium peroxodisulfate added for the first time to the potassium peroxodisulfate added for the second time is 1:1.

[0041] Potassium peroxydisulfate is the initiator of the grafting reaction. Too much or too little potassium peroxydisulfate will make the grafting reaction incomplete. When potassium peroxydisulfate is added twice, the grafting reaction success rate is the highest and the antibiotic removal rate is the highest.

[0042] The purpose of adding disodium tetraacetic acid is to complex the metal ions in the solution. If too little is added, metal ions will still remain in the solution, and if too much is added, subsequent reactions will be interfered with.

[0043] Adding too little methacryloyloxyethyltrimethylammonium chloride will result in too low a grafting rate and failure in the preparation of the coagulant. Adding too much will cause self-polymerization of methacryloyloxyethyltrimethylammonium chloride and failure in the preparation of the coagulant.

[0044] In a preferred embodiment of the present invention, the mass concentration of the methacryloyloxyethyltrimethylammonium chloride solution is 75 wt %, the reaction temperature after the methacryloyloxyethyltrimethylammonium chloride solution is added is 70° C., and the stirring reaction time is 2 to 6 hours.

[0045] In a preferred embodiment of the present invention, the reagent used for purification is acetone, the drying is vacuum drying, and the drying temperature is 60°C.

[0046] The embodiment of the present invention also provides a pulp-based organic high molecular weight flocculant prepared by the above method, wherein the pulp-based organic high molecular weight flocculant has a Zeta potential of 64.3-73.2 mV, a charge density of 4700-4950 μeq / L, and a molecular weight of 90000 kDa-100000 kDa.

[0047] The papermaking pulp residue used in the embodiment of the present invention is papermaking sludge produced in the dry alkaline papermaking production process, with a pH value of ~6.62, an ash content of ~34wt%, an organic matter content of ~66wt%, a lignin content of ~45wt%, a cellulose content of ~10wt%, and a residue rate of ~62wt%.

[0048] The preparation method of the simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) in the application example of the present invention comprises the following steps:

[0049] Weigh 0.05 g of sulfamethoxazole and dissolve it in 0.5 L of water. Stir evenly to obtain the antibiotic stock solution. Take 70 mL of the antibiotic stock solution and dissolve it in 7 L of tap water for subsequent experiments. The concentration, pH and Zeta potential of the experimental water sample were measured to be 1 mg / L, 7.05±0.02 and -10.2±0.5 mV, respectively.

[0050] The final effluent treatment effect of simulated antibiotic wastewater is expressed as antibiotic removal rate (%).

[0051] The raw materials used in the examples of the present invention are all commercially available.

[0052] The technical solution of the present invention is further illustrated by the following examples.

[0053] Examples 1 to 6

[0054] A method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method comprises the following steps:

[0055] (1) Pulp residue was added to 15 wt% nitric acid at a ratio of 1 g to 50 mL, heated to 95°C, and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was complete, the supernatant was discarded and the precipitated portion was washed with ultrasonically treated deionized water. This step was repeated until the mixed solution became milky white.

[0056] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a cellulose mixed solution;

[0057] (3) The cellulose mixture was heated to 70°C, and nitrogen was introduced into the cellulose mixture using a cylindrical microporous aeration head by microbubble interface enhancement method to remove the air in the cellulose mixture and fill the cellulose mixture with nitrogen microbubbles. The aeration was continued for 30 minutes with an aeration volume of 1.5 m 3 / h;

[0058] (4) adding disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is 0.05:2) and potassium peroxydisulfate to the system obtained in step (3), reacting for 30 minutes, then adding dropwise a 75wt% methacryloyloxyethyltrimethylammonium chloride solution, then adding potassium peroxydisulfate, and stirring at 70°C for 5 hours, wherein the total mass ratio of the potassium peroxydisulfate added twice to the papermaking pulp residue is 0.05:2, and the mass ratio of the potassium peroxydisulfate added for the first time to the potassium peroxydisulfate added for the second time is 1:1;

[0059] (5) After the above reaction is completed, the mixture is cooled to room temperature, purified with acetone, frozen, and vacuum-dried at 60°C to obtain a pulp-based organic high molecular weight flocculant.

