An organic-inorganic polymer composite flocculant and its preparation method

Abstract

This case involves an organic-inorganic polymer composite flocculant and its preparation method. First, diatomite is etched with acid and alkali; then it is mixed with magnetic powder and hyperbranched polymerization is carried out on its surface using triethylenetetramine as the starting material; after modifying polyaluminum chloride with KH570, polymerization is carried out to prepare polyaluminum chloride-methylacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride; it is dispersed with hyperbranched modified diatomite in deionized water, heated to 60 °C and stirred for 24 h, filtered and dried to obtain. Based on polyaluminum chloride, the present invention has prepared a new type of organic-inorganic hybrid composite polymer flocculant. Loading magnetic powder with diatomite as the carrier endows the flocculant with magnetism, making the recovery more convenient and rapid; the hyperbranched polymer and the polymer chain with cationic groups adsorb and capture pollutants in the water body, with high removal rates of COD and turbidity, and can also inhibit the release of aluminum ions, having a very high purification effect and high safety without secondary pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and specifically to an organic-inorganic polymer composite flocculant and a preparation method thereof. Background Art

[0002] Water treatment refers to physical or chemical measures taken to make water quality meet certain usage standards. Water treatment is of great significance for the development of industrial production, improvement of product quality, protection of the human environment, and maintenance of ecological balance. The agents for water treatment include: adsorbents, corrosion inhibitors, bactericides, flocculants, etc. Among them, the most commonly used water treatment agent is the flocculant, including inorganic or organic substances such as aluminum sulfate, ferric chloride, aluminum chloride, polyaluminum chloride, polyaluminum ferric chloride, activated carbon, polyacrylamide, etc. These products have a high degree of industrialization and low production costs, so they are most widely used. However, there are also some defects. For example, the treatment efficiency of activated carbon is low, and the residues of aluminum chloride, polyacrylamide, etc. in water have an impact on human health. And currently, the components of the sewage sources discharged from industrial production are more complex and difficult to treat, and conventional water treatment agents are difficult to achieve the expected effects. Therefore, it is necessary to develop new water treatment agents. In recent years, researchers have developed a series of inorganic and organic flocculants with improved performance for different water qualities, which has promoted the development of flocculants. However, single-component inorganic flocculants or organic flocculants still have problems such as large dosage and easy secondary pollution. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention proposes an organic-inorganic polymer composite flocculant prepared by combining an organic polymer and polyaluminum chloride, which combines the advantages of inorganic flocculants and organic flocculants, has good flocculation effect and excellent comprehensive performance.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A preparation method of an organic-inorganic polymer composite flocculant, comprising the following steps:

[0006] S1. Acid-base etching of diatomite;

[0007] S2. Crushing the etched diatomite and mixing it with magnetic powder, adding a methanol solvent and stirring evenly, adding triethylenetetramine thereto, stirring evenly under an ice-water bath and nitrogen protection, dropwise adding methyl acrylate, heating to 35°C and reacting overnight, and removing the solvent by reduced pressure distillation; adding methanol again and stirring evenly, dropping triethylenetetramine, reacting overnight at room temperature, and removing the solvent by reduced pressure distillation to obtain hyperbranched modified diatomite;

[0008] S3. Modify polyaluminum chloride with KH570. The modified polyaluminum chloride is polymerized with methacryloyloxyethyl trimethyl ammonium chloride and maleic anhydride under the initiation of ammonium persulfate to obtain polyaluminum chloride - methacryloyloxyethyl trimethyl ammonium chloride - polymaleic anhydride;

[0009] S4. Disperse polyaluminum chloride - methacryloyloxyethyl trimethyl ammonium chloride - polymaleic anhydride and hyperbranched modified diatomite in deionized water, heat to 60 °C and stir for 24 h, filter, wash thoroughly with water and then dry to obtain the product.

