Preparation method and application of gel microspheres capable of efficiently adsorbing methylene blue dye

Abstract

The invention relates to the field of cationic dye sewage treatment. The preparation method comprises the following steps: respectively dissolving sodium alginate (SA), octadecyl trimethyl ammonium chloride (STAC) and poly (sodium p-styrenesulfonate) (PSSS) in deionized water to prepare solutions, then mixing the three solutions together, uniformly stirring to form a mixed solution, dropwise adding the mixed solution into a CaCl2 solution, cross-linking and curing to form microspheres, and drying the microspheres to obtain the gel microspheres (SA-PSSS-H). Taking out the microspheres, repeatedly washing the microspheres with deionized water, placing the microspheres in a hydrochloric acid solution for H < + > replacement, repeatedly washing the replaced microspheres with deionized water, and drying to constant weight to obtain the efficient methylene blue dye adsorption gel microspheres (SA (at) PSSS-H). The prepared gel microspheres capable of efficiently adsorbing the methylene blue dye have high adsorption capacity on cationic dye and can efficiently adsorb the cationic dye.

Description

Technical Field

[0001] The invention relates to the field of cationic dye wastewater treatment. Background Art

[0002] In recent years, due to the large amount of toxic substances contained in pollutants in the environment, people have paid extensive attention to them, especially the organic dyes contained in the discharged wastewater. These dyes mainly come from the textile, papermaking, dye, plastic and other industries, and are easily diffused into the environment. The discharged dyes not only reduce photosynthesis in the aquatic environment, but also easily cause water toxicity and threaten human health. Most dyes are non-biodegradable and carcinogenic, and can enter the body through drinking water, directly destroy the normal organs and tissues of the human body, and endanger the health and safety of organisms. Methylene blue MB is used in many fields, so a large amount of MB eventually enters the wastewater, posing a risk to aquatic organisms (Nguyen NB, Phan TQP, Pham CTT, Nguyen HN, Pham SN, Nguyen QKA, Nguyen DT. Journal of The Serbian Chemical Society, 2023, 88(4): 423-435). For example, the presence of dyes hinders the aesthetic quality of water and reduces the penetration of sunlight and oxygen in aquatic ecosystems, affecting the normal flow of water systems. Therefore, the removal of dyes is crucial. Commonly used methods include coagulation / flocculation, chemical precipitation, reverse osmosis, ultrafiltration, oxidation, electrochemical method, biological method, etc. Among them, adsorption method is considered to be a promising technology for wastewater treatment due to its low cost, convenient operation and strong versatility (Feng CT, Ren PG, Huo MX, Dai Z, Liang D, Jin YL, Ren F. CarbohydratePolymers, 2020, 241: 116369).

[0003] There are many kinds of materials used to prepare adsorbents. In recent years, researchers have used a variety of adsorbents such as activated carbon, zeolite, clay, biomass, functional polymer resins, and polymer hydrogels to treat dye wastewater. Although traditional adsorbents (such as activated carbon and zeolite) have been widely used to remove pollutants from sewage, their adsorption efficiency is limited, especially when treating dye wastewater. Biodegradable polymer hydrogels are favored by researchers because of their good regeneration adsorption capacity and low cost (Kubra KT, Salman MS, Znad H, Hasan M N. Journal of Molecular Liquids, 2021, 329: 115541). Biomacromolecule materials have attracted widespread attention due to their degradability, non-toxicity, and biocompatibility. Sodium alginate SA is a natural biomacromolecule, a byproduct of extracting iodine and mannitol from kelp or sargassum of brown algae. It has a wide range of sources, low prices, and green and harmless raw materials, and has broad application prospects. Sodium alginate microspheres can be modified with surfactants to give the microspheres some advantages after fusion. Microspheres were prepared by the internal gel method (Wei Tianxiang, Zhai Longyu, Jin Lili, He Hongyan. Journal of Functional Polymers, 2023, 36(06): 570-577). A composite material was obtained by cross-linking alginate / carboxymethyl cellulose on a melamine sponge, and the maximum adsorption capacity of methylene blue at pH 8 was 230 mg / g (Zeng Y, Tang XT, Qin Y, Maimaiti A, Zhou XD, Guo YJ, Liu X, Zhang WQ, Gao J, Zhang LF, International Journal of BiologicalMacromolecules, 2023, 244: 125-280). Sodium alginate is cross-linked and deposited on the surface of zeolite, and Fe3O4 nanoparticles are introduced at the same time, and the theoretical maximum adsorption capacity for methylene blue is 181.85 mg / g (Liu FJ, Li W, Zhou YS, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021, 629, 127403). However, the adsorbents prepared by these methods or operations still have a lot of room for improvement in the adsorption of methylene blue dye. Therefore, the present invention designs a sodium alginate gel microsphere with simple preparation process, low price, batch production, high repeatability, easy recovery, and strong adsorption capacity for methylene blue dye. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to provide a preparation method of gel microspheres which has simple preparation process, low price, easy recycling and high adsorption capacity for cationic methylene blue dye.

