Cationic etherifying agent composition for sewage treatment and preparation method thereof

Abstract

The invention relates to the technical field of sewage treatment, and discloses a cationic etherifying agent composition for sewage treatment and a preparation method thereof. The invention obtains a cationic etherifying agent composition for sewage treatment by mixing gemini imidazoline quaternary ammonium salt etherified starch, chitosan-based grafted modified copolymer and polyaluminium silicate. The nitrogen atoms, hydroxyl groups and amino groups on the imidazoline ring and the pyrrole ring can form hydrogen bonds during the flocculation process, thereby enhancing the interaction between the composition and the colloidal particles and improving the flocculation effect; the positive charge in the quaternary ammonium salt can react with the negative charge carried by the suspended particles in the sewage, thereby making the particles more easily aggregated and improving the flocculation performance; the chitosan and starch molecular chains are relatively long, and multiple pollutant molecules can be adsorbed at the same time, thus playing a bridging and connecting role; by introducing the gemini imidazoline quaternary ammonium salt structure and the cationic modified pyrrolidone structure into the starch and chitosan molecules, the active sites of the starch and chitosan molecules are increased, thereby enhancing the flocculation effect.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a cationic etherifying agent composition for sewage treatment and a preparation method thereof. Background Art

[0002] Water resources are an important and indispensable natural resource in modern society, and the development of industrialization has made water pollution increasingly serious. Wastewater generated in industrial or agricultural production usually contains various suspended particles, inorganic or organic particles, etc. These particles are small in size and have charges on the surface, making the liquid clarification process difficult. For the treatment of such pollutants, gravity sedimentation, adsorption, oxidation-reduction, coagulation-flocculation, membrane filtration and biochemical technology are usually used for treatment. Among them, one of the most commonly used technologies for achieving solid-liquid separation is flocculation, which promotes its sedimentation and separation by adding compounds that have a flocculating effect on impurities in sewage. It is mainly divided into inorganic flocculants and organic flocculants. Organic flocculants include synthetic polymer flocculants and natural polymer flocculants. Developing new and efficient flocculants, optimizing flocculation process control, and improving their flocculation performance are hot topics in the field of improving organic flocculants. Etherifying agents are a class of chemical substances that can promote the formation of ether compounds. They usually contain active groups, such as hydroxyl or halogenated hydrocarbon groups, which can react with other molecules. Cationic etherifying agents refer to compounds that can introduce cationic groups in chemical reactions. The molecular structure and performance of flocculants can be regulated through etherification modification, and they have broad application prospects in the field of water treatment. In the document "Application of Chitosan Composite Flocculant in Urban Domestic Wastewater Treatment", chitosan composite flocculants prepared by chitosan and other flocculants and additives according to a certain formula and process have important promotion and application value in urban domestic sewage treatment, but their flocculation effect needs to be improved. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the shortcomings of the prior art, the present invention provides a cationic etherifying agent composition for sewage treatment and a preparation method thereof, which has a good flocculation effect on pollutants in sewage.

[0005] (II) Technical solution

[0006] To achieve the above purpose, the present invention provides the following technical solution: a cationic etherifying agent composition for sewage treatment, comprising the following components by weight: 14-22 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 10-15 parts by weight of chitosan-based grafted modified copolymer, and 2-5 parts by weight of polyaluminum silicate.

[0007] Preferably, the method for preparing the gemini imidazoline quaternary ammonium salt etherified starch comprises the following steps:

[0008] (1) Add 10-14 g of oleic acid and 12-18 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 2-5 g of a water-carrying agent, heat to 145-155° C. to react for 3.5-4 h, then heat to 220-230° C. to react for 2-3 h until no water is carried out, and after the reaction is completed, cool to 90-110° C. and remove the unreacted water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0009] (2) adding 17-20 g of the imidazoline intermediate and 7-11 g of dichlorohexane to anhydrous ethanol solvent, stirring and mixing, and then heating to 78-85° C. for reflux reaction. After the reaction is completed, the solvent is removed by distillation under reduced pressure, and acetone is added for recrystallization and purification to obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0010] (3) Stirring and mixing the cationic etherifying agent of gemini imidazoline quaternary ammonium salt and a sodium hydroxide aqueous solution with a mass fraction of 24%-32%, spraying the mixture on the corn starch, mixing thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 178-186 W for 4-10 min. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain gemini imidazoline quaternary ammonium salt etherified starch.

