A composite flocculant containing a cationic etherifying agent and a preparation method thereof

Abstract

The invention relates to the technical field of flocculants, and in particular to a composite flocculant containing a cationic etherifying agent and a preparation method thereof. The composite flocculant comprises the following raw materials in parts by weight: 15-20 parts of carboxymethyl guar gum, 12-15 parts of cationic konjac glucomannan, 1.2-1.5 parts of cationic etherifying agent, 1.8-2.2 parts of magnetic polysilicate metal salt flocculant, and 0.2-0.3 parts of preservative. By compounding the flocculant, the flocculated flocs have magnetism and can be recycled and reused. Furthermore, since a photoresponsive azobenzene structure is grafted into the cationic konjac glucomannan, controllable pollutant aggregation and separation are achieved, ensuring that the composite flocculant can maintain good flocculation performance after multiple recycling and reuse.

Description

Technical Field

[0001] The present invention relates to the technical field of flocculants, in particular to a composite flocculant containing a cationic etherifying agent and a preparation method thereof. Background Art

[0002] Water resource pollution occurs when pollutants discharged from various pollution sources enter the water. These pollutants include soluble substances and insoluble impurities, which interact in the water to form charged colloidal particles. Therefore, they are difficult to separate by simple physical sedimentation. Currently, flocculants are typically added to water samples to alter the stability of the colloidal particles, causing them to destabilize and precipitate, achieving the purpose of separation and purification. For example, patent CN112919602B, "Guar Gum-Inorganic Salt Hybrid Green Flocculant for Enhanced Dehydration of Bottom Mud and Heavy Metal Fixation and Its Preparation Method," uses sulfonated guar gum as a raw material, modifies it, and then compounds it with inorganic aluminum salts or iron salts to achieve a good flocculation effect. However, the flocculant cannot be recovered after flocculation, failing to meet market demand. Summary of the Invention

[0003] The present invention aims to provide a composite flocculant containing a cationic etherifying agent and a preparation method thereof. Carboxymethyl guar gum, cationic konjac glucomannan, a cationic etherifying agent and a magnetic polysilicate metal salt flocculant are compounded to make the flocculated flocs magnetic and recyclable. Furthermore, since a photoresponsive azobenzene structure is grafted onto the cationic konjac glucomannan, controllable pollutant aggregation and separation are achieved, ensuring that the composite flocculant can maintain good flocculation performance after multiple recycling and reuse.

[0004] The object of the present invention can be achieved by the following technical solution: a method for preparing a composite flocculant containing a cationic etherifying agent, comprising the following steps: Step S1: weighing the following raw materials in parts by weight: 15-20 parts of carboxymethyl guar gum, 12-15 parts of cationic konjac glucomannan, 1.2-1.5 parts of a cationic etherifying agent, 1.8-2.2 parts of a magnetic polysilicate metal salt flocculant, and 0.2-0.3 parts of a preservative;

[0005] Step S2: mixing cationic konjac glucomannan, a preservative, and a magnetic polysilicate metal salt flocculant, stirring at 40° C. for 15-20 minutes, then adding carboxymethyl guar gum and a cationic etherifying agent, heating to 50° C., continuing stirring for 1.5-2 hours, and aging for 12 hours to obtain a composite flocculant containing a cationic etherifying agent;

[0006] The carboxymethyl guar gum is produced by Jiangsu Juchuang Bioengineering Co., Ltd., with a specification of 100 mesh and product number 5581;

[0007] The cationic etherifying agent is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride or epoxypropyltrimethylammonium chloride;

[0008] The preservative is Aoke potassium sorbate;

[0009] The cationic konjac glucomannan is prepared by the following steps:

[0010] Step A1: Azobenzene-4-benzoic acid, 3-dimethylaminopropylamine and tetrahydrofuran were mixed, stirred at a rate of 160-180 rpm at room temperature, and N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added, and the reaction was carried out for 20-24 hours. The mixture was distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 1. Intermediate 1, hydrochloric acid solution and ethanol were mixed, stirred at a rate of 160-180 rpm at room temperature, and epichlorohydrin was added. The mixture was stirred for 10-15 minutes, the temperature was raised to 60-65°C, the reaction was carried out for 2-2.5 hours, distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 2.

