High-temperature-resistant ion exchange resin for sewage treatment and preparation method thereof

Abstract

The application discloses a kind of sewage treatment high-temperature-resistant ion exchange resin and preparation method thereof, belong to ion exchange resin preparation field, for solving in prior art anion exchange resin, under high-temperature sewage treatment condition, there is poor thermal stability and exchange capacity needs to be further improved technical problem, specifically includes: macroporous hybrid polyether sulfone microspheres and ethanol are placed in closed reaction kettle, stirring 1-2h at room temperature, add trimethylamine aqueous solution, reaction kettle is heated to 40-50 DEG C, and heat preservation reaction 12-18h, aftertreatment obtains anion exchange resin.The application is with chloromethylation polystyrene as core, polyethyleneimine size exclusion effect grafts retention benzyl chloride, silica anchoring and polyether sulfone coupling constructs inorganic skeleton and heat-resistant shell, trimethylamine quaternization transformation, improve the high-temperature-resistant performance and exchange capacity of ion exchange resin.

Description

Technical Field

[0001] This invention relates to the field of ion exchange resin preparation, and specifically to a high-temperature resistant ion exchange resin for wastewater treatment and its preparation method. Background Technology

[0002] As a core functional material in the field of water treatment, the high temperature resistance and mechanical stability of ion exchange resins have always been key technical indicators in industrial applications. With the increasing prevalence of high-temperature wastewater treatment conditions, traditional polystyrene-based anion exchange resins face prominent problems such as skeleton thermal creep, functional group degradation, and mechanical strength decay in high-temperature aqueous environments. In recent years, researchers have improved the heat distortion temperature and compressive strength of resins to some extent by increasing the degree of crosslinking, introducing rigid heterocyclic monomers, or hybridizing with inorganic nanoparticles. However, under long-term high-temperature hydrothermal coupling, the stability of deep functional sites and the integrity of interface structure of the resin are still difficult to meet the requirements of harsh working conditions.

[0003] Industrially used high-temperature ion exchange resins are mostly prepared by introducing quaternary ammonium groups after chloromethylation of styrene-divinylbenzene copolymer as the backbone. To improve its heat resistance, common modification methods include introducing rigid comonomers such as acrylonitrile during the polymerization stage to improve the rigidity of the backbone. In addition, engineering plastics are used to coat or coat the resin surface in an attempt to build a heat-resistant barrier on the outer layer of the resin. However, among the above methods, surface coating has problems such as poor coating continuity and easy swelling and peeling.

[0004] Currently, when performing surface functionalization modification on chloromethylated polystyrene microspheres, small molecule amines or multifunctional compounds are usually used to undergo nucleophilic substitution reactions with benzyl chloride. Since small molecule modifiers can freely diffuse into the deep pores of the macroporous framework, benzyl chloride is indiscriminately consumed on the surface and inside of the framework, resulting in insufficient active sites for subsequent quaternization reactions. Ultimately, the exchange capacity of the resin is significantly reduced. At the same time, in traditional inorganic hybrid technology, the inorganic phase and organic framework rely on single chemical bonds or physical adsorption for bonding, resulting in insufficient interfacial bonding site density. Under long-term action in a high-temperature aqueous phase, interfacial peeling is prone to occur, making it difficult to achieve a substantial improvement in mechanical strength.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a high-temperature resistant ion exchange resin for wastewater treatment and its preparation method, in order to solve the technical problems of poor thermal stability and the need to further improve the exchange capacity of existing anion exchange resins under high-temperature wastewater treatment conditions.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing a high-temperature resistant ion exchange resin for wastewater treatment, comprising the following steps:

[0008] S1. Macroporous chloromethylated polystyrene and N,N-dimethylformamide are placed in a reaction vessel under nitrogen atmosphere protection and stirred at room temperature for 2-4 hours. Branched polyethyleneimine is added, the reaction vessel is heated to 60-75℃, and the reaction is maintained for 6-8 hours. Epoxy-modified silicon spheres are added, the reaction vessel is heated to 80-90℃, and the reaction is maintained for 12-16 hours. Post-treatment yields macroporous hybrid microspheres.

[0009] S2. Place macroporous hybrid microspheres, hydroxyl-terminated polyethersulfone, N-methylpyrrolidone, p-toluenesulfonyl chloride and potassium carbonate in a reaction vessel and stir. Heat the reaction vessel to 80-100℃ and keep it at that temperature for 18-24 hours. After post-treatment, macroporous hybrid polyethersulfone microspheres are obtained.

[0010] S3. Place macroporous hybrid polyethersulfone microspheres and ethanol in a sealed reactor and stir at room temperature for 1-2 hours. Add trimethylamine aqueous solution, heat the reactor to 40-50℃, and keep the reaction at this temperature for 12-18 hours. Post-treatment yields anion exchange resin.

[0011] Further, in step S1, the ratio of macroporous chloromethylated polystyrene, N,N-dimethylformamide, and branched polyethyleneimine is 20-40g:300-500mL:2-4g, and the molar amount of epoxy-modified silica spheres is 0.3 times the total molar amount of amino groups in the branched polyethyleneimine. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to a vacuum drying oven at 60-70℃, and dried for 10-12 hours to obtain macroporous hybrid microspheres.

