Preparation method and application of functional microspheres capable of efficiently adsorbing anionic dye

Abstract

The invention relates to the technical field of preparation methods and application of functional microspheres for filtering and adsorbing anionic dyes in a water system, in particular to a preparation method and application of grafted polymethylacryloyloxyethyl trimethyl ammonium chloride cross-linked chitosan functional microspheres for efficiently adsorbing anionic dyes. Amino groups (-NH2) on the surfaces of the cross-linked chitosan microspheres and ammonium persulfate (APS) in an aqueous solution form a redox system, and methylacryloyloxyethyl trimethyl ammonium chloride is initiated to be subjected to graft polymerization to the cross-linked chitosan microspheres, so that the grafted polymethylacryloyloxyethyl trimethyl ammonium chloride cross-linked chitosan functional microspheres GCS-g-PDMC are prepared. The functional microspheres prepared by the method have high adsorption capacity on anionic dyes such as methyl orange, acid orange 7, sunset yellow and amaranth.

Description

Technical Field

[0001] The invention relates to the field of filtration and adsorption of anionic dyes in water systems, and in particular to the preparation and application of functional grafted microspheres for efficiently adsorbing methyl orange, acid orange 7, sunset yellow and amaranth. Background Art

[0002] Organic dyes are widely used in many industrial fields due to their bright colors, excellent color fastness, and ease of use. The global annual production of dyes is about 700,000 tons, and the textile industry alone discharges about 5-15% of dyes into the waste stream. The presence of dyes in water is a serious environmental problem due to their toxic, carcinogenic, and mutagenic effects on aquatic species and humans. In order to remove dyes from wastewater, various treatment technologies have been studied, including coagulation, electrochemistry, photocatalytic degradation, adsorption, and filtration (Abdallah and Alprol, Science Reports, 2024, 14:13012). Among them, adsorption is a preferred method because of its advantages such as easy availability, simple design, and convenient operation. Moreover, most adsorption processes are reversible, so the adsorbent can be easily regenerated for reuse using a suitable desorption process. Many types of adsorbents have been used to remove organic dyes, such as activated carbon, nanoadsorbents, polymer absorbents, and biosorbents ( Choi WS , Lee HJ , Polymers , 2022 , 14:2183 ). However, the development of low-cost, easy-to-prepare, and efficient adsorbents remains a problem and challenge in dye adsorption applications.

[0003] Chitosan is a polysaccharide of N-acetyl-d-glucosamine and d-glucosamine produced by deacetylation of chitin and is one of the most abundant biopolymers. Chitosan has been widely studied as a potential adsorbent for dye removal due to its good combination of properties, such as non-toxicity, low cost, biodegradability and a large number of hydroxyl and amino functional groups. The active sites such as amino and hydroxyl groups on chitosan make it a good adsorbent for interacting with anionic dyes. Yipeng Zhang et al. used pure chitosan beads to adsorb the anionic dye Congo red, with an adsorption amount of 11.9 mg / g, and the adsorption capacity of pure chitosan beads was low. In order to increase the adsorption amount, modifying chitosan-based adsorbents by post-treatment or in-situ blending is a promising method to improve the adsorption capacity. Wang QQ et al. (Wang et al., International Journal of BiologicalMacromolecules, 2023, 253:126631) grafted diethylenetriamine pentaacetate onto Fe 3 O 4A magnetically recyclable dye adsorbent was synthesized on a composite material of microspheres and cross-linked chitosan for the removal of the dye methyl orange (MO) from aqueous solution. After modification, the adsorption capacity was greatly improved. The modified chitosan not only retains the high specific surface area, a large number of functional groups, and environmental friendliness of the chitosan cross-linked microspheres themselves, but also can adjust the surface charge and structural characteristics through the modification method. Therefore, exploring suitable modified materials and methods is still the research route for the preparation of new chitosan-based adsorbents.

[0004] The invention designs chitosan microspheres with a simple preparation process, low price and environmental friendliness, which carry a large number of cationic functional groups on the surface. In a water system, a "one-step method" is adopted to graft polymerize polymethacryloyloxyethyltrimethylammonium chloride on the surface of cross-linked chitosan microspheres to obtain functional microspheres with a large number of cations on the surface, which show strong adsorption capacity for anionic dyes. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to provide a preparation method and application of functional microspheres which have simple preparation process, low price, green synthesis and can show high adsorption capacity for anionic dyes.

[0006] The technical scheme adopted by the present invention is: a method for preparing functional microspheres with high efficiency in adsorbing anionic dyes, comprising the steps of soaking cross-linked chitosan microspheres (GCS) in water to swell, adding a functional monomer methacryloyloxyethyl trimethylammonium chloride (DMC) solution, stirring evenly under nitrogen protection, heating to 30-70°C, adding an initiator ammonium persulfate solution, carrying out a graft polymerization reaction under nitrogen protection, washing with water, filtering, and vacuum drying to constant weight after the reaction is complete (reaction time 5-9 h), and obtaining grafted microspheres GCS-g-PDMC, i.e., functional microspheres with high efficiency in adsorbing anionic dyes.