[0010] Furthermore, the specific process of step S1 is as follows:

[0011] Weigh a certain amount of diatomite and soak it in sodium hydroxide solution, keep it at a constant temperature of 40 °C for 2 h; after that, filter, wash with water until neutral, dry and then calcine at 350 - 400 °C for 2 - 3 h to obtain a powder; soak the powder in 10% hydrochloric acid solution again, let it stand at room temperature for 1 h, after that, filter, wash with water until neutral, dry and then calcine at 350 - 400 °C for 2 - 3 h.

[0012] Furthermore, in step S2, the mass ratio of diatomite to magnetic powder is 1:0.2 - 0.6, and the mass ratio of triethylenetetramine to diatomite is 1 - 3:1.

[0013] Furthermore, in step S3, the modification of polyaluminum chloride is as follows:

[0014] Add KH570 and absolute ethanol into a reaction flask, adjust the pH to 3 - 4, and stir for 1 - 2 h; ultrasonically disperse polyaluminum chloride in absolute ethanol and then add it into the reaction flask, heat under reflux in a water bath for 2 h, continue to stir overnight at room temperature, centrifuge and separate, dry and reserve; among them, the mass ratio of KH570 to polyaluminum chloride is 1:2.

[0015] Furthermore, in step S3, the molar ratio of methacryloyloxyethyl trimethyl ammonium chloride to maleic anhydride is 1 - 2:3 - 4, and the ratio of the modified polyaluminum chloride, ammonium persulfate to the sum of the masses of methacryloyloxyethyl trimethyl ammonium chloride and maleic anhydride is 30 - 50:0.5:100.

[0016] Furthermore, the mass ratio of polyaluminum chloride - methacryloyloxyethyl trimethyl ammonium chloride - polymaleic anhydride to hyperbranched modified diatomite is 1:0.6 - 1.

[0017] The technical solution provided by this application enables the final flocculant to be recovered by magnetic separation through the addition of magnetic powder. The recovered flocculant can be recycled, saving resources. After acid-base etching, the pore size of diatomite increases. After adding magnetic powder, hyperbranched polymerization is carried out to coat polymer chains on the surface of diatomite, forming a spatial network structure, which enables the magnetic powder to be tightly adsorbed on the surface of diatomite, not easy to fall off, with good magnetic stability and high recovery rate. Hyperbranched polymers contain abundant amino groups, providing abundant active sites. The polyaluminum chloride modified by KH570 has unsaturated double bonds on its surface, which can undergo free radical polymerization. Under the initiation of ammonium persulfate, it polymerizes with maleic anhydride and cationic monomer methacryloyloxyethyl trimethyl ammonium chloride to form a random copolymer of maleic anhydride and methacryloyloxyethyl trimethyl ammonium chloride. The maleic anhydride unit reacts with the amino group on the surface of hyperbranched modified diatomite to open the ring, connecting the hyperbranched modified diatomite with polyaluminum chloride-methacryloyloxyethyl trimethyl ammonium chloride-poly maleic anhydride through covalent bonds, with high stability. The prepared flocculant contains abundant active groups such as quaternary ammonium salts, amino groups, carboxyl groups, and amide groups, which form adsorption bridging effects with organic substances. At the same time, through coordination effects, the release of aluminum ions from polyaluminum chloride is overcome, reducing secondary pollution to water bodies. Structurally, it is similar to a core composed of polyaluminum chloride and diatomite, with a shell formed by a high molecular organic polymer, forming an organic-inorganic hybrid flocculant, achieving the synergistic effects of electro-neutralization of inorganic components and adsorption bridging of organic components, greatly improving the flocculation and sedimentation effects.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on polyaluminum chloride, the present invention has prepared a new type of organic-inorganic hybrid composite polymer flocculant. Loading magnetic powder on diatomite as a carrier endows the flocculant with magnetism, making the recovery more convenient and rapid. Hyperbranched polymers and polymer chains with cationic groups capture pollutants in water bodies through adsorption, with high removal rates of COD and turbidity, and can also inhibit the release of aluminum ions, having a high purification effect and high safety without secondary pollution. Specific Embodiments

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Embodiment: A preparation method of an organic-inorganic polymer composite flocculant includes the following steps:

[0022] S1. Weigh 10 g of diatomaceous earth and soak it in sodium hydroxide solution, keep it at a constant temperature of 40 °C for 2 h. After that, filter it, wash it with water until it is neutral, dry it, and then calcine it at 350 - 400 °C for 2 - 3 h to obtain a powder. Soak the powder in 10% hydrochloric acid solution again, let it stand at room temperature for 1 h. After that, filter it, wash it with water until it is neutral, dry it, and then calcine it at 350 - 400 °C for 2 - 3 h.