[0012] Further, in step S2, the ratio of macroporous hybrid microspheres, hydroxyl-terminated polyethersulfone, N-methylpyrrolidone, p-toluenesulfonyl chloride, and potassium carbonate is 20-40g:3-8g:200-400mL:0.5-1g:0.5-1g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, and the filter cake is washed 1-3 times with deionized water and ethanol at 40-50℃, respectively, and transferred to a vacuum drying oven at 70-80℃ for vacuum drying for 20-24h to obtain macroporous hybrid polyethersulfone microspheres.

[0013] Further, in step S3, the ratio of macroporous hybrid polyethersulfone microspheres, ethanol, and trimethylamine aqueous solution is 30-40g:200-300mL:100-150mL, the concentration of trimethylamine aqueous solution is 30-40wt%, and the autogenous pressure in the sealed reactor is maintained at 0.1-0.3MPa. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with deionized water 1-3 times, the washed resin is immersed in 1mol / L sodium hydroxide solution for 2-4h, washed with deionized water until neutral, transferred to a vacuum drying oven at 45-55℃, and vacuum dried for 20-24h to obtain anion exchange resin.

[0014] Furthermore, the macroporous chloromethylated polystyrene is prepared by the following steps:

[0015] A1. Styrene, N-vinylcarbazole, divinylbenzene, toluene, n-heptane and benzoyl peroxide are placed in a reaction vessel and stirred evenly to obtain a ternary copolymer mixed monomer oil phase;

[0016] A2. Deionized water, polyvinyl alcohol, gelatin and sodium chloride are placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel is heated to 55-65℃ and stirred for 0.5-1h. Then, the ternary copolymer mixed monomer oil phase is added. The reaction vessel is heated to 75-85℃ and reacted for 2-3h. The reaction vessel is then heated to 85-95℃ and reacted for 6-8h. After post-treatment, macroporous chloromethylated polystyrene microspheres are obtained.

[0017] The reaction formula for preparing macroporous chloromethylated polystyrene microspheres is as follows:

[0018]

[0019] A3. Place macroporous chloromethylated polystyrene microspheres and 1,2-dichloroethane in a reaction vessel and stir for 4-6 hours. Add paraformaldehyde and anhydrous zinc chloride. Keep the reaction vessel in an ice bath at 0-5°C. Slowly add thionyl chloride, controlling the addition to be completed in 1-1.5 hours. After the addition is complete, remove the ice bath and slowly heat the reaction vessel to 40-45°C. Maintain the temperature for 10-12 hours. Post-process to obtain macroporous chloromethylated polystyrene.

[0020] Furthermore, in step A1, the ratio of styrene, N-vinylcarbazole, divinylbenzene, toluene, n-heptane, and benzoyl peroxide is 80-100g:5-15g:5-15g:35-70mL:30-60mL:0.5-2g.

[0021] Furthermore, in step A2, the ratio of deionized water, polyvinyl alcohol, gelatin, sodium chloride, and the ternary copolymer mixed monomer oil phase is 300-500mL:2-4g:1-2g:8-15g:80-120g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with deionized water and ethanol 2-4 times, transferred to an oven at 50-60℃, and dried for 20-24 hours to obtain macroporous chloromethylated polystyrene microspheres.

[0022] Further, in step A3, the ratio of macroporous chloromethylated polystyrene microspheres, 1,2-dichloroethane, paraformaldehyde, anhydrous zinc chloride, and thionyl chloride is 8-10g:50-100mL:5-15g:3-8g:10-20mL, and the dropping rate of thionyl chloride is controlled at 10-20mL / h. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, and the reaction solution is slowly poured into 500mL of ice water to quench the residual thionyl chloride. The microspheres are collected by suction filtration, and the filter cake is washed 1-3 times in sequence with 5% hydrochloric acid aqueous solution, deionized water, and anhydrous ethanol until the washing solution is neutral. The filter cake is then transferred to a vacuum drying oven at 50-60℃ and dried for 20-24h to obtain macroporous chloromethylated polystyrene.

[0023] Furthermore, the preparation method of the epoxy-modified silica spheres is as follows: mesoporous silica nanospheres, ethanol and deionized water are placed in a reaction vessel under nitrogen atmosphere and stirred. 3-glycidyl etheroxypropyltrimethoxysilane is added and stirred at room temperature for 3-5 min. An aqueous acetic acid solution is added to adjust the pH to 5.5-6.5. The reaction vessel is heated to 35-45℃ and kept at this temperature for 2-4 h. The epoxy-modified silica spheres are then obtained after post-treatment.

[0024] Furthermore, the ratio of the mesoporous silica nanospheres, ethanol, deionized water, and 3-glycidyl etheroxypropyltrimethoxysilane is 5-15g:100-300mL:5-15mL:2-6g, and the concentration of the acetic acid aqueous solution is 3-5wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with ethanol and deionized water 1-4 times in sequence, and then transferred to a vacuum drying oven at a temperature of 55-65℃ for drying for 20-24h to obtain epoxy-modified silica nanospheres.

[0025] The present invention also proposes a high-temperature resistant ion exchange resin for wastewater treatment, which is prepared by the above-mentioned preparation method of a high-temperature resistant ion exchange resin for wastewater treatment.