[0060] Based on the above method, the dosage ratio of papermaking pulp residue and methacryloyloxyethyltrimethylammonium chloride solution was changed to 2g:2mL, 2g:5mL, 2g:10mL, 2g:15mL, 2g:20mL, and 2g:30mL, respectively, to obtain Examples 1 to 6. The flocculants obtained in Examples 1 to 6 were subjected to Zeta potential testing, and the results are shown in Table 1.

[0061] Table 1 Zeta potential test results of flocculants in Examples 1 to 6

[0062]

[0063] Application Example 1

[0064] The flocculants obtained in Examples 1 to 6 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 2.

[0065] Table 2 Results of determination of antibiotic removal rate (%) of flocculants in Examples 1 to 6

[0066]

[0067] Note: The “-0.8” in the table is due to data differences caused by instrument errors, which actually means that the antibiotic removal rate is almost 0.

[0068] Combining Table 1 and Table 2, it can be seen that the dosage ratio of papermaking pulp residue and methacryloyloxyethyltrimethylammonium chloride solution directly affects the potential of the flocculant and the antibiotic removal rate. When the dosage ratio of the two is 2g:10mL, the antibiotic removal effect is the best. The reason is that if the addition amount of methacryloyloxyethyltrimethylammonium chloride is too small, the grafting rate will be too low and the coagulant preparation will fail. If the addition amount is too high, methacryloyloxyethyltrimethylammonium chloride will self-polymerize and the coagulant preparation will fail.

[0069] Examples 7 to 12

[0070] A method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method comprises the following steps:

[0071] (1) Pulp residue was added to 15 wt% nitric acid at a ratio of 1 g to 50 mL, heated to 95°C, and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was complete, the supernatant was discarded and the precipitated portion was washed with ultrasonically treated deionized water. This step was repeated until the mixed solution became milky white.

[0072] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a cellulose mixed solution;

[0073] (3) The cellulose mixture was heated to 70°C, and nitrogen was introduced into the cellulose mixture using a cylindrical microporous aeration head by microbubble interface enhancement method to remove the air in the cellulose mixture and fill the cellulose mixture with nitrogen microbubbles. The aeration was continued for 30 minutes with an aeration volume of 1.5 m 3 / h;

[0074] (4) adding disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is (0.05:2) and potassium peroxydisulfate to the system obtained in step (3), reacting for 30 minutes, then adding a 75 wt% methacryloyloxyethyltrimethylammonium chloride solution dropwise according to the amount ratio of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution of 2 g:10 mL, then adding potassium peroxydisulfate, stirring at 70° C. for 5 hours, wherein the mass ratio of the first added potassium peroxydisulfate to the second added potassium peroxydisulfate is 1:1;

[0075] (5) After the above reaction is completed, the mixture is cooled to room temperature, purified with acetone, frozen, and vacuum-dried at 60°C to obtain a pulp-based organic high molecular weight flocculant.

[0076] Based on the above method, the mass ratio of the total mass of potassium persulfate to papermaking pulp residue was changed to 5 mg:2 g, 10 mg:2 g, 15 mg:2 g, 20 mg:2 g, 50 mg:2 g, and 100 mg:2 g, respectively, to obtain Examples 7 to 12. The flocculants obtained in Examples 7 to 12 were subjected to Zeta potential tests, and the results are shown in Table 3.

[0077] Table 3 Zeta potential test results of flocculants in Examples 7 to 12

[0078]

[0079] Application Example 2

[0080] The flocculants obtained in Examples 7 to 12 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to determine the antibiotic removal rate. The results are shown in Table 4.

[0081] Table 4 Determination results of antibiotic removal rate (%) of flocculants in Examples 7 to 12

[0082]

[0083] It can be seen from Tables 3 and 4 that when the dosage of potassium peroxodisulfate is 50 mg, the zeta potential of the flocculant is the highest, and the antibiotic removal rate of the flocculant is the highest. This is mainly because potassium peroxodisulfate is the initiator of the grafting reaction. Too low or too high an initiator dosage will affect the grafting reaction, resulting in a lower grafting rate, a lower zeta potential, and a worse flocculation effect.