[0023] S2. Crush the etched diatomaceous earth and mix it with magnetic powder, add methanol solvent and stir evenly. Add triethylenetetramine to it, stir evenly under ice - water bath and nitrogen protection, dropwise add methyl acrylate, heat up to 35 °C and react overnight, then distill off the solvent under reduced pressure. Re - add methanol and stir evenly, dropwise add triethylenetetramine, react overnight at room temperature, and distill off the solvent under reduced pressure to obtain hyperbranched modified diatomaceous earth. The mass ratio of diatomaceous earth to magnetic powder is 1:0.2 - 0.6, and the mass ratio of triethylenetetramine to diatomaceous earth is 1 - 3:1.

[0024] S3. Use KH570 as a modifier to modify polyaluminum chloride. First, add KH570 and absolute ethanol to the reaction flask, adjust the pH to 3 - 4, and stir for 1 - 2 h. After ultrasonic dispersing polyaluminum chloride in absolute ethanol, add it to the reaction flask, heat it under water bath and reflux for 2 h, continue to stir overnight at room temperature, then centrifuge and separate, and dry it for standby. Among them, the mass ratio of KH570 to polyaluminum chloride is 1:2.

[0025] The modified polyaluminum chloride is polymerized with methacryloyloxyethyl trimethyl ammonium chloride and maleic anhydride under the initiation of ammonium persulfate to obtain polyaluminum chloride - methacryloyloxyethyl trimethyl ammonium chloride - polymaleic anhydride. The molar ratio of methacryloyloxyethyl trimethyl ammonium chloride to maleic anhydride is 1 - 2:3 - 4, and the ratio of the modified polyaluminum chloride, ammonium persulfate to the sum of the masses of methacryloyloxyethyl trimethyl ammonium chloride and maleic anhydride is 30 - 50:0.5:100.

[0026] S4. Disperse polyaluminum chloride - methacryloyloxyethyl trimethyl ammonium chloride - polymaleic anhydride and hyperbranched modified diatomaceous earth in deionized water according to a mass ratio of 1:0.6 - 1, heat up to 60 °C and stir for 24 h, filter, wash thoroughly with water and then dry to obtain the product.

[0027] Example 1:

[0028] S1. Take 2 g of acid - base etched diatomaceous earth and mix it evenly with 0.5 g of magnetic powder, add 20 g of methanol solvent and stir evenly. Add 3 g of triethylenetetramine to it, stir evenly under ice - water bath and nitrogen protection, dropwise add 25 g of methyl acrylate, heat up to 35 °C and react overnight, then distill off the solvent under reduced pressure. Re - add 30 g of methanol and stir evenly, dropwise add 35 g of triethylenetetramine, react overnight at room temperature, and distill off the solvent under reduced pressure to obtain hyperbranched modified diatomaceous earth;

[0029] S2. Disperse the polyaluminum chloride modified by 3 g of KH570 in DMF solvent, add 3.5 g of methacryloyloxyethyltrimethylammonium chloride, 6.5 g of maleic anhydride and 0.05 g of ammonium persulfate. Under nitrogen protection, heat up to 70 °C and carry out the polymerization reaction overnight. Cool to room temperature, precipitate with ethanol, and dry the precipitate after sufficient washing to obtain polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride.

[0030] S3. Disperse the polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride and the hyperbranched modified diatomite in deionized water according to a mass ratio of 1:0.6, heat up to 60 °C and stir for 24 h, filter, wash thoroughly with water and then dry to obtain Flocculant 1.