[0011] The amount ratio of azobenzene-4-benzoic acid, 3-dimethylaminopropylamine, tetrahydrofuran, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is 1.1-1.15g: 0.45-0.48g: 25-30mL: 0.95-0.98g: 0.62-0.65g; the mass fraction of the hydrochloric acid solution is 35%, and the amount ratio of intermediate 1, hydrochloric acid solution, ethanol and epichlorohydrin is 2.4-2.6g: 5-8mL: 35-40mL: 3.8mL-4.1mL;

[0012] During the reaction, under the action of N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole, the carboxyl group in azobenzene-4-benzoic acid reacts with the primary amine group in 3-dimethylaminopropylamine to form an amide structure to prepare intermediate 1. The tertiary amine structure in intermediate 1 then reacts with epichlorohydrin to form a quaternary ammonium salt structure to prepare intermediate 2.

[0013] Step A2: Intermediate 2, phenothiazine, and ethanol were mixed, stirred at a stirring rate of 120-140 rpm and a temperature of 60-65° C., and dimethylaminoethyl acrylate was added. The mixture was reacted for 20-24 hours, and the mixture was distilled under reduced pressure, recrystallized from acetone / ethyl acetate, filtered, washed, and dried to obtain a cationic modifier.

[0014] The ratio of intermediate 2, phenothiazine, ethanol and dimethylaminoethyl acrylate is 2.5-2.6 g: 0.006-0.008 g: 45-50 mL: 0.78-0.79 mL;

[0015] During the reaction, the chlorine in the intermediate 2 reacts with the tertiary amine structure in dimethylaminoethyl acrylate to form a quaternary ammonium salt structure and introduce a double bond to prepare a cationic modifier.

[0016]

[0017] Step A3: Konjac glucomannan and deionized water are mixed and stirred at a stirring rate of 120-140 rpm and a temperature of 40° C. for 10-15 minutes. Then, under nitrogen protection, ammonium cerium nitrate and a cationic modifier are added with stirring and reacted for 4-5 hours. The mixture is precipitated with acetone, filtered, washed, and dried to obtain cationic Konjac glucomannan.

[0018] The dosage ratio of konjac glucomannan, deionized water, cerium ammonium nitrate and cationic modifier is 1.2-1.4 g:120-130 mL:0.042-0.045 g:3.4-3.6 g;

[0019] During the reaction, ammonium cerium nitrate is used as an initiator, konjac glucomannan is used as a base material, and a cationic modifier is used as a monomer. The cationic modifier is grafted onto the konjac glucomannan through a free radical graft copolymerization reaction to prepare cationic konjac glucomannan.

[0020] The konjac glucomannan is from Guchen Biotechnology, and the product number is GC18123.

[0021] The magnetic polysilicate metal salt flocculant is prepared by the following steps:

[0022] Mixing ferroferric oxide magnetic particles, sodium metasilicate nonahydrate, and deionized water, stirring at a rate of 120-140 rpm and a temperature of 40° C., adding sulfuric acid solution and sodium hydroxide solution, adjusting the pH value to 3, stirring for 2-3 hours, aging for 24 hours, and then adding aluminum sulfate solution and sodium tetraborate solution, stirring at a rate of 120-140 rpm and a temperature of 40° C. for 2-3 hours to prepare a magnetic polysilicate metal salt flocculant;

[0023] The mass fraction of the sulfuric acid solution is 30%, the mass fraction of the sodium hydroxide solution is 15%, the molar concentration of the aluminum sulfate solution is 0.3 mol / L, the molar concentration of the sodium tetraborate solution is 0.15 mol / L, and the dosage ratio of the ferroferric oxide magnetic particles, sodium metasilicate nonahydrate, deionized water, aluminum sulfate solution, and sodium tetraborate solution is 1.2-1.4 g: 14-15 g: 300-350 mL: 40-45 mL: 5-8 mL;

[0024] The ferroferric oxide magnetic particles are ferroferric oxide from Zhongke Yannuo, with a specification of 50-300nm;

[0025] During the reaction process, with ferroferric oxide magnetic particles as the core, sodium metasilicate nonahydrate polymerizes and wraps the ferroferric oxide magnetic particle core under acidic conditions, and aluminum sulfate solution and sodium tetraborate solution are used as aluminum and boron sources to introduce aluminum ions and boron ions to modify it and obtain a magnetic polysilicate metal salt flocculant.