[0084] Examples 13 to 18

[0085] A method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method comprises the following steps:

[0086] (1) Pulp residue was added to 15 wt% nitric acid at a ratio of 1 g to 50 mL, heated to 95°C, and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was complete, the supernatant was discarded and the precipitated portion was washed with ultrasonically treated deionized water. This step was repeated until the mixed solution became milky white.

[0087] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a cellulose mixed solution;

[0088] (3) The cellulose mixture was heated to 70°C, and nitrogen was introduced into the cellulose mixture using a cylindrical microporous aeration head by microbubble interface enhancement method to remove the air in the cellulose mixture and fill the cellulose mixture with nitrogen microbubbles. The aeration was continued for 30 minutes with an aeration volume of 1.5 m 3 / h;

[0089] (4) adding disodium peroxyethylenediaminetetraacetic acid and potassium peroxydisulfate to the system obtained in step (3), reacting for 30 minutes, then adding dropwise a 75 wt% methacryloyloxyethyltrimethylammonium chloride solution according to a ratio of 2 g:10 mL of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution, then adding potassium peroxydisulfate, and stirring at 70° C. for 5 hours, wherein the total mass ratio of the potassium peroxydisulfate added twice to the papermaking pulp residue is 0.05:2, and the mass ratio of the potassium peroxydisulfate added for the first time to the potassium peroxydisulfate added for the second time is 1:1;

[0090] (5) After the above reaction is completed, the mixture is cooled to room temperature, purified with acetone, frozen, and vacuum-dried at 60°C to obtain a pulp-based organic high molecular weight flocculant.

[0091] Based on the above method, the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue was changed to 5 mg: 2 g, 10 mg: 2 g, 15 mg: 2 g, 20 mg: 2 g, 50 mg: 2 g, and 100 mg: 2 g, respectively, to obtain Examples 13 to 18. The flocculants obtained in Examples 13 to 18 were subjected to Zeta potential testing, and the results are shown in Table 5.

[0092] Table 5 Zeta potential test results of flocculants in Examples 13 to 18

[0093]

[0094] Application Example 3

[0095] The flocculants obtained in Examples 13 to 18 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 6.

[0096] Table 6 Determination results of antibiotic removal rate (%) of flocculants in Examples 13 to 18

[0097]

[0098]

[0099] It can be seen from Tables 5 and 6 that when the addition amount of EDTA disodium salt is 50 mg, the flocculant zeta potential is the highest and the antibiotic removal rate is also the highest. This is because the role of EDTA disodium salt in the solution is to complex the metal ions in the solution. If too little is added, there will still be residual metal ions in the solution, and if too much is added, it will interfere with subsequent reactions.

[0100] Example 19

[0101] A method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method comprises the following steps:

[0102] (1) Pulp residue was added to 15 wt% nitric acid at a ratio of 1 g to 50 mL, heated to 95°C, and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was complete, the supernatant was discarded and the precipitated portion was washed with ultrasonically treated deionized water. This step was repeated until the mixed solution became milky white.

[0103] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a cellulose mixed solution;

[0104] (3) The cellulose mixture was heated to 70°C, and nitrogen was introduced into the cellulose mixture using a cylindrical microporous aeration head by microbubble interface enhancement method to remove the air in the cellulose mixture and fill the cellulose mixture with nitrogen microbubbles. The aeration was continued for 30 minutes with an aeration volume of 1.5 m 3 / h;

[0105] (4) adding disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is 0.05:2) and potassium peroxydisulfate to the system obtained in step (3), reacting for 30 minutes, then adding methacryloyloxyethyltrimethylammonium chloride solution with a mass concentration of 75wt% dropwise according to the amount ratio of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution of 2g:10mL, adding potassium peroxydisulfate again, stirring and reacting at 70°C for 5 hours, wherein the total mass ratio of potassium peroxydisulfate added twice to papermaking pulp residue is 0.05g:2, and the mass ratio of the first added potassium peroxydisulfate to the second added potassium peroxydisulfate is 1:1;

[0106] (5) After the above reaction is completed, the mixture is cooled to room temperature, purified with acetone, frozen, and vacuum-dried at 60°C to obtain a pulp-based organic high molecular weight flocculant.

[0107] Comparative Example 1

[0108] Same as Example 19, except that step (3) is specifically as follows:

[0109] The cellulose mixture was heated to 70° C., the container was filled with nitrogen, and then sealed. The container was then stirred at 300 r / min for 30 min.