[0007] When preparing the functional monomer methacryloyloxyethyltrimethylammonium chloride (DMC) solution, add 3.8~11.4 mL of the monomer methacryloyloxyethyltrimethylammonium chloride DMC to every 40 mL of water; stirring evenly under nitrogen protection means stirring for 30 minutes or more under nitrogen protection; when preparing the initiator ammonium persulfate solution, add 0.039~0.195g of ammonium persulfate to every 6 mL of water.

[0008] Every 0.4 g of cross-linked chitosan microspheres requires 3.8~11.4 mL of the functional monomer methacryloyloxyethyltrimethylammonium chloride (DMC) and 0.039~0.195 g of ammonium persulfate.

[0009] The invention discloses an application of functional microspheres for efficiently adsorbing anionic dyes. The functional microspheres for efficiently adsorbing anionic dyes are used for adsorbing anionic dyes.

[0010] The anionic dyes are adsorbed methyl orange, acid orange 7, sunset yellow and amaranth red.

[0011] The beneficial effects of the present invention are as follows: (1) GCS-g-PDMC is prepared by grafting a polymer polymethacryloyloxyethyl trimethyl ammonium chloride on the surface of cross-linked chitosan microspheres as a matrix, and GCS-g-PDMC is used as a functional microsphere to adsorb anionic dyes. The grafted functional microspheres prepared by the method have a very high adsorption capacity for anionic dyes and can efficiently adsorb anionic dyes. The adsorption capacity of the grafted functional microspheres prepared by the method for methyl orange, acid orange 7, sunset yellow, and amaranth red can reach 842 mg / g, 897 mg / g, 616 mg / g, and 621 mg / g. (2) The preparation process of the present invention uses cross-linked chitosan microspheres as a matrix, and has the green and harmless nature of cross-linked chitosan, good biocompatibility, biodegradability, and non-toxicity, and has a wide source and is suitable for the requirements of industrial production. The preparation process is simple, low cost, easy to control, and the synthesis process can be completed entirely in an aqueous solution. (3) The present invention constructs a redox initiation system in the matrix microspheres and the solution to initiate the grafting polymerization of functional monomers onto the matrix microspheres under mild conditions to obtain grafted microspheres with high adsorption performance. The amino groups on the cross-linked chitosan (GCS) and the ammonium persulfate in the solution form a redox initiation system to initiate the grafting polymerization of the monomer methacryloyloxyethyltrimethylammonium chloride (DMC) onto the surface of the cross-linked chitosan microspheres, forming a high-performance grafted functional microsphere GCS-g-PDMC. The preparation method is simple, easy to operate, mild in conditions, pollution-free, low in price, and has strong adsorption capacity for anionic dyes. DETAILED DESCRIPTION

[0012] Example 1: In a four-necked bottle, 0.4 g of cross-linked chitosan microspheres (GCS) were soaked in 30 mL of purified water for 12 h, and then 9.5 mL of methacryloyloxyethyltrimethylammonium chloride (DMC) was dissolved in 40 mL of purified water and added to the four-necked bottle. The mixture was stirred and purged with N 2 After 30 min, the temperature was raised to 50 °C, and 6 mL of aqueous solution containing 0.156 g of ammonium persulfate (Aps) was slowly added. The graft polymerization reaction was carried out under nitrogen protection for 7 h. After the reaction was completed, it was washed with water, filtered, and vacuum dried to obtain the grafted microspheres GCS-g-PDMC. 50 mL of methyl orange, acid orange 7, sunset yellow, and amaranth red solutions with an initial concentration of 1 mg / mL and a pH of 7.0 were added to a precisely weighed 0.05 g of grafted microspheres GCS-g-PDMC in a stoppered conical bottle, placed in a constant temperature oscillator, and oscillated at a constant temperature of 25 °C for 3 h. The saturated adsorption amounts can reach 842 mg / g, 897 mg / g, 616 mg / g, and 621 mg / g, respectively.

[0013] Example 2: In a four-necked bottle, 0.4 g of cross-linked chitosan microspheres (GCS) were soaked in 30 mL of purified water for 12 h, and then 11.4 mL of methacryloyloxyethyltrimethylammonium chloride (DMC) was dissolved in 40 mL of purified water and added to the four-necked bottle. The mixture was stirred and purged with N 2 After 30 min, the temperature was raised to 50 °C, and 6 mL of aqueous solution containing 0.195 g of ammonium persulfate (Aps) was slowly added. The graft polymerization reaction was carried out under nitrogen protection for 9 h. After the reaction was completed, it was washed with water, filtered, and vacuum dried to obtain the grafted microspheres GCS-g-PDMC. 50 mL of methyl orange, acid orange 7, sunset yellow, and amaranth red solutions with an initial concentration of 1 mg / mL and a pH of 7.0 were added to a conical flask containing 0.05 g of grafted microspheres GCS-g-PDMC, respectively, and placed in a constant temperature oscillator and oscillated at 25 °C for 3 h. The saturated adsorption amounts can reach 778 mg / g, 710 mg / g, 608 mg / g, and 491 mg / g, respectively.