[0026] The beneficial effects of the present invention are as follows: the present invention discloses a composite flocculant containing a cationic etherifying agent and a preparation method thereof. By compounding carboxymethyl guar gum, cationic konjac glucomannan, a cationic etherifying agent and a magnetic polysilicate metal salt flocculant, the flocculated flocs are magnetic and can be recovered and reused. Furthermore, since a photoresponsive azobenzene structure is grafted onto the cationic konjac glucomannan, controllable pollutant aggregation and separation are achieved, ensuring that the composite flocculant can maintain good flocculation performance after multiple recycling and reuse.

[0027] Due to the presence of a large number of carboxymethyl structures and quaternary ammonium structures in carboxymethyl guar gum and cationic konjac glucomannan, they can form a complex through electrostatic attraction, thereby enhancing the charge neutralization efficiency. In addition, since the carboxymethyl guar gum has a branched structure and the cationic konjac glucomannan has a linear main chain, the complex forms flocs, further improving the flocculation effect. In addition, due to the presence of a large number of boron ions in the magnetic polysilicate metal salt flocculant, they can combine with the cis-ortho hydroxyl groups in guar gum and konjac glucomannan, thereby being grafted into the flocs, not only exerting an inorganic-organic composite effect, but also making the flocs magnetic and easy to recycle. The cationic konjac glucomannan is grafted with a photoresponsive azobenzene structure, and its azobenzene structure undergoes reversible cis-trans isomerization under ultraviolet and visible light irradiation, thereby changing the charge distribution and molecular configuration of the flocculant, so that the composite flocculant deflocculates during the recovery process, releasing pollutants, and improving the recycling and reuse performance of the flocculant. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the H NMR spectrum of intermediate 1 in Example 3;

[0029] Figure 2 This is the H NMR spectrum of intermediate 2 in Example 3;

[0030] Figure 3 This is the H NMR spectrum of the cationic modifier of Example 3. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] Example 1 A method for preparing a composite flocculant containing a cationic etherifying agent comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 15 parts of carboxymethyl guar gum, 12 parts of cationic konjac glucomannan, 1.2 parts of a cationic etherifying agent, 1.8 parts of a magnetic polysilicate metal salt flocculant, and 0.2 parts of a preservative;

[0033] Step S2: mixing cationic konjac glucomannan, a preservative, and a magnetic polysilicate metal salt flocculant, stirring at 40° C. for 15 minutes, then adding carboxymethyl guar gum and a cationic etherifying agent, heating to 50° C., continuing stirring for 1.5 hours, and aging for 12 hours to obtain a composite flocculant containing a cationic etherifying agent;

[0034] The carboxymethyl guar gum is produced by Jiangsu Juchuang Bioengineering Co., Ltd., with a specification of 100 mesh and product number 5581;

[0035] The cationic etherifying agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride;

[0036] The preservative is Aoke potassium sorbate;

[0037] The cationic konjac glucomannan is prepared by the following steps:

[0038] Step A1: Azobenzene-4-benzoic acid, 3-dimethylaminopropylamine and tetrahydrofuran were mixed, stirred at a rate of 160 rpm at room temperature, and N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added, and the mixture was reacted for 20 hours. The mixture was distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 1. Intermediate 1, hydrochloric acid solution and ethanol were mixed, stirred at a rate of 160 rpm at room temperature, and epichlorohydrin was added. The mixture was stirred for 10 minutes, the temperature was raised to 60°C, the mixture was reacted for 2 hours, distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 2.