[0011] Preferably, the water-carrying agent in step (1) is xylene.

[0012] Preferably, the reaction time in step (2) is 3-6 hours.

[0013] Preferably, in step (3), the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.14-1.2:2.7-2.8.

[0014] Preferably, the method for preparing the chitosan-based graft-modified copolymer comprises the following steps:

[0015] S1. Add 6-12g of tetramethylammonium chloride and deionized water to a flask, stir at 10-18 ° C for 20-40min to fully dissolve the tetramethylammonium chloride, add 7-15g of 2-methyl-N-(oxirane-2-ylmethyl)propan-2-amine dropwise to the tetramethylammonium chloride solution, keep the reaction at 25-30 ° C for 1-2h, then raise the temperature to 35-42 ° C and continue the reaction for 2.5-4h. After the reaction is completed, cool and distill at atmospheric pressure to obtain a secondary amino cationic etherifying agent;

[0016] S2. 15-22 g of N-vinyl pyrrolidone, 11-14 g of paraformaldehyde, and 0.04-0.07 g of acetic acid catalyst were added to a flask, nitrogen was introduced for 20-35 min to remove oxygen, the temperature was raised to 82-90 ° C, a secondary amino cationic etherifying agent was added thereto, the temperature was raised to 120-140 ° C for 5-9 h, and after the reaction, a cationic modified pyrrolidone was obtained;

[0017] S3. Add 4-8g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1%-1.8%, stir to dissolve, add 2-5g of cationic modified pyrrolidone and 6-10g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 10-15 minutes to remove oxygen, add 0.02-0.08g of initiator, raise the temperature to 55-62°C to react for 2-3.5 hours, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer.

[0018] Preferably, the initiator in S3 is azobisisobutyramidine hydrochloride.

[0019] Preferably, the preparation method of the cationic etherifying agent composition for sewage treatment is: adding gemini imidazoline quaternary ammonium salt etherified starch, chitosan-based grafted modified copolymer, and polyaluminum silicate into a reactor, stirring and mixing at 400-700 rpm for 5-12 minutes to obtain the cationic etherifying agent composition for sewage treatment.

[0020] 3. Beneficial technical effects

[0021] The invention etherifies and graft-modifies starch and chitosan with a homemade cationic etherifying agent to obtain gemini imidazoline quaternary ammonium salt etherified starch and chitosan-based graft-modified copolymer, and then mixes the gemini imidazoline quaternary ammonium salt etherified starch, the chitosan-based graft-modified copolymer and polyaluminium silicate to obtain a cationic etherifying agent composition for sewage treatment.

[0022] Oleic acid and N1-(4-chlorophenyl)ethane-1,2-diamine undergo amidation and cyclization to obtain an imidazoline intermediate, which undergoes a quaternization reaction with dichlorohexane to obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent, and the chlorine in the gemini imidazoline quaternary ammonium salt cationic etherifying agent and the hydroxyl group in starch undergo an etherification reaction to obtain a gemini imidazoline quaternary ammonium salt etherified starch. The quaternary ammonium salt group in tetramethylammonium chloride attacks the epoxy group in 2-methyl-N-(oxirane-2-ylmethyl)propane-2-amine to undergo a ring-opening reaction to obtain a secondary amine cationic etherifying agent and introduce a hydroxyl group. N-vinyl pyrrolidone, polyformaldehyde and the secondary amine group in the secondary amine cationic etherifying agent undergo a Mannich reaction to obtain a cationic modified pyrrolidone and introduce an olefin group. The amino group in chitosan is grafted and copolymerized with the cationic modified pyrrolidone and acrylamide to obtain a chitosan-based grafted modified copolymer.