[0031] Example 2:

[0032] S1. Take 2 g of acid-base etched diatomite and mix it evenly with 0.7 g of magnetic powder, add 20 g of methanol solvent and stir evenly. Add 3 g of triethylenetetramine thereto, stir evenly under ice-water bath and nitrogen protection, dropwise add 25 g of methyl acrylate, heat up to 35 °C and react overnight, and remove the solvent by reduced pressure distillation; add 30 g of methanol again and stir evenly, dropwise add 35 g of triethylenetetramine, react overnight at room temperature, and remove the solvent by reduced pressure distillation to obtain hyperbranched modified diatomite;

[0033] S2. Disperse the polyaluminum chloride modified by 4 g of KH570 in DMF solvent, add 3.5 g of methacryloyloxyethyltrimethylammonium chloride, 6.5 g of maleic anhydride and 0.05 g of ammonium persulfate. Under nitrogen protection, heat up to 70 °C and carry out the polymerization reaction overnight. Cool to room temperature, precipitate with ethanol, and dry the precipitate after sufficient washing to obtain polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride.

[0034] S3. Disperse the polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride and the hyperbranched modified diatomite in deionized water according to a mass ratio of 1:0.7, heat up to 60 °C and stir for 24 h, filter, wash thoroughly with water and then dry to obtain Flocculant 2.

[0035] Example 3:

[0036] S1. Take 2 g of acid-base etched diatomite and mix it evenly with 0.8 g of magnetic powder, add 20 g of methanol solvent and stir evenly. Add 3 g of triethylenetetramine thereto, stir evenly under ice-water bath and nitrogen protection, dropwise add 25 g of methyl acrylate, heat up to 35 °C and react overnight, and remove the solvent by reduced pressure distillation; add 30 g of methanol again and stir evenly, dropwise add 35 g of triethylenetetramine, react overnight at room temperature, and remove the solvent by reduced pressure distillation to obtain hyperbranched modified diatomite;

[0037] S2. Disperse the polyaluminum chloride modified by 5 g of KH570 in DMF solvent, add 4.8 g of methacryloyloxyethyl trimethyl ammonium chloride, 4.2 g of maleic anhydride and 0.05 g of ammonium persulfate. Under nitrogen protection, heat up to 70 °C for overnight polymerization reaction. Cool to room temperature, precipitate with ethanol, and dry the precipitate after sufficient washing to obtain polyaluminum chloride-methacryloyloxyethyl trimethyl ammonium chloride-poly maleic anhydride.

[0038] S3. Disperse polyaluminum chloride-methacryloyloxyethyl trimethyl ammonium chloride-poly maleic anhydride and hyperbranched modified diatomite in deionized water at a mass ratio of 1:0.8, heat up to 60 °C and stir for 24 h, filter, wash thoroughly with water and then dry to obtain Flocculant 3.

[0039] Comparative Example 1:

[0040] The polyaluminum chloride-methacryloyloxyethyl trimethyl ammonium chloride-poly maleic anhydride prepared in step S2 of Example 1 is used as Flocculant 4.

[0041] Comparative Example 2:

[0042] Take 2 g of acid-base etched diatomite and mix it evenly with 0.5 g of magnetic powder. Disperse it together with 3 g of polyaluminum chloride modified by KH570 in DMF solvent, add 3.5 g of methacryloyloxyethyl trimethyl ammonium chloride, 6.5 g of maleic anhydride and 0.05 g of ammonium persulfate. Under nitrogen protection, heat up to 70 °C for overnight polymerization reaction. Cool to room temperature, precipitate with ethanol, and dry the precipitate after sufficient washing. The product is denoted as Flocculant 5.

[0043] Take the above flocculants to test the purification ability of domestic sewage in a certain place. Add 1 L of domestic sewage into a container, add 100 mg of the above Flocculants 1-5, oscillate for 5 min, then let it stand for 30 min, drain the supernatant, which is denoted as the treated sewage. Test the suspended solid removal rate, turbidity removal rate and COD removal rate of the supernatant. As can be seen from Table 1 below, the flocculants prepared in Examples 1-3 have good effects in the removal performance of suspended solids, turbidity and COD, all above 90%. After the test is completed, the flocculants are sucked out by magnetic separation. The magnetism of Flocculants 1-3 is stable, and the first recovery rate is close to 100%. Flocculant 4 can only be recovered by centrifugation, and the recovery process is cumbersome with a low recovery rate. The magnetism of Flocculant 5 is unstable, and the first recovery rate is only 80%.