[0005] The technical scheme adopted by the present invention is: a preparation method of highly efficient methylene blue dye adsorption gel microspheres (SA@PSSS-H): sodium alginate (SA), octadecyltrimethylammonium chloride (STAC), and sodium poly(p-styrene sulfonate) (PSSS) are dissolved in deionized water to prepare a solution, and then the three solutions are mixed and stirred to form a mixed solution, and the mixed solution is added dropwise to a CaCl2 solution for cross-linking and curing to form microspheres, and the microspheres are taken out, and the microspheres are repeatedly washed with deionized water, and then the microspheres are placed in a hydrochloric acid solution for H + The replaced microspheres were repeatedly washed with deionized water and dried to constant weight to obtain highly efficient methylene blue dye adsorption gel microspheres (SA@PSSS-H).

[0006] As a preferred method: the sodium alginate, octadecyltrimethylammonium chloride, and sodium poly(p-styrene sulfonate) are dissolved in deionized water to form solutions, which means that sodium alginate is dissolved in deionized water to form a solution with a mass percentage concentration of 1-4%, octadecyltrimethylammonium chloride is dissolved in deionized water to form a solution with a mass percentage concentration of 2-8%, and sodium poly(p-styrene sulfonate) is dissolved in deionized water to form a solution with a mass percentage concentration of 1-4%; when the three solutions are mixed together, the mass ratio of the sodium alginate solution, the octadecyltrimethylammonium chloride solution, and the sodium poly(p-styrene sulfonate) solution is 5:1:1.

[0007] As a preferred method: the mixed solution is added dropwise to a CaCl2 solution for cross-linking and curing to form microspheres. Specifically, the mixed solution is slowly dropped into a CaCl2 solution with a mass percentage concentration of 1-4% using a syringe, and the solution is allowed to stand for cross-linking and curing for 24 hours to form microspheres.

[0008] As a preferred method: the concentration of hydrochloric acid solution is 0.02~0.05 mol / L, H + The replacement time is 2h.

[0009] As a preferred method: repeated washing with deionized water means washing with deionized water 2-5 times.

[0010] The invention discloses an application of gel microspheres capable of efficiently absorbing methylene blue dye. The gel microspheres capable of efficiently absorbing methylene blue dye are used to absorb cationic dyes in wastewater, wherein the cationic dye is methylene blue.

[0011] The beneficial effects of the present invention are as follows: (1) the biocompatible polysaccharide sodium alginate SA carrying a large amount of anions and the polyanion electrolyte poly(p-styrene sulfonate) PSSS are reacted in the presence of Ca2+ In the presence of cross-linking into three-dimensional network gel microspheres, the gel microspheres carry a large number of anions and can form electrostatic interactions with cationic dyes. The multi-fold sodium alginate / poly (sodium p-styrene sulfonate) gel microspheres SA@PSSS-H are prepared by replacing octadecyltrimethylammonium chloride in the gel microspheres with hydrochloric acid. (2) The gel microspheres SA@PSSS-H prepared by the present invention have good mechanical properties and high water absorption performance, with a water absorption rate of 172%; they have a high adsorption capacity for cationic dyes and can efficiently adsorb cationic dyes, especially the adsorption capacity of methylene blue reaches 886.77 mg / g. (3) The preparation process of the present invention is simple, the raw material source is widely available, the production cost is low, the operability is strong, it is easy to control, and the material is easy to recycle after use. It has good application prospects in the field of cationic dye wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the wet-sphere diagram of the gel microspheres with high efficiency in adsorbing methylene blue dye; Figure 2 Yes H + Comparison of the adsorption amount of methylene blue by gel microspheres with high efficiency of adsorbing methylene blue dye before and after replacement. DETAILED DESCRIPTION