[0039] The amount ratio of azobenzene-4-benzoic acid, 3-dimethylaminopropylamine, tetrahydrofuran, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is 1.1g:0.45g:25mL:0.95g:0.62g; the mass fraction of hydrochloric acid solution is 35%, and the amount ratio of intermediate 1, hydrochloric acid solution, ethanol and epichlorohydrin is 2.4g:5mL:35mL:3.8mL;

[0040] Step A2: Intermediate 2, phenothiazine, and ethanol were mixed, stirred at a stirring rate of 120 rpm and a temperature of 60°C, and dimethylaminoethyl acrylate was added. The mixture was reacted for 20 hours, distilled under reduced pressure, recrystallized from acetone / ethyl acetate, filtered, washed, and dried to obtain a cationic modifier.

[0041] The amount ratio of intermediate 2, phenothiazine, ethanol and dimethylaminoethyl acrylate is 2.5g:0.006g:45mL:0.78mL;

[0042] Step A3: Konjac glucomannan and deionized water were mixed and stirred at a stirring rate of 120 rpm and a temperature of 40° C. for 10 minutes. Then, under nitrogen protection, ammonium cerium nitrate and a cationic modifier were added with stirring and reacted for 4 hours. The mixture was precipitated with acetone, filtered, washed, and dried to obtain cationic konjac glucomannan.

[0043] The ratio of konjac glucomannan, deionized water, cerium ammonium nitrate and cationic modifier is 1.2 g:120 mL:0.042 g:3.4 g;

[0044] The konjac glucomannan is from Guchen Biotechnology, with the product number GC18123;

[0045] The magnetic polysilicate metal salt flocculant is prepared by the following steps:

[0046] The ferroferric oxide magnetic particles, sodium metasilicate nonahydrate and deionized water were mixed, stirred at a stirring rate of 120 rpm and a temperature of 40°C, and sulfuric acid solution and sodium hydroxide solution were added, the pH value was adjusted to 3, stirred for 2 hours, and aged for 24 hours. Then, aluminum sulfate solution and sodium tetraborate solution were added, and stirred at a stirring rate of 120 rpm and a temperature of 40°C for 3 hours to prepare a magnetic polysilicate metal salt flocculant.

[0047] The mass fraction of sulfuric acid solution is 30%, the mass fraction of sodium hydroxide solution is 15%, the molar concentration of aluminum sulfate solution is 0.3 mol / L, the molar concentration of sodium tetraborate solution is 0.15 mol / L, and the amount ratio of ferroferric oxide magnetic particles, sodium metasilicate nonahydrate, deionized water, aluminum sulfate solution and sodium tetraborate solution is 1.4 g:14 g:350 mL:40 mL:8 mL;

[0048] The ferroferric oxide magnetic particles are ferroferric oxide produced by Zhongke Yannuo, with a specification of 50-300nm.

[0049] Example 2 A method for preparing a composite flocculant containing a cationic etherifying agent comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 20 parts of carboxymethyl guar gum, 12 parts of cationic konjac glucomannan, 1.5 parts of a cationic etherifying agent, 1.8 parts of a magnetic polysilicate metal salt flocculant, and 0.3 parts of a preservative;

[0050] Step S2: mixing cationic konjac glucomannan, a preservative, and a magnetic polysilicate metal salt flocculant, stirring at 40° C. for 20 minutes, then adding carboxymethyl guar gum and a cationic etherifying agent, heating to 50° C., continuing stirring for 1.5 hours, and aging for 12 hours to obtain a composite flocculant containing a cationic etherifying agent;

[0051] The carboxymethyl guar gum is produced by Jiangsu Juchuang Bioengineering Co., Ltd., with a specification of 100 mesh and product number 5581;

[0052] The cationic etherifying agent is epoxypropyltrimethylammonium chloride;

[0053] The preservative is Aoke potassium sorbate;

[0054] The cationic konjac glucomannan is prepared by the following steps:

[0055] Step A1: Azobenzene-4-benzoic acid, 3-dimethylaminopropylamine and tetrahydrofuran were mixed, stirred at a rate of 180 rpm at room temperature, and N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added, and the mixture was reacted for 20 hours. The mixture was distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 1. Intermediate 1, hydrochloric acid solution and ethanol were mixed, stirred at a rate of 160 rpm at room temperature, and epichlorohydrin was added. The mixture was stirred for 15 minutes, the temperature was raised to 60°C, the mixture was reacted for 2.5 hours, distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 2.