[0110] The flocculants obtained in Example 19 and Comparative Example 1 were subjected to Zeta potential tests. The results are shown in Table 7.

[0111] Table 7 Zeta potential test results of flocculants in Example 19 and Comparative Example 1

[0112]

[0113] Application Example 4

[0114] The flocculants obtained in Example 19 and Comparative Example 1 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 8.

[0115] Table 8 Determination results of flocculant antibiotic removal rate (%) of Example 19 and Comparative Example 1

[0116]

[0117] It can be seen from the data results in Tables 7 and 8 that after the aeration conditions in step (3) of Example 19 were changed to stirring, the zeta potential of the flocculant and the antibiotic removal rate were both reduced. This is because aeration can form a large number of microbubbles in the solution, so that the grafting reaction of cellulose and methacryloyloxyethyltrimethylammonium chloride occurs at the gas-liquid microinterface, making the reaction more complete and improving the grafting rate.

[0118] Example 20

[0119] A method for preparing a pulp-based organic high molecular weight flocculant by a microbubble interface strengthening method comprises the following steps:

[0120] (1) Pulp residue was added to 15 wt% nitric acid at a ratio of 1 g to 50 mL, heated to 95°C, and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was complete, the supernatant was discarded and the precipitated portion was washed with ultrasonically treated deionized water. This step was repeated until the mixed solution became milky white.

[0121] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a cellulose mixed solution;

[0122] (3) The cellulose mixture was heated to 70°C, and nitrogen was introduced into the cellulose mixture using a cylindrical microporous aeration head by microbubble interface enhancement method to remove the air in the cellulose mixture and fill the cellulose mixture with nitrogen microbubbles. The aeration was continued for 30 minutes with an aeration volume of 1.5 m 3 / h;

[0123] (4) adding disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is 0.05:2) and potassium peroxydisulfate to the system obtained in step (3), reacting for 30 minutes, then adding dropwise a 75 wt% methacryloyloxyethyltrimethylammonium chloride solution according to the amount ratio of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution of 2 g:10 mL, adding potassium peroxydisulfate again, stirring and reacting at 70° C. for 5 hours, wherein the total mass ratio of potassium peroxydisulfate added twice to papermaking pulp residue is 0.05:2, and the mass ratio of the first added potassium peroxydisulfate to the second added potassium peroxydisulfate is 1:1;

[0124] (5) After the above reaction is completed, the mixture is cooled to room temperature, purified with acetone, frozen, and vacuum-dried at 60°C to obtain a pulp-based organic high molecular weight flocculant.

[0125] Comparative Example 2

[0126] The same as Example 20, except that the order of adding potassium persulfate is changed, and step (4) is specifically as follows:

[0127] Disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is 0.01:2) and potassium peroxydisulfate (the mass ratio of the total mass of potassium peroxydisulfate to papermaking pulp residue is 0.05:2) are added to the system obtained in step (3), and the reaction is carried out for 30 minutes. Then, a 75wt% methacryloyloxyethyltrimethylammonium chloride solution is added dropwise according to the amount ratio of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution of 2g:10mL, and the reaction is stirred at 70°C for 5 hours.

[0128] Comparative Example 3

[0129] Same as Example 20, except that step (4) is specifically as follows:

[0130] To the system obtained in step (3), disodium peroxyethylenediaminetetraacetic acid (the mass ratio of disodium peroxyethylenediaminetetraacetic acid to papermaking pulp residue is 0.01:2), potassium peroxydisulfate (the mass ratio of the total mass of potassium peroxydisulfate to papermaking pulp residue is 0.05:2) and a 75 wt% methacryloyloxyethyltrimethylammonium chloride solution (the amount ratio of papermaking pulp residue to methacryloyloxyethyltrimethylammonium chloride solution is 2 g:10 mL) were added, and the mixture was stirred at 70°C for 5 h.

[0131] The flocculants obtained in Example 20 and Comparative Examples 2-3 were subjected to Zeta potential tests. The results are shown in Table 9.

[0132] Table 9 Zeta potential test results of flocculants in Example 20 and Comparative Examples 2-3

[0133]

[0134] Application Example 5

[0135] The flocculants obtained in Example 20 and Comparative Examples 2-3 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 10.