[0013] Example 1: Deionized water was used to prepare solutions with a mass percentage concentration of 3% sodium alginate, 2% octadecyltrimethylammonium chloride, and 4% sodium poly(p-styrene sulfonate), respectively, and then the above three solutions were mixed in a mass ratio of 5:1:1, and stirred at a constant speed at room temperature until a uniform mixed solution was formed. After the mixed solution was allowed to stand for degassing, the mixed solution was extracted with a syringe and slowly and uniformly dripped into a CaCl2 solution with a mass percentage concentration of 3%, and cross-linked and cured for 24 h. The prepared microspheres were rinsed with deionized water three times, the surface of the microspheres were wiped dry with filter paper, and then the microspheres were placed in a 0.05 mol / L hydrochloric acid solution and stirred at a constant speed for 2 h. + Replacement. Rinse the replaced microspheres three times with deionized water, wipe the surface of the microspheres with filter paper, and dry them in an oven until the microspheres have a constant weight. + The highly efficient adsorption of methylene blue dye gel microspheres SA@PSSS-H after replacement, such as Figure 1 0.02 g of highly efficient methylene blue dye adsorption gel microspheres SA@PSSS-H were accurately weighed into a conical flask, and 20 mL of methylene blue solution with an initial concentration of 800 mg / L, pH of 7.0, and salinity of 0% was added. The solution was placed in a constant temperature oscillator and oscillated at 45 °C for 6 h. The saturated adsorption capacity reached 886.77 mg / g.

[0014] Example 2: Deionized water was used to prepare solutions with a mass percentage concentration of 1% sodium alginate, 8% octadecyltrimethylammonium chloride, and 4% sodium poly(p-styrene sulfonate), respectively, and then the above three solutions were mixed at a mass ratio of 5:1:1 and stirred at a constant temperature and uniform speed until a uniform mixed solution was formed. The mixed solution needs to be allowed to stand for degassing, and then the mixed solution is extracted with a syringe with a needle and slowly dripped into a CaCl2 solution with a mass percentage concentration of 4%, and cross-linked and cured for 24 hours. The prepared microspheres were rinsed with deionized water twice, the surface of the microspheres were wiped dry with filter paper, and then the microspheres were placed in a 0.05 mol / L hydrochloric acid solution and stirred at a uniform speed for 2 hours. + Replacement. Rinse the replaced microspheres three times with deionized water, wipe the surface of the microspheres with filter paper, and dry them in an oven until the microspheres have a constant weight. + The highly efficient adsorption of methylene blue dye gel microspheres SA@PSSS-H after replacement, such as Figure 1 As shown. 0.02 g of highly efficient methylene blue dye adsorption gel microspheres SA@PSSS-H were accurately weighed into a conical flask, and 20 mL of methylene blue solution with an initial concentration of 800 mg / L, pH of 7.0, and salinity of 0% was added. The solution was placed in a constant temperature oscillator and oscillated at 25 °C for 6 h. The saturated adsorption capacity can reach 549.90 mg / g, as shown in Figure 2 As shown, it can be seen that H + There was a significant difference in the adsorption amount of methylene blue by the gel microspheres with high efficiency of adsorbing methylene blue dye before and after replacement.

[0015] Example 3: Deionized water was used to prepare 3% sodium alginate, 2% octadecyltrimethylammonium chloride, and 4% sodium poly(p-styrene sulfonate) solutions, and then the three solutions were mixed at a mass ratio of 5:1:1 and stirred at a constant temperature until a uniform mixed solution was formed. The mixed solution was allowed to stand for degassing, and then the mixed solution was extracted with a syringe and slowly and uniformly dripped into a 3% CaCl2 solution for cross-linking and curing for 24 h. The prepared microspheres were rinsed 4 times with deionized water, the surface of the microspheres were wiped dry with filter paper, and then the microspheres were placed in a 0.05 mol / L hydrochloric acid solution and stirred at a constant speed for 2 h. + Replacement. Rinse the replaced microspheres twice with deionized water, wipe the surface moisture of the microspheres with filter paper, and dry them in an oven at 50°C until the microspheres have a constant weight. + The highly efficient adsorption of methylene blue dye gel microspheres SA@PSSS-H after replacement, such as Figure 10.02 g of highly efficient methylene blue dye adsorption gel microspheres SA@PSSS-H were accurately weighed into a conical flask, and 20 mL of methylene blue solution with an initial concentration of 800 mg / L, pH of 7.0, and salinity of 0% was added. The solution was placed in a constant temperature oscillator and oscillated at 25°C for 6 h. The saturated adsorption capacity reached 786.90 mg / g.

[0016] Example 4: Deionized water was used to prepare 3% sodium alginate, 2% octadecyltrimethylammonium chloride, and 4% sodium poly(p-styrene sulfonate) solutions, and then the three solutions were mixed at a mass ratio of 5:1:1 and stirred at a constant temperature until a uniform mixed solution was formed. The mixed solution was allowed to stand for degassing, and then the mixed solution was extracted with a syringe and slowly and uniformly dripped into a 3% CaCl2 solution, and cross-linked and cured for 24 h. The prepared microspheres were rinsed with deionized water 5 times, the surface of the microspheres were wiped dry with filter paper, and then the microspheres were placed in a 0.05 mol / L hydrochloric acid solution and stirred at a constant speed for 2 h. + Replacement. Rinse the replaced microspheres 5 times with deionized water, wipe the surface of the microspheres with filter paper, and dry them in an oven at 40°C until the microspheres have a constant weight. + The highly efficient adsorption of methylene blue dye gel microspheres SA@PSSS-H after replacement, such as Figure 1 0.02 g of highly efficient methylene blue dye adsorption gel microspheres SA@PSSS-H were accurately weighed into a conical flask, and 20 mL of methylene blue solution with an initial concentration of 800 mg / L, pH of 7.0, and salinity of 1% was added. The solution was placed in a constant temperature oscillator and oscillated at 25°C for 6 h. The saturated adsorption capacity could reach 300.91 mg / g.