[0026] The present invention has the following beneficial effects:

[0027] 1. The high-temperature resistant ion exchange resin for wastewater treatment prepared in this invention has a macroporous chloromethylated polystyrene skeleton modified with branched polyethyleneimine. Utilizing the size exclusion effect of macromolecules, it selectively bonds to the outer surface and shallow benzyl chloride of microspheres, thus preserving the deep functional sites intact. Simultaneously, the high-density terminal amine groups of the branched polyethyleneimine form a multifunctional reaction network on the surface of the microspheres, providing grafting sites for anchoring epoxy-modified silicon spheres and reserving reactive activity for interfacial coupling of hydroxyl-terminated polyethersulfone. Thus, it achieves the dual functions of site protection and interfacial bridging within the same modified layer, providing functional sites for subsequent quaternization.

[0028] 2. The high-temperature resistant ion exchange resin for wastewater treatment prepared by this invention comprises epoxy-modified silicon spheres covalently anchored to a polystyrene framework via a branched polyethyleneimine amine ring-opening reaction, introducing inorganic rigid nodes into the organic network, resulting in a significant improvement in the resin's crushing strength. Furthermore, after activation, the terminal hydroxyl polyethersulfone undergoes nucleophilic substitution with the residual amine groups of polyethyleneimine, constructing a dense, highly thermally stable coating layer on the outer layer of the microspheres. This polyethersulfone shell and the internal inorganic nodes form a continuous interface via polyethyleneimine bridges, resulting in structural synergy between the outer heat-resistant barrier and the inner rigid framework, effectively inhibiting the thermal degradation of the framework and the loss of functional groups in a high-temperature aqueous phase.

[0029] 3. The high-temperature resistant ion exchange resin for wastewater treatment prepared by this invention has a composite heat-resistant barrier formed by the polyethersulfone shell of the microspheres and the inorganic silica nodes. This barrier protects the deep benzyl chloride from high-temperature aqueous phase corrosion. The deep sites retained by the size exclusion of the branched polyethyleneimine are quaternized with trimethylamine to form high-density quaternary ammonium salt active centers. These active centers are protected by the outer barrier, which reduces the degradation rate. As a result, the resin exhibits a significant decrease in the exchange capacity of strong groups after thermal degradation. Under long-term high-temperature wastewater treatment conditions, it has both high exchange capacity and long-term thermal stability. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The commercially available linear polyethyleneimine used in this invention was purchased from Zhejiang Zhenghe Silicon Materials Co., Ltd., and its grade is 207-35.

[0032] The branched polyethyleneimine used in this invention was purchased from Shanghai Hanluo New Materials Co., Ltd., with a molecular weight of 30,000, model number HM-2000, and a density of 1.04 kg / m³. 3 ;

[0033] The hydroxyl-terminated polyethersulfone used in this invention was purchased from Dongguan Dongli Plastic Raw Materials Co., Ltd., with item number hh96894625 and molecular weight of 8000-15000.

[0034] The gelatin used in this invention was purchased from Guangdong Mingcheng Biotechnology Co., Ltd., with a particle size of 120 mesh and a viscosity of 3.0-5 mPa·s;

[0035] The paraformaldehyde used in this invention was purchased from Wuhan Jiyesheng Chemical Co., Ltd., with an effective formaldehyde content of ≥91% and a low molecular weight white powder granule appearance.

[0036] The mesoporous silica nanospheres used in this invention were purchased from Beijing Zhongke Keyou Technology Co., Ltd., with a surface pore size of 2-3 nm and a particle size of 100-400 nm.

[0037] Example 1

[0038] This embodiment provides a method for preparing epoxy-modified silicon spheres, including the following steps:

[0039] Weigh 50g of mesoporous silica nanospheres, 1000mL of ethanol and 50mL of deionized water and place them in a reaction vessel under nitrogen atmosphere and stir. Add 20g of 3-glycidyl etheroxypropyltrimethoxysilane and stir at room temperature for 3min. Add 3wt% acetic acid aqueous solution to adjust the pH to 5.5. Heat the reaction vessel to 35℃ and keep it at that temperature for 2h. After the reaction is completed, let the reaction system cool to room temperature, filter it, wash the filter cake once with ethanol and once with deionized water, and transfer it to a vacuum drying oven at 55℃ to dry for 20h to obtain epoxy-modified silica nanospheres.

[0040] The silanol groups on the surface of mesoporous silica undergo a hydrolysis-condensation reaction with 3-glycidoxypropyltrimethoxysilane in a weakly acidic ethanol and water system. The silane methoxy group hydrolyzes to generate silanol, which dehydrates and condenses with the hydroxyl groups on the silica surface to form Si-O-Si covalent bonds, thereby achieving chemical grafting of epoxy groups on the outer surface of mesoporous silica and obtaining epoxy-modified silica spheres.

[0041] The silanol groups on the surface of mesoporous silica and the silane coupling agent undergo hydrolysis and dehydration condensation reactions to specifically modify the epoxy groups on the outer surface of the inorganic carrier with stable Si-O-Si covalent bonds. While ensuring the long-term hydrothermal stability of the composite microspheres, a highly active interfacial reaction network is introduced, providing a key bridge for the covalent anchoring of the subsequent organic engineering plastic layer and improving the high-temperature resistance and overall skeleton strength of the ion exchange resin.