[0136] Table 10 Determination results of antibiotic removal rate (%) of flocculants in Example 20 and Comparative Examples 2-3

[0137]

[0138] It can be seen from Tables 9 and 10 that the order of adding potassium peroxodisulfate is related to the performance of the flocculant. Potassium peroxodisulfate is the initiator of the grafting reaction. When the dosage of potassium peroxodisulfate is 50 mg and it is added before or after the addition of methacryloyloxyethyltrimethylammonium chloride, the zeta potential of the flocculant is the highest, and the antibiotic removal rate of the flocculant is the highest. Changing the dosage and addition order of the initiator will affect the grafting reaction, resulting in a lower grafting rate, a lower zeta potential, and a worse flocculation effect.

[0139] Comparative Example 4

[0140] Same as Example 20, except that in step (3), the aeration rate is 1.0m 3 / h.

[0141] Comparative Example 5

[0142] Same as Example 20, except that in step (3), the aeration rate is 2.0m 3 / h.

[0143] The flocculants obtained in Example 20 and Comparative Examples 4-5 were subjected to Zeta potential tests. The results are shown in Table 11.

[0144] Table 11 Zeta potential test results of flocculants in Example 20 and Comparative Examples 4-5

[0145]

[0146] Application Example 6

[0147] The flocculants obtained in Example 20 and Comparative Examples 4-5 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 12.

[0148] Table 12 Determination results of antibiotic removal rate (%) of flocculants in Example 20 and Comparative Examples 4-5

[0149]

[0150] It can be seen from Tables 11 and 12 that both increasing and decreasing the aeration volume will lead to a decrease in the flocculant zeta potential and the antibiotic removal rate. This is because too low an aeration volume will cause the solution to not be completely anaerobic, and the bubble content in the solution is too low, which cannot enable the grafting reaction to occur at the gas-liquid microinterface, resulting in incomplete reaction; too high an aeration volume will cause excessive and large bubbles in the solution, resulting in reaction failure.

[0151] Comparative Example 6

[0152] The same as Example 20, except that, in step (3), nitrogen is introduced into the cellulose mixed solution using a spherical microporous aeration head.

[0153] The flocculants obtained in Example 20 and Comparative Example 6 were subjected to Zeta potential tests. The results are shown in Table 13.

[0154] Table 13 Zeta potential test results of flocculants in Example 20 and Comparative Example 6

[0155]

[0156] Application Example 7

[0157] The flocculants obtained in Example 20 and Comparative Example 6 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 14.

[0158] Table 14 Determination results of flocculant antibiotic removal rate (%) of Example 20 and Comparative Example 6

[0159]

[0160] It can be seen from Table 13 and Table 14 that the cylindrical aerator head can make the aeration area larger and the aeration more sufficient, while the spherical aerator head is prone to insufficient aeration.

[0161] Comparative Example 7

[0162] The same as Example 20, except that the 75 wt % methacryloyloxyethyltrimethylammonium chloride solution is replaced by an equal volume of the 75 wt % polyacrylamide solution.

[0163] Application Example 8

[0164] The flocculant obtained in Comparative Example 7 was added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 15.

[0165] Table 15 Comparative Example 7 Flocculant Antibiotic Removal Rate (%) Determination Results

[0166]

[0167] As shown in Table 15, compared with the coagulation effluent indicators of the flocculant in Comparative Example 7, the antibiotic removal rate of the cellulose-based cationic organic polymer flocculant in Example 20 of the present invention for papermaking pulp residue was significantly improved, with the removal rate increasing by up to 21.6% at the same dosage. This indicates that the flocculant in the present invention has a higher charge density, a stronger charge neutralization effect, and a more pronounced coagulation effect.

[0168] Comparative Example 8

[0169] Same as Example 20, except that, in step (2), a high-flow nitrogen gas is introduced into the container through a vent pipe. Specifically, the cellulose mixed solution is heated to 70°C, and a high-flow nitrogen gas is introduced into the cellulose mixed solution. The nitrogen gas is continuously introduced for 30 minutes, and the aeration volume is 1.5m 3 / h.