[0017] Example 5: Deionized water was used to prepare 3% sodium alginate, 2% octadecyltrimethylammonium chloride, and 4% sodium poly(p-styrene sulfonate) solutions, and then the three solutions were mixed at a mass ratio of 5:1:1 and stirred at a constant temperature until a uniform mixed solution was formed. The mixed solution was allowed to stand for degassing, and then the mixed solution was extracted with a syringe and slowly and uniformly dripped into a 3% CaCl2 solution, and cross-linked and cured for 24 h. The prepared microspheres were rinsed 4 times with deionized water, the surface of the microspheres were wiped dry with filter paper, and then the microspheres were placed in a 0.05 mol / L hydrochloric acid solution and stirred at a constant speed for 2 h. + Replacement. Rinse the replaced microspheres 4 times with deionized water, wipe the surface moisture of the microspheres with filter paper, and dry them in an oven until the microspheres have a constant weight. + The highly efficient adsorption of methylene blue dye gel microspheres SA@PSSS-H after replacement, such as Figure 10.02 g of highly efficient methylene blue dye adsorption gel microspheres SA@PSSS-H were accurately weighed into a conical flask, and 20 mL of methylene blue solution with an initial concentration of 800 mg / L, pH of 4.0, and salinity of 0% was added. The solution was placed in a constant temperature oscillator and oscillated at 25°C for 6 h. The saturated adsorption capacity reached 658.96 mg / g.

Claims

1. A method for preparing gel microspheres with high efficiency in adsorbing methylene blue dye, characterized in that: Sodium alginate, octadecyltrimethylammonium chloride, and sodium poly(p-styrene sulfonate) were dissolved in deionized water to prepare solutions, and then the three solutions were mixed and stirred to form a mixed solution. The mixed solution was added dropwise to a CaCl2 solution for cross-linking and solidification to form microspheres. The microspheres were taken out, and after repeatedly washing the microspheres with deionized water, the microspheres were placed in a hydrochloric acid solution for H + The replaced microspheres are repeatedly washed with deionized water and dried to a constant weight to obtain gel microspheres with high efficiency in adsorbing methylene blue dye.

2. The method for preparing a highly efficient methylene blue dye adsorption gel microsphere according to claim 1, characterized in that: Said dissolving sodium alginate, octadecyltrimethylammonium chloride and sodium poly(p-styrene sulfonate) in deionized water respectively to prepare solutions means that sodium alginate is dissolved in deionized water to prepare a solution with a mass percentage concentration of 1-4%, octadecyltrimethylammonium chloride is dissolved in deionized water to prepare a solution with a mass percentage concentration of 2-8%, and sodium poly(p-styrene sulfonate) is dissolved in deionized water to prepare a solution with a mass percentage concentration of 1-4%; when the three solutions are mixed together, the mass ratio of the sodium alginate solution, the octadecyltrimethylammonium chloride solution and the sodium poly(p-styrene sulfonate) solution is 5:1:

1.

3. The method for preparing a highly efficient methylene blue dye adsorption gel microsphere according to claim 1, characterized in that: The mixed solution is added dropwise into a CaCl2 solution for cross-linking and curing to form microspheres. Specifically, the mixed solution is slowly dropped into a CaCl2 solution with a mass percentage concentration of 1-4% by using a syringe, and the solution is allowed to stand for cross-linking and curing for 24 hours to form microspheres.

4. The method for preparing a highly efficient methylene blue dye adsorption gel microsphere according to claim 1, characterized in that: The concentration of hydrochloric acid solution is 0.02~0.05 mol / L, H + The replacement time is 2h.

5. The method for preparing a highly efficient methylene blue dye adsorption gel microsphere according to claim 1, characterized in that: Repeated washing with deionized water means washing with deionized water 2-5 times.

6. An application of gel microspheres with high efficiency in adsorbing methylene blue dye prepared by the preparation method of claim 1, characterized in that: The high-efficiency methylene blue dye adsorption gel microspheres are used to adsorb cationic dyes in wastewater, wherein the cationic dye is methylene blue.

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