[0023] The nitrogen atoms on the imidazoline ring and the pyrrole ring as well as the hydroxyl group and the amino group can form hydrogen bonds during the flocculation process. This hydrogen bonding effect helps to enhance the interaction between the composition and the colloidal particles, so that it can be better adsorbed on the surface of the colloidal particles and promote the aggregation of the colloidal particles to improve the flocculation effect; many suspended particles in sewage carry negative charges, and the positive charges carried by the quaternary ammonium salt cations can react with these negative charges to neutralize them, thereby reducing the electrostatic repulsion between the particles, making it easier for the particles to approach each other and aggregate to form larger flocs, thereby improving the flocculation performance; chitosan and starch have longer molecular chains and can adsorb multiple colloidal particles or pollutant molecules at the same time, playing a bridging role between them to form larger flocs and accelerate the sedimentation rate; by introducing the gemini imidazoline quaternary ammonium salt structure and the cationic modified pyrrolidone structure into the starch and chitosan molecules, the active sites of the starch and chitosan molecules are increased, thereby enhancing the flocculation effect. DETAILED DESCRIPTION Example 1

[0024] (1) Add 10 g of oleic acid and 12 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 2 g of xylene water-carrying agent, heat to 145°C for reaction for 3.5 h, then heat to 220°C for reaction for 2 h until no water is carried out, after the reaction is completed, cool to 90°C and remove unreacted xylene water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0025] (2) Add 17 g of the imidazoline intermediate and 7 g of dichlorohexane to anhydrous ethanol solvent, stir and mix, then heat to 78° C. and reflux for 3 h. After the reaction is completed, remove the solvent by distillation under reduced pressure, add acetone for recrystallization and purification, and obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0026] (3) Stirring and mixing a gemini imidazoline quaternary ammonium salt cationic etherifying agent and a sodium hydroxide aqueous solution with a mass fraction of 24%, spraying the mixture on corn starch, wherein the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.14:2.7, mixing the mixture thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 178 W for 4 min. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain gemini imidazoline quaternary ammonium salt etherified starch;

[0027] (4) Add 6 g of tetramethylammonium chloride and deionized water into a flask, stir at 10°C for 20 min to fully dissolve the tetramethylammonium chloride, dropwise add 7 g of 2-methyl-N-(oxiran-2-ylmethyl)propan-2-amine into the tetramethylammonium chloride solution, keep the temperature at 25°C for 1 h, then raise the temperature to 35°C and continue the reaction for 2.5 h. After the reaction is completed, cool and distill at normal pressure to obtain a secondary amino cationic etherifying agent;

[0028] (5) Add 15 g of N-vinyl pyrrolidone, 11 g of polyformaldehyde, and 0.04 g of acetic acid catalyst into a flask, introduce nitrogen for 20 min to remove oxygen, heat to 82 °C, add a secondary amino cationic etherifying agent, heat to 120 °C and react for 5 h. After the reaction is completed, a cationic modified pyrrolidone is obtained;

[0029] (6) Add 4 g of chitosan to a 1% acetic acid aqueous solution, stir to dissolve, add 2 g of cationic modified pyrrolidone and 6 g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 10 min to remove oxygen, add 0.02 g of azobisisobutylamidine hydrochloride initiator, heat to 55 °C to react for 2 h, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer;

[0030] (7) 14 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 10 parts by weight of chitosan-based grafted modified copolymer, and 2 parts by weight of polyaluminium silicate were added into a reactor and stirred at 400 rpm for 5 minutes to obtain a cationic etherifying agent composition for sewage treatment. Example 2