[0170] Comparative Example 9

[0171] The same as Example 20, except that: (1) papermaking pulp residue was added to deionized water at a ratio of 1 g to 50 mL, heated to 95° C., and stirred for 7 h. The heated solution was placed in a beaker and allowed to settle. After the precipitation was completed, the supernatant was discarded, and the precipitated portion was washed with ultrasonicated deionized water. This step was repeated until the mixed solution became milky white.

[0172] (2) adjusting the pH of the mixed solution to 5.0 using a 0.1 mol / L NaOH solution so that the cellulose is suspended in the mixed solution to obtain a lignin mixed solution;

[0173] The remaining steps are the same as in Example 20.

[0174] Application Example 9

[0175] The flocculants obtained in Comparative Examples 8 and 9 were added to simulated antibiotic wastewater (1 mg / L sulfamethoxazole solution) at different dosages to measure the antibiotic removal rate. The measurement results are shown in Table 16.

[0176] Table 16 Comparative Examples 8 and 9 Flocculant Antibiotic Removal Rate (%) Determination Results

[0177]

[0178] According to Table 16, it can be seen that high-speed nitrogen flow instead of aeration cannot provide better reaction conditions, resulting in a lower antibiotic removal rate of the flocculant; the effect of water on extracting cellulose from paper pulp residue is worse than nitric acid, so the effect of the prepared flocculant on removing antibiotics is also worse.

[0179] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. Application of pulp-based organic high molecular weight flocculant in the treatment of antibiotic wastewater, characterized in that: The dosage of the pulp-based organic high molecular weight flocculant in the antibiotic wastewater is 0.4-2.4 mg / L; The pulp-based organic high molecular weight flocculant is prepared by a microbubble interface enhancement method, comprising the following steps: The papermaking pulp residue is mixed with nitric acid, heated and stirred, and the pH is adjusted to a weakly acidic state to obtain a cellulose mixed solution. The cellulose mixed solution is heated, nitrogen is introduced into the cellulose mixed solution using a microbubble interface enhancement method, and disodium ethylenediaminetetraacetic acid and potassium peroxodisulfate are added as initiators to initiate a graft copolymerization reaction between cellulose and methacryloyloxyethyltrimethylammonium chloride. Then, a methacryloyloxyethyltrimethylammonium chloride solution is added dropwise, and potassium peroxodisulfate is added again for reaction. The mixture is cooled to room temperature, purified, frozen, and dried to obtain the pulp residue-based organic high molecular weight flocculant. The papermaking pulp residue is mixed with nitric acid and heated and stirred at a temperature of 90 to 100° C. for 6 to 8 hours; The pH is adjusted to be weakly acidic by using a 0.1 mol / L NaOH solution to adjust the pH to 4.8-5.2; The aeration volume of the microbubble interface enhancement method is 1.5m 3 / h, the aeration time is 20-40min, the heating temperature of the cellulose mixture during aeration is 65-75℃, and the aeration head is cylindrical; The pulp residue-based organic high molecular weight flocculant has a Zeta potential of 64.3-73.2 mV, a charge density of 4700-4950 μeq / L, and a molecular weight of 90000 kDa-100000 kDa.

2. The use of the pulp-based organic high molecular weight flocculant in the treatment of antibiotic wastewater according to claim 1, characterized in that: The usage ratio of the papermaking pulp residue to the nitric acid is 1 g:50 mL.

3. The use of the pulp-based organic high molecular weight flocculant in the treatment of antibiotic wastewater according to claim 1, characterized in that: The mass ratio of the total mass of the potassium persulfate to the papermaking pulp residue is (0.02-0.1):2, the mass ratio of the disodium ethylenediaminetetraacetic acid to the papermaking pulp residue is (0.05-0.1):2, and the usage ratio of the papermaking pulp residue to the methacryloyloxyethyltrimethylammonium chloride solution is 2g:(10-30)mL.

4. The use of the pulp-based organic high molecular weight flocculant in the treatment of antibiotic wastewater according to claim 1, characterized in that: The mass concentration of the methacryloyloxyethyltrimethylammonium chloride solution is 75 wt %. After the methacryloyloxyethyltrimethylammonium chloride solution is added, the reaction temperature is 70° C., and the stirring reaction time is 2 to 6 hours.

Images