[0042] Example 2

[0043] This embodiment provides a method for preparing epoxy-modified silicon spheres, including the following steps:

[0044] Weigh 100g of mesoporous silica nanospheres, 2000mL of ethanol and 100mL of deionized water and place them in a reaction vessel under nitrogen atmosphere and stir. Add 40g of 3-glycidyl etheroxypropyltrimethoxysilane and stir at room temperature for 4min. Add 4wt% acetic acid aqueous solution to adjust the pH to 6.0. Heat the reaction vessel to 40℃ and keep it at that temperature for 3h. After the reaction is completed, let the reaction system cool to room temperature, filter it, wash the filter cake twice with ethanol and deionized water in turn, and transfer it to a vacuum drying oven at 60℃ to dry for 22h to obtain epoxy-modified silica nanospheres.

[0045] Example 3

[0046] This embodiment provides a method for preparing epoxy-modified silicon spheres, including the following steps:

[0047] Weigh 150g of mesoporous silica nanospheres, 3000mL of ethanol and 150mL of deionized water and place them in a reaction vessel under nitrogen atmosphere and stir. Add 60g of 3-glycidyl etheroxypropyltrimethoxysilane and stir at room temperature for 5min. Add 5wt% acetic acid aqueous solution to adjust the pH to 6.5. Heat the reaction vessel to 45℃ and keep it at this temperature for 4h. After the reaction is completed, let the reaction system cool to room temperature, filter it, wash the filter cake with ethanol and deionized water four times in sequence, and transfer it to a vacuum drying oven at 65℃ to dry for 24h to obtain epoxy-modified silica nanospheres.

[0048] Example 4

[0049] This embodiment provides a method for preparing macroporous chloromethylated polystyrene, including the following steps:

[0050] Step ①: Preparation of ternary copolymer mixed monomer oil phase

[0051] Weigh out 800g of styrene, 50g of N-vinylcarbazole, 50g of divinylbenzene, 350mL of toluene, 300mL of n-heptane, and 5g of benzoyl peroxide and place them in a reaction vessel. Stir until homogeneous to obtain a ternary copolymer mixed monomer oil phase.

[0052] Step 2: Preparation of macroporous chloromethylated polystyrene microspheres

[0053] Weigh out 3000 mL of deionized water, 20 g of polyvinyl alcohol, 10 g of gelatin, and 80 g of sodium chloride and place them in a nitrogen-protected reactor. Stir the reactor and heat it to 55°C. Keep stirring for 0.5 h. Add 800 g of the ternary copolymer mixed monomer oil phase. Heat the reactor to 75°C and keep reacting for 2 h. Heat the reactor to 85°C and keep reacting for 6 h. After the reaction is complete, let the reaction system cool to room temperature, filter it, wash the filter cake twice with deionized water and ethanol, and transfer it to an oven at 50°C to dry for 20 h to obtain macroporous chloromethylated polystyrene microspheres.

[0054] Step ③: Preparation of macroporous chloromethylated polystyrene

[0055] Weigh 80g of macroporous chloromethylated polystyrene microspheres and 500mL of 1,2-dichloroethane and place them in a reaction vessel. Stir for 4 hours, then add 50g of paraformaldehyde and 30g of anhydrous zinc chloride. Keep the reaction vessel in an ice bath at 0°C and slowly add 100mL of thionyl chloride at a dropping rate of 10mL / h, controlling the addition to be completed within 1 hour. After the addition is complete, remove the ice bath and slowly heat the reaction vessel to 40°C. Maintain the temperature for 10 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, then slowly pour the reaction solution into 5000mL of ice water to quench the residual thionyl chloride. Collect the microspheres by suction filtration. Wash the filter cake once with 5% hydrochloric acid aqueous solution, deionized water, and anhydrous ethanol until the washing solution is neutral. Transfer the filter cake to a vacuum drying oven at 50°C and dry for 20 hours to obtain macroporous chloromethylated polystyrene.

[0056] Styrene, N-vinylcarbazole, and divinylbenzene were subjected to free radical copolymerization in an aqueous suspension system containing polyvinyl alcohol and gelatin under the initiation of benzoyl peroxide. Sodium chloride stabilized the droplet dispersion. Toluene and n-heptane were used as mixed porogens to form phase separation during the polymerization process. After polymerization, the porogens were removed by washing and extraction, leaving a through-pore macroporous structure to obtain macroporous polystyrene microspheres. After the macroporous chloromethylated polystyrene microspheres were fully swollen in 1,2-dichloroethane, paraformaldehyde and thionyl chloride were reacted in situ under the catalysis of anhydrous zinc chloride to generate chloromethylated active species, which underwent electrophilic substitution reaction on the aromatic rings of polystyrene and N-vinylcarbazole, introducing benzyl chloride groups to obtain macroporous chloromethylated polystyrene.

[0057] By introducing a carbazole heterocyclic structure with excellent thermal stability, the high-temperature creep resistance of the resin skeleton is significantly improved. Combined with a mixed porogen, a continuous macroporous network is constructed to ensure high flow rate mass transfer efficiency in the wastewater treatment process. Subsequent in-situ chloromethylation modification introduces active functional groups at a high density throughout the resin without destroying the macroporous network and rigid skeleton. This provides an anchoring network for subsequent covalent encapsulation of the outer layer and lays a high-density functional site foundation for the construction of the final large-capacity quaternary ammonium active center.

[0058] Example 5

[0059] This embodiment provides a method for preparing macroporous chloromethylated polystyrene, including the following steps:

[0060] Step ①: Preparation of ternary copolymer mixed monomer oil phase

[0061] Weigh out 900g of styrene, 100g of N-vinylcarbazole, 100g of divinylbenzene, 550mL of toluene, 450mL of n-heptane, and 15g of benzoyl peroxide and place them in a reaction vessel. Stir until homogeneous to obtain a ternary copolymer mixed monomer oil phase.