[0031] (1) Add 14 g of oleic acid and 18 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 5 g of xylene water-carrying agent, heat to 155°C for reaction for 4 h, then heat to 230°C for reaction for 3 h until no water is carried out, after the reaction is completed, cool to 110°C and remove unreacted xylene water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0032] (2) Add 20 g of the imidazoline intermediate and 11 g of dichlorohexane to anhydrous ethanol solvent, stir and mix, then heat to 85° C. and reflux for 6 h. After the reaction is completed, remove the solvent by distillation under reduced pressure, add acetone for recrystallization and purification, and obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0033] (3) Stirring and mixing a gemini imidazoline quaternary ammonium salt cationic etherifying agent and a sodium hydroxide aqueous solution with a mass fraction of 32%, spraying the mixture on corn starch, wherein the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.2:2.8, and after fully mixing, placing the mixture in a microwave oven and irradiating it at a power of 186 W for 10 min. After the reaction is completed, washing with anhydrous ethanol, filtering, and drying are performed to obtain gemini imidazoline quaternary ammonium salt etherified starch;

[0034] (4) Add 12 g of tetramethylammonium chloride and deionized water into a flask, stir at 18°C ​​for 40 min to fully dissolve the tetramethylammonium chloride, dropwise add 15 g of 2-methyl-N-(oxirane-2-ylmethyl)propan-2-amine into the tetramethylammonium chloride solution, keep the temperature at 30°C for 2 h, then raise the temperature to 42°C and continue the reaction for 4 h. After the reaction is completed, cool and distill at normal pressure to obtain a secondary amino cationic etherifying agent;

[0035] (5) Add 22 g of N-vinyl pyrrolidone, 14 g of polyformaldehyde, and 0.07 g of acetic acid catalyst into a flask, introduce nitrogen for 35 min to remove oxygen, heat to 90° C., add a secondary amino cationic etherifying agent, heat to 140° C. and react for 9 h. After the reaction is completed, a cationic modified pyrrolidone is obtained;

[0036] (6) Add 8 g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1.8%, stir to dissolve, add 5 g of cationic modified pyrrolidone and 10 g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 15 min to remove oxygen, add 0.08 g of azobisisobutylamidine hydrochloride initiator, heat to 62 °C to react for 3.5 h, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer;

[0037] (7) 22 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 15 parts by weight of chitosan-based grafted modified copolymer, and 5 parts by weight of polyaluminium silicate were added into a reactor, and the mixture was stirred and mixed at 700 rpm for 12 minutes to obtain a cationic etherifying agent composition for sewage treatment. Example 3

[0038] (1) Add 12 g of oleic acid and 15 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 3.5 g of xylene water-carrying agent, heat to 150°C and react for 3.8 h, then heat to 225°C and react for 2.5 h until no water is carried out. After the reaction is completed, cool to 100°C and remove the unreacted xylene water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0039] (2) Add 18.5 g of the imidazoline intermediate and 9 g of dichlorohexane to anhydrous ethanol solvent, stir and mix, then heat to 82° C. and reflux for 4.5 h. After the reaction is completed, remove the solvent by distillation under reduced pressure, add acetone for recrystallization and purification, and obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0040] (3) Stirring and mixing a gemini imidazoline quaternary ammonium salt cationic etherifying agent and a sodium hydroxide aqueous solution with a mass fraction of 28%, spraying the mixture on corn starch, wherein the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.17:2.75, mixing the mixture thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 182 W for 7 min. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain gemini imidazoline quaternary ammonium salt etherified starch;

[0041] (4) Add 9 g of tetramethylammonium chloride and deionized water into a flask, stir at 14°C for 30 min to fully dissolve the tetramethylammonium chloride, dropwise add 11 g of 2-methyl-N-(oxirane-2-ylmethyl)propan-2-amine into the tetramethylammonium chloride solution, keep the temperature at 28°C for 1.5 h, then raise the temperature to 38°C and continue the reaction for 3.2 h. After the reaction is completed, cool and distill at normal pressure to obtain a secondary amino cationic etherifying agent;