[0044] Table 1

[0045] Sample Suspended solid removal rate / % Turbidity removal rate / % CDO removal rate / % Flocculant 1 90.1 92.4 94.1 Flocculant 2 91.2 94.1 94.9 Flocculant 3 92.6 95.5 96.5 Flocculant 4 80.2 83.2 89.6 Flocculant 5 86.2 88.3 91.1

[0046] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A preparation method of an organic-inorganic polymer composite flocculant, characterized in that, It includes the following steps: S1. Acid-base etching of diatomite; S2. Crushing the etched diatomite and mixing it with magnetic powder, adding methanol solvent and stirring evenly, adding triethylenetetramine thereto, stirring evenly under ice-water bath and nitrogen protection, dropwise adding methyl acrylate, heating to 35 °C and reacting overnight, distilling off the solvent under reduced pressure; adding methanol again and stirring to mix evenly, dropping triethylenetetramine, reacting overnight at room temperature, distilling off the solvent under reduced pressure to obtain hyperbranched modified diatomite; S3. Using KH570 as a modifier to modify polyaluminum chloride, and polymerizing the modified polyaluminum chloride with methacryloyloxyethyltrimethylammonium chloride and maleic anhydride under the initiation of ammonium persulfate to obtain polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride; S4. Dispersing polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride and hyperbranched modified diatomite in deionized water, heating to 60 °C and stirring and reacting for 24 h, filtering, washing thoroughly with water and then drying to obtain the product.

2. The preparation method of the organic-inorganic polymer composite flocculant according to claim 1, characterized in that, The specific process of step S1 is as follows: Weigh a certain amount of diatomite and soak it in sodium hydroxide solution, keep it at a constant temperature of 40 °C for 2 h; after completion, filter, wash with water until neutral, dry and then calcine at 350-400 °C for 2-3 h to obtain a powder; soak the powder in 10% hydrochloric acid solution again, stand at room temperature for 1 h, after completion, filter, wash with water until neutral, dry and then calcine at 350-400 °C for 2-3 h.

3. The preparation method of the organic-inorganic polymer composite flocculant according to claim 1, characterized in that, In step S2, the mass ratio of diatomite to magnetic powder is 1:0.2-0.6, and the mass ratio of triethylenetetramine to diatomite is 1-3:

1.

4. The preparation method of the organic-inorganic polymer composite flocculant according to claim 1, characterized in that, In step S3, the modification of polyaluminum chloride is as follows: Add KH570 and absolute ethanol to the reaction flask, adjust the pH to 3-4, and stir for 1-2 h; ultrasonically disperse polyaluminum chloride in absolute ethanol and then add it to the reaction flask, heat under water bath and reflux for 2 h, continue to stir overnight at room temperature, centrifuge and separate, dry and reserve; among them, the mass ratio of KH570 to polyaluminum chloride is 1:

2.

5. The preparation method of the organic-inorganic polymer composite flocculant according to claim 1, characterized in that, In step S3, the molar ratio of methacryloyloxyethyltrimethylammonium chloride to maleic anhydride is 1-2:3-4, and the ratio of the modified polyaluminum chloride, ammonium persulfate to the sum of the masses of methacryloyloxyethyltrimethylammonium chloride and maleic anhydride is 30-50:0.5:

100.

6. The preparation method of the organic-inorganic polymer composite flocculant according to claim 1, characterized in that, The mass ratio of polyaluminum chloride-methacryloyloxyethyltrimethylammonium chloride-poly maleic anhydride to hyperbranched modified diatomite is 1:0.6-1.

7. An organic-inorganic polymer composite flocculant prepared by the preparation method according to any one of claims 1-6.