[0062] Step 2: Preparation of macroporous chloromethylated polystyrene microspheres

[0063] Weigh out 4000 mL of deionized water, 30 g of polyvinyl alcohol, 15 g of gelatin, and 110 g of sodium chloride and place them in a nitrogen-protected reactor. Stir the reactor and heat it to 60°C. Keep stirring for 1 hour. Add 1000 g of the ternary copolymer mixed monomer oil phase. Heat the reactor to 80°C and keep reacting for 2.5 hours. Heat the reactor to 90°C and keep reacting for 7 hours. After the reaction is complete, let the reaction system cool to room temperature, filter it, and wash the filter cake three times with deionized water and ethanol. Transfer it to an oven at 55°C and dry for 22 hours to obtain macroporous chloromethylated polystyrene microspheres.

[0064] Step ③: Preparation of macroporous chloromethylated polystyrene

[0065] Weigh 90g of macroporous chloromethylated polystyrene microspheres and 750mL of 1,2-dichloroethane and place them in a reaction vessel. Stir for 5 hours. Add 100g of paraformaldehyde and 55g of anhydrous zinc chloride. Keep the reaction vessel in an ice bath at 3°C. Slowly add 150mL of thionyl chloride at a dropping rate of 15mL / h, controlling the addition to be completed in 1.2 hours. After the addition is complete, remove the ice bath and slowly heat the reaction vessel to 45°C. Maintain the temperature for 11 hours. After the reaction is completed, wait for the reaction system to cool to room temperature. Slowly pour the reaction solution into 5000mL of ice water to quench the residual thionyl chloride. Collect the microspheres by suction filtration. Wash the filter cake twice with 5% hydrochloric acid aqueous solution, deionized water, and anhydrous ethanol, until the washing solution is neutral. Transfer to a vacuum drying oven at 55°C and dry for 22 hours to obtain macroporous chloromethylated polystyrene.

[0066] Example 6

[0067] This embodiment provides a method for preparing macroporous chloromethylated polystyrene, including the following steps:

[0068] Step ①: Preparation of ternary copolymer mixed monomer oil phase

[0069] Weigh out 1000g of styrene, 150g of N-vinylcarbazole, 150g of divinylbenzene, 700mL of toluene, 600mL of n-heptane, and 20g of benzoyl peroxide and place them in a reaction vessel. Stir until homogeneous to obtain a ternary copolymer mixed monomer oil phase.

[0070] Step 2: Preparation of macroporous chloromethylated polystyrene microspheres

[0071] Weigh out 5000 mL of deionized water, 40 g of polyvinyl alcohol, 20 g of gelatin, and 150 g of sodium chloride and place them in a nitrogen-protected reactor. Stir the reactor and heat it to 65°C. Keep stirring for 1 hour. Add 1200 g of the ternary copolymer mixed monomer oil phase. Heat the reactor to 85°C and keep reacting for 3 hours. Heat the reactor to 95°C and keep reacting for 8 hours. After the reaction is complete, let the reaction system cool to room temperature, filter it, and wash the filter cake four times with deionized water and ethanol. Transfer it to an oven at 60°C and dry for 24 hours to obtain macroporous chloromethylated polystyrene microspheres.

[0072] Step ③: Preparation of macroporous chloromethylated polystyrene

[0073] Weigh 100g of macroporous chloromethylated polystyrene microspheres and 1000mL of 1,2-dichloroethane and place them in a reaction vessel. Stir for 6 hours. Add 150g of paraformaldehyde and 80g of anhydrous zinc chloride. Keep the reaction vessel in an ice bath at 5°C. Slowly add 200mL of thionyl chloride at a dropping rate of 20mL / h, controlling the addition to be completed in 1.5 hours. After the addition is complete, remove the ice bath and slowly heat the reaction vessel to 45°C. Maintain the temperature for 12 hours. After the reaction is completed, wait for the reaction system to cool to room temperature. Slowly pour the reaction solution into 5000mL of ice water to quench the residual thionyl chloride. Collect the microspheres by suction filtration. Wash the filter cake three times in sequence with 5% hydrochloric acid aqueous solution, deionized water, and anhydrous ethanol until the washing solution is neutral. Transfer to a vacuum drying oven at 60°C and dry for 24 hours to obtain macroporous chloromethylated polystyrene.

[0074] Example 7

[0075] This embodiment provides a method for preparing a high-temperature resistant ion exchange resin for wastewater treatment, comprising the following steps:

[0076] Step (1): Preparation of macroporous hybrid microspheres

[0077] Weigh 200g of macroporous chloromethylated polystyrene prepared in Example 4 and 3000mL of N,N-dimethylformamide and place them in a reaction vessel under nitrogen atmosphere protection. Stir at room temperature for 2h, add 20g of branched polyethyleneimine, heat the reaction vessel to 60℃ and keep it at that temperature for 6h, add epoxy-modified silicon spheres prepared in Example 1 at 0.3 times the total molar amount of amino groups of branched polyethyleneimine, heat the reaction vessel to 80℃ and keep it at that temperature for 12h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, wash the filter cake twice with deionized water and ethanol, transfer it to a vacuum drying oven at 60℃ and dry for 10h to obtain macroporous hybrid microspheres.