[0042] (5) Add 18.5 g of N-vinyl pyrrolidone, 12.5 g of polyformaldehyde, and 0.05 g of acetic acid catalyst into a flask, introduce nitrogen for 28 min to remove oxygen, heat to 86 ° C, add a secondary amino cationic etherifying agent, heat to 130 ° C to react for 7 h, and after the reaction is completed, a cationic modified pyrrolidone is obtained;

[0043] (6) Add 6 g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1.4%, stir to dissolve, add 3.5 g of cationic modified pyrrolidone and 8 g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 12 min to remove oxygen, add 0.05 g of azobisisobutylamidine hydrochloride initiator, heat to 58 °C to react for 2.8 h, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer;

[0044] (7) 18 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 13 parts by weight of chitosan-based grafted modified copolymer, and 3 parts by weight of polyaluminium silicate were added into a reactor and stirred at 550 rpm for 8 min to obtain a cationic etherifying agent composition for wastewater treatment. Example 4

[0045] (1) Add 10 g of oleic acid and 12 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 2 g of xylene water-carrying agent, heat to 145°C for reaction for 3.5 h, then heat to 220°C for reaction for 2 h until no water is carried out, after the reaction is completed, cool to 90°C and remove unreacted xylene water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0046] (2) Add 17 g of the imidazoline intermediate and 7 g of dichlorohexane to anhydrous ethanol solvent, stir and mix, then heat to 78° C. and reflux for 3 h. After the reaction is completed, remove the solvent by distillation under reduced pressure, add acetone for recrystallization and purification, and obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0047] (3) Stirring and mixing a gemini imidazoline quaternary ammonium salt cationic etherifying agent and a sodium hydroxide aqueous solution with a mass fraction of 24%, spraying the mixture on corn starch, wherein the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.14:2.7, mixing the mixture thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 178 W for 4 min. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain gemini imidazoline quaternary ammonium salt etherified starch;

[0048] (4) Add 12 g of tetramethylammonium chloride and deionized water into a flask, stir at 18°C ​​for 40 min to fully dissolve the tetramethylammonium chloride, dropwise add 15 g of 2-methyl-N-(oxirane-2-ylmethyl)propan-2-amine into the tetramethylammonium chloride solution, keep the temperature at 30°C for 2 h, then raise the temperature to 42°C and continue the reaction for 4 h. After the reaction is completed, cool and distill at normal pressure to obtain a secondary amino cationic etherifying agent;

[0049] (5) Add 22 g of N-vinyl pyrrolidone, 14 g of polyformaldehyde, and 0.07 g of acetic acid catalyst into a flask, introduce nitrogen for 35 min to remove oxygen, heat to 90° C., add a secondary amino cationic etherifying agent, heat to 140° C. and react for 9 h. After the reaction is completed, a cationic modified pyrrolidone is obtained;

[0050] (6) Add 6 g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1.4%, stir to dissolve, add 3.5 g of cationic modified pyrrolidone and 8 g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 12 min to remove oxygen, add 0.05 g of azobisisobutylamidine hydrochloride initiator, heat to 58 °C to react for 2.8 h, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer;

[0051] (7) 18 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 13 parts by weight of chitosan-based grafted modified copolymer, and 3 parts by weight of polyaluminium silicate were added into a reactor and stirred at 550 rpm for 8 min to obtain a cationic etherifying agent composition for wastewater treatment. Example 5

[0052] (1) Add 12 g of oleic acid and 15 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 3.5 g of xylene water-carrying agent, heat to 150°C and react for 3.8 h, then heat to 225°C and react for 2.5 h until no water is carried out. After the reaction is completed, cool to 100°C and remove the unreacted xylene water-carrying agent by vacuum distillation to obtain an imidazoline intermediate;

[0053] (2) Add 18.5 g of the imidazoline intermediate and 9 g of dichlorohexane to anhydrous ethanol solvent, stir and mix, then heat to 82° C. and reflux for 4.5 h. After the reaction is completed, remove the solvent by distillation under reduced pressure, add acetone for recrystallization and purification, and obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent;