[0014] Example 3: In a four-necked bottle, 0.4 g of cross-linked chitosan microspheres (GCS) were soaked in 30 mL of purified water for 12 h, and then 3.8 mL of methacryloyloxyethyltrimethylammonium chloride (DMC) was dissolved in 40 mL of purified water and added to the four-necked bottle. The mixture was stirred and purged with N 2 After 30 min, the temperature was raised to 50 °C, and 10 mL of aqueous solution containing 0.039 g of ammonium persulfate (Aps) was slowly added. The graft polymerization reaction was carried out under nitrogen protection for 7 h. After the reaction was completed, it was washed with water, filtered, and vacuum dried to obtain the grafted microspheres GCS-g-PDMC. 50 mL of methyl orange, acid orange 7, sunset yellow, and amaranth red solutions with an initial concentration of 1 mg / mL and a pH of 7.0 were added to a precisely weighed 0.05 g of grafted microspheres GCS-g-PDMC in a stoppered conical flask, placed in a constant temperature oscillator, and oscillated at a constant temperature of 25 °C for 3 h. The saturated adsorption amounts can reach 497 mg / g, 388 mg / g, 357 mg / g, and 545 mg / g, respectively.

[0015] Example 4: In a four-necked bottle, 0.4 g of cross-linked chitosan microspheres (GCS) were soaked in 30 mL of purified water for 12 h, and then 5.7 mL of methacryloyloxyethyltrimethylammonium chloride (DMC) was dissolved in 40 mL of purified water and added to the four-necked bottle. The mixture was stirred and purged with N 2After 30 min, the temperature was raised to 50 °C, and 10 mL of aqueous solution containing 0.059 g of ammonium persulfate (Aps) was slowly added. The graft polymerization reaction was carried out under nitrogen protection for 5 h. After the reaction was completed, it was washed with water, filtered, and vacuum dried to obtain the grafted microspheres GCS-g-PDMC. 50 mL of methyl orange, acid orange 7, sunset yellow, and amaranth red solutions with an initial concentration of 1 mg / mL and a pH of 7.0 were added to a conical flask containing 0.05 g of grafted microspheres GCS-g-PDMC, respectively, and placed in a constant temperature oscillator and oscillated at 25 °C for 3 h. The saturated adsorption amounts can reach 690 mg / g, 710 mg / g, 561 mg / g, and 503 mg / g, respectively.

Claims

1. A method for preparing functional microspheres for efficient adsorption of anionic dyes, characterized in that: After the cross-linked chitosan microspheres are soaked in water to swell, a functional monomer methacryloyloxyethyl trimethyl ammonium chloride DMC solution is added, and the mixture is stirred evenly under nitrogen protection. The temperature is raised to 30-70°C, and an initiator ammonium persulfate solution is added. A graft polymerization reaction is carried out under nitrogen protection. After the reaction is complete, the mixture is washed with water, filtered, and vacuum dried to a constant weight to obtain grafted microspheres GCS-g-PDMC, i.e., functional microspheres for efficient adsorption of anionic dyes.

2. The method for preparing functional microspheres for efficiently adsorbing anionic dyes according to claim 1, characterized in that: When preparing the functional monomer methacryloyloxyethyltrimethylammonium chloride DMC solution, add 3.8~11.4 mL of the monomer methacryloyloxyethyltrimethylammonium chloride DMC to every 40 mL of water; stirring evenly under nitrogen protection means stirring for 30 minutes or more under nitrogen protection; when preparing the initiator ammonium persulfate solution, add 0.039~0.195g of ammonium persulfate to every 6 mL of water.

3. The method for preparing functional microspheres for efficiently adsorbing anionic dyes according to claim 1, characterized in that: Every 0.4 g of cross-linked chitosan microspheres requires 3.8~11.4 mL of the functional monomer methacryloyloxyethyltrimethylammonium chloride DMC and 0.039~0.195 g of ammonium persulfate.

4. An application of the highly efficient anionic dye adsorption functional microspheres prepared by the method for preparing highly efficient anionic dye adsorption functional microspheres as claimed in claim 1, characterized in that: Functional microspheres with high efficiency in adsorbing anionic dyes are used to adsorb anionic dyes.

5. The use of a functional microsphere for efficiently adsorbing anionic dyes according to claim 4, characterized in that: The anionic dyes are adsorbed methyl orange, acid orange 7, sunset yellow and amaranth red.