[0078] Step 2: Preparation of macroporous hybrid polyethersulfone microspheres

[0079] Weigh out 200g of macroporous hybrid microspheres, 30g of hydroxyl-terminated polyethersulfone, 2000mL of N-methylpyrrolidone, 5g of p-toluenesulfonyl chloride, and 5g of potassium carbonate and place them in a reaction vessel. Stir the vessel and heat it to 80℃. Keep the temperature for 18h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and wash the filter cake once with deionized water and ethanol at 40℃. Transfer it to a vacuum drying oven at 70℃ and vacuum dry for 20h to obtain macroporous hybrid polyethersulfone microspheres.

[0080] Step 3: Preparation of anion exchange resin

[0081] Weigh 300g of macroporous hybrid polyethersulfone microspheres and 2000mL of ethanol and place them in a sealed reactor. Stir at room temperature for 1h, add 1000mL of 30wt% trimethylamine aqueous solution, heat the reactor to 40℃ and keep it at that temperature for 12h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, wash the filter cake once with deionized water, immerse the washed resin in 1mol / L sodium hydroxide solution for 2h, wash it with deionized water until neutral, transfer it to a vacuum drying oven at 45℃ and vacuum dry for 20h to obtain anion exchange resin.

[0082] Macroporous chloromethylated polystyrene microspheres utilize the size exclusion effect of branched polyethyleneimine to covalently bond with benzyl chloride on the outer surface and shallow surface of the microspheres. While preserving the deep benzyl chloride, exogenous free amine groups are introduced onto the surface of the microspheres. Subsequently, these amine groups undergo ring-opening addition reactions with the epoxy groups of epoxy-modified silicon spheres, achieving covalent anchoring of the inorganic silicon spheres. Furthermore, in a potassium carbonate deacidifying agent system, terminal hydroxyl polyethersulfone is activated by p-toluenesulfonyl chloride and undergoes nucleophilic substitution coupling with the residual amine groups of polyethyleneimine on the outer surface of the microspheres, forming a covalent coating layer on the microsphere shell. Small molecule trimethylamine deeply penetrates the swelling network and undergoes a quaternization reaction with the well-preserved deep skeleton benzyl chloride to construct quaternary ammonium salt active centers. After alkaline transformation, a macroporous hybrid polyethersulfone strongly basic anion exchange resin is obtained.

[0083] By utilizing the size exclusion effect of macromolecules to modify the surface of microspheres with polyethyleneimine, the aim is to introduce high-density exogenous amine groups while protecting deep exchange sites from consumption through steric hindrance. The ring-opening anchoring of epoxy-modified silicon spheres and the interfacial selective coupling of hydroxyl-terminated polyethersulfones construct an inorganic rigid framework and a thermally stable encapsulating shell on the outer layer of the resin, respectively. This synergistically endows the resin with high mechanical strength and heat creep resistance in high-temperature wastewater environments. Finally, the deep penetration quaternization and alkaline transformation of small molecule trimethylamine ensures the complete transformation of the deep high-activity sites of the microspheres into strongly basic functional centers, enabling the final resin to have both ultra-high exchange capacity and long-term thermal stability under harsh thermal conditions.

[0084] Example 8

[0085] This embodiment provides a method for preparing a high-temperature resistant ion exchange resin for wastewater treatment, comprising the following steps:

[0086] Step (1): Preparation of macroporous hybrid microspheres

[0087] Weigh 300g of macroporous chloromethylated polystyrene prepared in Example 5 and 4000mL of N,N-dimethylformamide and place them in a reaction vessel under nitrogen atmosphere protection. Stir at room temperature for 3h, add 30g of branched polyethyleneimine, heat the reaction vessel to 68℃ and keep it at that temperature for 7h, add epoxy-modified silicon spheres prepared in Example 2 at 0.3 times the total molar amount of amino groups of branched polyethyleneimine, heat the reaction vessel to 85℃ and keep it at that temperature for 14h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, wash the filter cake three times with deionized water and ethanol, transfer it to a vacuum drying oven at 65℃ and dry for 11h to obtain macroporous hybrid microspheres.

[0088] Step 2: Preparation of macroporous hybrid polyethersulfone microspheres

[0089] Weigh out 300g of macroporous hybrid microspheres, 50g of hydroxyl-terminated polyethersulfone, 3000mL of N-methylpyrrolidone, 7.5g of p-toluenesulfonyl chloride, and 7.5g of potassium carbonate and place them in a reaction vessel. Stir the mixture and heat the reaction vessel to 90℃. Maintain the temperature for 21h. After the reaction is complete, allow the reaction system to cool to room temperature and filter. Wash the filter cake twice with deionized water and ethanol at 45℃, and transfer it to a vacuum drying oven at 75℃. Dry the cake under vacuum for 22h to obtain macroporous hybrid polyethersulfone microspheres.

[0090] Step 3: Preparation of anion exchange resin

[0091] Weigh 350g of macroporous hybrid polyethersulfone microspheres and 2500mL of ethanol and place them in a sealed reactor. Stir at room temperature for 1.5h, add 1250mL of 35wt% trimethylamine aqueous solution, heat the reactor to 45℃ and keep it at that temperature for 14h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, wash the filter cake twice with deionized water, immerse the washed resin in 1mol / L sodium hydroxide solution for 3h, wash it with deionized water until neutral, transfer it to a vacuum drying oven at 50℃ and vacuum dry for 22h to obtain anion exchange resin.