[0056] The amount ratio of azobenzene-4-benzoic acid, 3-dimethylaminopropylamine, tetrahydrofuran, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is 1.1g:0.48g:25mL:0.95g:0.65g; the mass fraction of hydrochloric acid solution is 35%, and the amount ratio of intermediate 1, hydrochloric acid solution, ethanol and epichlorohydrin is 2.6g:5mL:35mL:4.1mL;

[0057] Step A2: Intermediate 2, phenothiazine, and ethanol were mixed, stirred at a stirring rate of 120 rpm and a temperature of 60°C, and dimethylaminoethyl acrylate was added. The mixture was reacted for 24 hours, distilled under reduced pressure, recrystallized from acetone / ethyl acetate, filtered, washed, and dried to obtain a cationic modifier.

[0058] The ratio of intermediate 2, phenothiazine, ethanol and dimethylaminoethyl acrylate is 2.5 g:0.008 g:45 mL:0.78 mL;

[0059] Step A3: Konjac glucomannan and deionized water were mixed and stirred at a stirring rate of 140 rpm and a temperature of 40° C. for 10 minutes. Then, under nitrogen protection, ammonium cerium nitrate and a cationic modifier were added with stirring and reacted for 4 hours. The mixture was precipitated with acetone, filtered, washed, and dried to obtain cationic konjac glucomannan.

[0060] The ratio of konjac glucomannan, deionized water, cerium ammonium nitrate and cationic modifier is 1.4 g:120 mL:0.042 g:3.6 g;

[0061] The konjac glucomannan is from Guchen Biotechnology, with the product number GC18123;

[0062] The magnetic polysilicate metal salt flocculant is prepared by the following steps:

[0063] The ferroferric oxide magnetic particles, sodium metasilicate nonahydrate and deionized water were mixed, stirred at a stirring rate of 120 rpm and a temperature of 40°C, and sulfuric acid solution and sodium hydroxide solution were added, the pH value was adjusted to 3, stirred for 3 hours, and aged for 24 hours. Then, aluminum sulfate solution and sodium tetraborate solution were added, and stirred at a stirring rate of 120 rpm and a temperature of 40°C for 3 hours to prepare a magnetic polysilicate metal salt flocculant.

[0064] The mass fraction of sulfuric acid solution is 30%, the mass fraction of sodium hydroxide solution is 15%, the molar concentration of aluminum sulfate solution is 0.3 mol / L, the molar concentration of sodium tetraborate solution is 0.15 mol / L, and the amount ratio of ferroferric oxide magnetic particles, sodium metasilicate nonahydrate, deionized water, aluminum sulfate solution and sodium tetraborate solution is 1.4 g:14 g:350 mL:40 mL:8 mL;

[0065] The ferroferric oxide magnetic particles are ferroferric oxide produced by Zhongke Yannuo, with a specification of 50-300nm.

[0066] Example 3 A method for preparing a composite flocculant containing a cationic etherifying agent comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 20 parts of carboxymethyl guar gum, 15 parts of cationic konjac glucomannan, 1.5 parts of a cationic etherifying agent, 2.2 parts of a magnetic polysilicate metal salt flocculant, and 0.3 parts of a preservative;

[0067] Step S2: mixing cationic konjac glucomannan, a preservative, and a magnetic polysilicate metal salt flocculant, stirring at 40° C. for 20 minutes, then adding carboxymethyl guar gum and a cationic etherifying agent, heating to 50° C., continuing stirring for 2 hours, and aging for 12 hours to obtain a composite flocculant containing a cationic etherifying agent;