[0054] (3) Stirring and mixing a gemini imidazoline quaternary ammonium salt cationic etherifying agent and a sodium hydroxide aqueous solution with a mass fraction of 28%, spraying the mixture on corn starch, wherein the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.17:2.75, mixing the mixture thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 182 W for 7 min. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain gemini imidazoline quaternary ammonium salt etherified starch;

[0055] (4) Add 6 g of tetramethylammonium chloride and deionized water into a flask, stir at 10°C for 20 min to fully dissolve the tetramethylammonium chloride, dropwise add 7 g of 2-methyl-N-(oxiran-2-ylmethyl)propan-2-amine into the tetramethylammonium chloride solution, keep the temperature at 25°C for 1 h, then raise the temperature to 35°C and continue the reaction for 2.5 h. After the reaction is completed, cool and distill at normal pressure to obtain a secondary amino cationic etherifying agent;

[0056] (5) Add 15 g of N-vinyl pyrrolidone, 11 g of polyformaldehyde, and 0.04 g of acetic acid catalyst into a flask, introduce nitrogen for 20 min to remove oxygen, heat to 82 °C, add a secondary amino cationic etherifying agent, heat to 120 °C and react for 5 h. After the reaction is completed, a cationic modified pyrrolidone is obtained;

[0057] (6) Add 8 g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1.8%, stir to dissolve, add 5 g of cationic modified pyrrolidone and 10 g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 15 min to remove oxygen, add 0.08 g of azobisisobutylamidine hydrochloride initiator, heat to 62 °C to react for 3.5 h, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer;

[0058] (7) 22 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 15 parts by weight of chitosan-based grafted modified copolymer, and 5 parts by weight of polyaluminium silicate were added into a reactor, and the mixture was stirred and mixed at 700 rpm for 12 minutes to obtain a cationic etherifying agent composition for sewage treatment.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that step (7) does not contain gemini imidazoline quaternary ammonium salt etherified starch.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that step (7) does not contain chitosan-based graft-modified copolymer.

[0063] Pour 1L of urban sewage sample into a beaker, add a predetermined amount of cationic etherifying agent composition for sewage treatment, set the agitator to 200r / min, stir quickly for 2min, adjust to 80r / min, and stir slowly for 15min. After settling for 40min, take the supernatant to measure COD and turbidity. Compare the measurement results with the initial data and calculate the COD and turbidity removal rates. Urban sewage samples were taken from a municipal sewage treatment plant in a certain city (COD was 57.91mg / L, turbidity was 208NTU, and initial pH was 7.5). The dosage of the cationic etherifying agent composition for sewage treatment was 20mg / L. The test results are shown in Table 1.

[0064] Table 1: Flocculation performance test.

[0065] project COD removal rate (%) Turbidity removal rate (%) Example 1 99.6 96.3 Example 2 99.4 96.0 Example 3 98.8 95.8 Example 4 99.7 96.5 Example 5 98.9 97.2 Comparative Example 1 92.8 90.6 Comparative Example 2 91.4 90.0

[0066] It can be seen from Table 1 that the cationic etherifying agent composition in Examples 1-5 of the present invention has a better flocculation effect on sewage than the cationic etherifying agent composition in Comparative Example 1-2.