[0092] Example 9

[0093] This embodiment provides a method for preparing a high-temperature resistant ion exchange resin for wastewater treatment, comprising the following steps:

[0094] Step (1): Preparation of macroporous hybrid microspheres

[0095] Weigh 400g of macroporous chloromethylated polystyrene prepared in Example 6 and 5000mL of N,N-dimethylformamide and place them in a reaction vessel under nitrogen atmosphere protection. Stir at room temperature for 4h, add 40g of branched polyethyleneimine, heat the reaction vessel to 75℃ and keep it at that temperature for 8h, add epoxy-modified silicon spheres prepared in Example 3 at 0.3 times the total molar amount of amino groups of branched polyethyleneimine, heat the reaction vessel to 90℃ and keep it at that temperature for 16h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, wash the filter cake 4 times with deionized water and ethanol, transfer it to a vacuum drying oven at 70℃ and dry for 12h to obtain macroporous hybrid microspheres.

[0096] Step 2: Preparation of macroporous hybrid polyethersulfone microspheres

[0097] Weigh out 400g of macroporous hybrid microspheres, 80g of hydroxyl-terminated polyethersulfone, 4000mL of N-methylpyrrolidone, 10g of p-toluenesulfonyl chloride, and 10g of potassium carbonate and place them in a reaction vessel. Stir the vessel and heat it to 100℃. Keep the temperature for 24h. After the reaction is complete, let the reaction system cool to room temperature, filter it, and wash the filter cake three times with deionized water and ethanol at 50℃. Transfer it to a vacuum drying oven at 80℃ and dry it under vacuum for 24h to obtain macroporous hybrid polyethersulfone microspheres.

[0098] Step 3: Preparation of anion exchange resin

[0099] Weigh 400g of macroporous hybrid polyethersulfone microspheres and 3000mL of ethanol and place them in a sealed reactor. Stir at room temperature for 2 hours. Add 1500mL of 40wt% trimethylamine aqueous solution. Heat the reactor to 50℃ and maintain the temperature for 18 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and wash the filter cake three times with deionized water. Immerse the washed resin in 1mol / L sodium hydroxide solution for 4 hours, then wash with deionized water until neutral. Transfer to a vacuum drying oven at 55℃ and vacuum dry for 24 hours to obtain anion exchange resin.

[0100] Comparative Example 1

[0101] The difference between this comparative example and Example 9 is that, in step (1) when preparing macroporous hybrid microspheres, the epoxy-modified silicon spheres are not used.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 9 is that, in step (2) when preparing macroporous hybrid polyethersulfone microspheres, the use of terminal hydroxyl polyethersulfone is omitted.

[0104] Comparative Example 3

[0105] The difference between this comparative example and Example 9 is that, in step (1) when preparing macroporous hybrid microspheres, commercially available linear polyethyleneimine is used in an equal amount to replace branched polyethyleneimine.

[0106] Performance testing:

[0107] Heat resistance and strong group exchange capacity: The heat resistance and strong group exchange capacity of the anion exchange resins prepared in Examples 7-9 and Comparative Examples 1-3 were tested according to the standard DL / T 953-2018 "Determination of Heat Resistance and Antioxidant Properties of Strong Basic Anion Exchange Resins for Water Treatment". The heat resistance test conditions were 90℃×48h. The decrease rate of strong group exchange capacity (quaternary ammonium salt groups) after thermal degradation was used for characterization. The strong group exchange capacity (quaternary ammonium salt groups) of the original resin sample was measured simultaneously.

[0108] Crushing strength: The crushing strength of the anion exchange resins prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard DL / T 519-2014 "Acceptance Standard for Ion Exchange Resins for Water Treatment in Power Plants". The test conditions were as follows: 20 resin particles were taken and the crushing strength of a single particle was measured at a falling speed of 0.1 cm / s. The average value was taken.

[0109] Sphericality after grinding: The sphericality after grinding of the anion exchange resins prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 12598-2023 "Determination of sphericality after grinding and sphericality of plastic ion exchange resins". The test conditions were 125 r / min rotation speed, 30 min grinding, and 0.315 mm sieve aperture.

[0110] Thermal decomposition temperature: The thermal decomposition temperature of the anion exchange resins prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 27761-2011 "Test Method for Weight Loss and Residual Amount of Thermogravimetric Analyzer". The test conditions were nitrogen atmosphere, heating rate of 10℃ / min, and 5% weight loss temperature was recorded. The specific data are shown in Table 1.

[0111] Table 1 - Performance Test Data for Each Sample

[0112]

[0113] Data Analysis:

[0114] The anion exchange resin prepared in this invention has a strong group exchange capacity of 1.38 mmol·g. -1 The thermal degradation showed a 6.8% decrease in the exchange capacity of strong groups, a crushing strength of 15.9 N / particle, and a sphericity of 94.8% after grinding, while the thermal decomposition temperature reached as high as 298℃. All of these data were superior to the comparative example.

[0115] This invention uses macroporous chloromethylated polystyrene as a framework, and selectively grafts branched polyethyleneimine onto the surface and shallow layer of microspheres using the size exclusion effect of the large molecular size, while retaining the deep benzyl chloride. Subsequently, through the ring-opening anchoring of epoxy-modified silicon spheres and interfacial coupling with hydroxyl-terminated polyethersulfone, an inorganic rigid framework and a heat-resistant coating shell are constructed on the outer layer of the resin. Finally, through trimethylamine quaternization and alkaline transformation, the high-temperature resistance and exchange capacity of the ion exchange resin are improved.