[0068] The carboxymethyl guar gum is produced by Jiangsu Juchuang Bioengineering Co., Ltd., with a specification of 100 mesh and product number 5581;

[0069] The cationic etherifying agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride;

[0070] The preservative is Aoke potassium sorbate;

[0071] The cationic konjac glucomannan is prepared by the following steps:

[0072] Step A1: Azobenzene-4-benzoic acid, 3-dimethylaminopropylamine and tetrahydrofuran were mixed, stirred at a rate of 180 rpm at room temperature, and N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added, and the mixture was reacted for 24 hours. The mixture was distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 1. Intermediate 1, hydrochloric acid solution and ethanol were mixed, stirred at a rate of 180 rpm at room temperature, and epichlorohydrin was added. The mixture was stirred for 15 minutes, the temperature was raised to 65°C, the mixture was reacted for 2.5 hours, distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 2.

[0073] The amount ratio of azobenzene-4-benzoic acid, 3-dimethylaminopropylamine, tetrahydrofuran, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is 1.15g:0.48g:30mL:0.98g:0.65g; the mass fraction of the hydrochloric acid solution is 35%, and the amount ratio of intermediate 1, hydrochloric acid solution, ethanol and epichlorohydrin is 2.6g:8mL:40mL:4.1mL;

[0074] Figure 1 This is the nuclear magnetic hydrogen spectrum of intermediate 1 in Example 3, Figure 1 It can be seen that an obvious [-NH-] characteristic peak appears at δ = 8.4-8.5, indicating that azobenzene-4-benzoic acid and 3-dimethylaminopropylamine react successfully;

[0075] Figure 2 This is the nuclear magnetic hydrogen spectrum of intermediate 2 in Example 3, Figure 2 It can be seen that an obvious [-CH3-] characteristic peak appears at δ = 3.2-3.3, and an obvious [-OH] characteristic peak appears at δ = 6.1-6.2, indicating that intermediate 1 successfully reacts with epichlorohydrin;

[0076] Step A2: Intermediate 2, phenothiazine, and ethanol were mixed, stirred at a stirring rate of 140 rpm and a temperature of 65°C, and dimethylaminoethyl acrylate was added. The mixture was reacted for 24 hours, distilled under reduced pressure, recrystallized from acetone / ethyl acetate, filtered, washed, and dried to obtain a cationic modifier.

[0077] The ratio of intermediate 2, phenothiazine, ethanol and dimethylaminoethyl acrylate is 2.6 g:0.008 g:50 mL:0.79 mL;

[0078] Figure 3 This is the nuclear magnetic hydrogen spectrum of the cationic modifier of Example 3, Figure 3 It can be seen that there is an obvious carbon-carbon unsaturated double bond characteristic peak at δ = 5.8-9.5, indicating that intermediate 2 successfully reacts with dimethylaminoethyl acrylate to introduce an unsaturated double bond;

[0079] Step A3: Konjac glucomannan and deionized water were mixed and stirred at a stirring rate of 140 rpm and a temperature of 40° C. for 15 minutes. Then, under nitrogen protection, cerium ammonium nitrate and a cationic modifier were added with stirring and reacted for 5 hours. The mixture was precipitated with acetone, filtered, washed, and dried to obtain cationic konjac glucomannan.

[0080] The ratio of konjac glucomannan, deionized water, cerium ammonium nitrate and cationic modifier is 1.4 g:130 mL:0.045 g:3.6 g;

[0081] The konjac glucomannan is from Guchen Biotechnology, with the product number GC18123;

[0082] The magnetic polysilicate metal salt flocculant is prepared by the following steps:

[0083] The ferroferric oxide magnetic particles, sodium metasilicate nonahydrate and deionized water were mixed, stirred at a stirring rate of 140 rpm and a temperature of 40°C, and sulfuric acid solution and sodium hydroxide solution were added, the pH value was adjusted to 3, stirred for 3 hours, and aged for 24 hours. Then, aluminum sulfate solution and sodium tetraborate solution were added, and stirred at a stirring rate of 140 rpm and a temperature of 40°C for 3 hours to prepare a magnetic polysilicate metal salt flocculant.