[0067] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A cationic etherifying agent composition for sewage treatment, characterized in that: The invention comprises the following components by weight: 14-22 parts by weight of gemini imidazoline quaternary ammonium salt etherified starch, 10-15 parts by weight of chitosan-based grafted modified copolymer, and 2-5 parts by weight of polyaluminium silicate; The method for preparing the gemini imidazoline quaternary ammonium salt etherified starch comprises the following steps: (1) Add 10-14 g of oleic acid and 12-18 g of N1-(4-chlorophenyl)ethane-1,2-diamine to a flask, stir and mix, then add 2-5 g of a water-carrying agent, heat to 145-155° C. to react for 3.5-4 h, then heat to 220-230° C. to react for 2-3 h until no water is carried out, and after the reaction is completed, cool to 90-110° C. and remove the unreacted water-carrying agent by vacuum distillation to obtain an imidazoline intermediate; (2) adding 17-20 g of the imidazoline intermediate and 7-11 g of dichlorohexane to anhydrous ethanol solvent, stirring and mixing, and then heating to 78-85° C. for reflux reaction. After the reaction is completed, the solvent is removed by distillation under reduced pressure, and acetone is added for recrystallization and purification to obtain a gemini imidazoline quaternary ammonium salt cationic etherifying agent; (3) Stirring and mixing a cationic etherifying agent of a gemini imidazoline quaternary ammonium salt and a sodium hydroxide aqueous solution with a mass fraction of 24% to 32%, spraying the mixture on corn starch, mixing the mixture thoroughly, placing the mixture in a microwave oven, and irradiating the mixture at a power of 178 to 186 W for 4 to 10 minutes. After the reaction is completed, washing the mixture with anhydrous ethanol, filtering the mixture with suction, and drying the mixture to obtain a gemini imidazoline quaternary ammonium salt etherified starch. The method for preparing the chitosan-based graft-modified copolymer comprises the following steps: S1. Add 6-12g of tetramethylammonium chloride and deionized water to a flask, stir at 10-18 ° C for 20-40min to fully dissolve the tetramethylammonium chloride, add 7-15g of 2-methyl-N-(oxirane-2-ylmethyl)propan-2-amine dropwise to the tetramethylammonium chloride solution, keep the reaction at 25-30 ° C for 1-2h, then raise the temperature to 35-42 ° C and continue the reaction for 2.5-4h. After the reaction is completed, cool and distill at atmospheric pressure to obtain a secondary amino cationic etherifying agent; S2. 15-22 g of N-vinyl pyrrolidone, 11-14 g of paraformaldehyde, and 0.04-0.07 g of acetic acid catalyst were added to a flask, nitrogen was introduced for 20-35 min to remove oxygen, the temperature was raised to 82-90 ° C, a secondary amino cationic etherifying agent was added thereto, the temperature was raised to 120-140 ° C for 5-9 h, and after the reaction, a cationic modified pyrrolidone was obtained; S3. Add 4-8g of chitosan to an aqueous solution of acetic acid with a mass fraction of 1%-1.8%, stir to dissolve, add 2-5g of cationic modified pyrrolidone and 6-10g of acrylamide, adjust the solution pH to 7, introduce nitrogen for 10-15 minutes to remove oxygen, add 0.02-0.08g of initiator, raise the temperature to 55-62°C to react for 2-3.5 hours, and after the reaction is completed, vacuum dry to obtain a chitosan-based grafted modified copolymer.

2. The cationic etherifying agent composition for sewage treatment according to claim 1, characterized in that: The water-carrying agent in step (1) is xylene.

3. The cationic etherifying agent composition for sewage treatment according to claim 1, characterized in that: The reaction time in step (2) is 3-6 hours.

4. The cationic etherifying agent composition for sewage treatment according to claim 1, characterized in that: In the step (3), the molar ratio of the gemini imidazoline quaternary ammonium salt cationic etherifying agent, sodium hydroxide, and starch is 1:1.14-1.2:2.7-2.

8.

5. The cationic etherifying agent composition for sewage treatment according to claim 1, characterized in that: The initiator in S3 is azobisisobutyramidine hydrochloride.

6. A method for preparing a cationic etherifying agent composition for sewage treatment according to any one of claims 1 to 5, characterized in that: The preparation method of the cationic etherifying agent composition for sewage treatment is as follows: Gemini imidazoline quaternary ammonium salt etherified starch, chitosan-based grafted modified copolymer, and polyaluminum silicate are added into a reactor, and stirred and mixed at 400-700 rpm for 5-12 minutes to obtain the cationic etherifying agent composition for sewage treatment.