[0084] The mass fraction of sulfuric acid solution is 30%, the mass fraction of sodium hydroxide solution is 15%, the molar concentration of aluminum sulfate solution is 0.3 mol / L, the molar concentration of sodium tetraborate solution is 0.15 mol / L, and the amount ratio of ferroferric oxide magnetic particles, sodium metasilicate nonahydrate, deionized water, aluminum sulfate solution and sodium tetraborate solution is 1.4 g:15 g:350 mL:45 mL:8 mL;

[0085] The ferroferric oxide magnetic particles are ferroferric oxide produced by Zhongke Yannuo, with a specification of 50-300nm.

[0086] Comparative Example 1 Compared with Example 3, this comparative example removes the aluminum sulfate solution and the sodium tetraborate solution in the preparation process of the magnetic polysilicate metal salt flocculant in Example 3, and the other steps are the same.

[0087] Comparative Example 2 This comparative example is compared with Example 3, except that the cationic konjac glucomannan in the preparation process of the composite flocculant in Example 3 is replaced by konjac glucomannan, and the other steps are the same.

[0088] The composite flocculants prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were taken, 0.1 g of sodium humate, 0.5 g of kaolin and 10 L of deionized water were mixed, and the pH value was adjusted to 8 to prepare a water sample. The turbidity and chromaticity of the water sample were tested and recorded using a multi-parameter water quality meter. The composite flocculant was added to the water sample at an amount of 0.6 g / L. The mixture was stirred at a stirring rate of 180 rpm, a temperature of 30°C and visible light irradiation for 5 min and settled for 10 min. The turbidity and chromaticity of the water sample were measured. The chromaticity was tested, and the turbidity removal rate and chromaticity removal rate were calculated. Turbidity removal rate = (water sample turbidity - water sample turbidity after flocculation) / water sample turbidity * 100%, and chromaticity removal rate = (water sample chromaticity - water sample chromaticity after flocculation) / water sample chromaticity * 100% to evaluate the flocculation performance of the composite flocculant. After the flocculation experiment was completed, the composite flocculant was recovered by magnets for reuse and irradiated with ultraviolet light. The experiment was repeated 10 times, and then the turbidity and chromaticity were tested, and the turbidity removal rate and chromaticity removal rate were calculated. The test results are shown in the following table:

[0089]

[0090] As can be seen from the test results in the table shown, when Example 1, Example 2 and Example 3 are compared with Comparative Example 1 and Comparative Example 2, Comparative Example 1 removes the aluminum sulfate solution and the sodium tetraborate solution in the preparation process of the magnetic polysilicate metal salt flocculant in Example 3. Due to the lack of aluminum ion and boron ion doping, its flocculation performance decreases. Comparative Example 2 replaces the cationic konjac glucomannan in the preparation process of the composite flocculant in Example 3 with konjac glucomannan. Due to the lack of the introduction of azobenzene structure and quaternary ammonium structure, its flocculation performance and recycling performance decrease.

[0091] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0092] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the concept of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite flocculant containing a cationic etherifying agent, characterized in that: The method comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 15-20 parts of carboxymethyl guar gum, 12-15 parts of cationic konjac glucomannan, 1.2-1.5 parts of a cationic etherifying agent, 1.8-2.2 parts of a magnetic polysilicate metal salt flocculant, and 0.2-0.3 parts of a preservative; Step S2: mixing cationic konjac glucomannan, a preservative, and a magnetic polysilicate metal salt flocculant, stirring at 40° C. for 15-20 minutes, then adding carboxymethyl guar gum and a cationic etherifying agent, heating to 50° C., continuing stirring for 1.5-2 hours, and aging for 12 hours to obtain a composite flocculant containing a cationic etherifying agent; The cationic konjac glucomannan is prepared by the following steps: Step A1: Azobenzene-4-benzoic acid, 3-dimethylaminopropylamine and tetrahydrofuran were mixed, stirred at a rate of 160-180 rpm at room temperature, and N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole were added, and the reaction was carried out for 20-24 hours. The mixture was distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 1. Intermediate 1, hydrochloric acid solution and ethanol were mixed, stirred at a rate of 160-180 rpm at room temperature, and epichlorohydrin was added. The mixture was stirred for 10-15 minutes, the temperature was raised to 60-65°C, the reaction was carried out for 2-2.5 hours, distilled under reduced pressure, recrystallized from acetone, filtered, washed, and dried to obtain Intermediate 2. Step A2: Intermediate 2, phenothiazine, and ethanol were mixed, stirred at a stirring rate of 120-140 rpm and a temperature of 60-65° C., and dimethylaminoethyl acrylate was added. The mixture was reacted for 20-24 hours, and the mixture was distilled under reduced pressure, recrystallized from acetone / ethyl acetate, filtered, washed, and dried to obtain a cationic modifier. Step A3: Konjac glucomannan and deionized water are mixed and stirred at a stirring rate of 120-140 rpm and a temperature of 40° C. for 10-15 minutes. Then, under nitrogen protection, ammonium cerium nitrate and a cationic modifier are added with stirring and reacted for 4-5 hours. The mixture is precipitated with acetone, filtered, washed, and dried to obtain cationic Konjac glucomannan. The magnetic polysilicate metal salt flocculant is prepared by the following steps: Mix ferroferric oxide magnetic particles, sodium metasilicate nonahydrate and deionized water, stir at a stirring rate of 120-140 rpm and a temperature of 40°C, add sulfuric acid solution and sodium hydroxide solution, adjust the pH value to 3, stir for 2-3 hours, mature for 24 hours, then add aluminum sulfate solution and sodium tetraborate solution, stir at a stirring rate of 120-140 rpm and a temperature of 40°C for 2-3 hours to prepare a magnetic polysilicate metal salt flocculant.

2. The method for preparing a composite flocculant containing a cationic etherifying agent according to claim 1, characterized in that: In step A1, the ratio of azobenzene-4-benzoic acid, 3-dimethylaminopropylamine, tetrahydrofuran, N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is 1.1-1.15 g: 0.45-0.48 g: 25-30 mL: 0.95-0.98 g: 0.62-0.65 g; The mass fraction of the hydrochloric acid solution is 35%, and the usage ratio of the intermediate 1, the hydrochloric acid solution, ethanol and epichlorohydrin is 2.4-2.6 g: 5-8 mL: 35-40 mL: 3.8-4.1 mL.

3. The method for preparing a composite flocculant containing a cationic etherifying agent according to claim 1, characterized in that: In step A2, the ratio of intermediate 2, phenothiazine, ethanol and dimethylaminoethyl acrylate is 2.5-2.6 g: 0.006-0.008 g: 45-50 mL: 0.78-0.79 mL.

4. The method for preparing a composite flocculant containing a cationic etherifying agent according to claim 1, characterized in that: In step A3, the ratio of konjac glucomannan, deionized water, ceric ammonium nitrate and cationic modifier is 1.2-1.4 g: 120-130 mL: 0.042-0.045 g: 3.4-3.6 g.

5. The method for preparing a composite flocculant containing a cationic etherifying agent according to claim 1, characterized in that: In the preparation process of the magnetic polysilicate metal salt flocculant, the mass fraction of the sulfuric acid solution is 30%, the mass fraction of the sodium hydroxide solution is 15%, the molar concentration of the aluminum sulfate solution is 0.3 mol / L, the molar concentration of the sodium tetraborate solution is 0.15 mol / L, and the dosage ratio of the ferrosilicate magnetic particles, sodium metasilicate nonahydrate, deionized water, the aluminum sulfate solution and the sodium tetraborate solution is 1.2-1.4 g: 14-15 g: 300-350 mL: 40-45 mL: 5-8 mL.

6. A composite flocculant containing a cationic etherifying agent, characterized in that: Prepared according to any one of claims 1 to 5.

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