[0116] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-temperature resistant ion exchange resin for wastewater treatment, characterized in that, Includes the following steps: S1. Macroporous chloromethylated polystyrene and N,N-dimethylformamide are placed in a reaction vessel under nitrogen atmosphere protection and stirred at room temperature for 2-4 hours. Branched polyethyleneimine is added, the reaction vessel is heated to 60-75℃, and the reaction is maintained for 6-8 hours. Epoxy-modified silicon spheres are added, the reaction vessel is heated to 80-90℃, and the reaction is maintained for 12-16 hours. Post-treatment yields macroporous hybrid microspheres. S2. Place macroporous hybrid microspheres, hydroxyl-terminated polyethersulfone, N-methylpyrrolidone, p-toluenesulfonyl chloride and potassium carbonate in a reaction vessel and stir. Heat the reaction vessel to 80-100℃ and keep it at that temperature for 18-24 hours. After post-treatment, macroporous hybrid polyethersulfone microspheres are obtained. S3. Place macroporous hybrid polyethersulfone microspheres and ethanol in a sealed reactor and stir at room temperature for 1-2 hours. Add trimethylamine aqueous solution, heat the reactor to 40-50℃, and keep the reaction at this temperature for 12-18 hours. Post-treatment yields anion exchange resin.

2. The method for preparing a high-temperature resistant ion exchange resin for wastewater treatment according to claim 1, characterized in that, In step S1, the ratio of macroporous chloromethylated polystyrene, N,N-dimethylformamide, and branched polyethyleneimine is 20-40g:300-500mL:2-4g, and the molar amount of epoxy-modified silicon spheres is 0.3 times the total molar amount of amino groups in branched polyethyleneimine. In step S2, the ratio of macroporous hybrid microspheres, hydroxyl-terminated polyethersulfone, N-methylpyrrolidone, p-toluenesulfonyl chloride, and potassium carbonate is 20-40g:3-8g:200-400mL:0.5-1g:0.5-1g. In step S3, the ratio of macroporous hybrid polyethersulfone microspheres, ethanol, and trimethylamine aqueous solution is 30-40g:200-300mL:100-150mL, the concentration of trimethylamine aqueous solution is 30-40wt%, and the pressure inside the sealed reactor is maintained at 0.1-0.3MPa.

3. The method for preparing a high-temperature resistant ion exchange resin for wastewater treatment according to claim 1, characterized in that, The macroporous chloromethylated polystyrene was prepared by the following steps: A1. Styrene, N-vinylcarbazole, divinylbenzene, toluene, n-heptane and benzoyl peroxide are placed in a reaction vessel and stirred evenly to obtain a ternary copolymer mixed monomer oil phase; A2. Deionized water, polyvinyl alcohol, gelatin and sodium chloride are placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel is heated to 55-65℃ and stirred for 0.5-1h. Then, the ternary copolymer mixed monomer oil phase is added. The reaction vessel is heated to 75-85℃ and reacted for 2-3h. The reaction vessel is then heated to 85-95℃ and reacted for 6-8h. After post-treatment, macroporous chloromethylated polystyrene microspheres are obtained. A3. Place macroporous chloromethylated polystyrene microspheres and 1,2-dichloroethane in a reaction vessel and stir for 4-6 hours. Add paraformaldehyde and anhydrous zinc chloride. Keep the reaction vessel in an ice bath at 0-5°C. Slowly add thionyl chloride, controlling the addition to be completed in 1-1.5 hours. After the addition is complete, remove the ice bath and slowly heat the reaction vessel to 40-45°C. Maintain the temperature for 10-12 hours. Post-process to obtain macroporous chloromethylated polystyrene.

4. The method for preparing a high-temperature resistant ion exchange resin for wastewater treatment according to claim 3, characterized in that, In step A1, the ratio of styrene, N-vinylcarbazole, divinylbenzene, toluene, n-heptane, and benzoyl peroxide is 80-100g:5-15g:5-15g:35-70mL:30-60mL:0.5-2g; in step A2, the ratio of deionized water, polyvinyl alcohol, gelatin, sodium chloride, and the ternary copolymer mixed monomer oil phase is 300-500mL:2-4g:1-2g:8-15g:80-120g; in step A3, the ratio of macroporous chloromethylated polystyrene microspheres, 1,2-dichloroethane, paraformaldehyde, anhydrous zinc chloride, and thionyl chloride is 8-10g:50-100mL:5-15g:3-8g:10-20mL, and the dropping rate of thionyl chloride is controlled at 10-20mL / h.

5. The method for preparing a high-temperature resistant ion exchange resin for wastewater treatment according to claim 1, characterized in that, The preparation method of the epoxy-modified silica spheres is as follows: mesoporous silica nanospheres, ethanol and deionized water are placed in a reaction vessel under nitrogen atmosphere and stirred. 3-glycidyl etheroxypropyltrimethoxysilane is added and stirred at room temperature for 3-5 min. An aqueous acetic acid solution is added to adjust the pH to 5.5-6.

5. The reaction vessel is heated to 35-45℃ and kept at this temperature for 2-4 h. The epoxy-modified silica spheres are then obtained after post-treatment.

6. The method for preparing a high-temperature resistant ion exchange resin for wastewater treatment according to claim 5, characterized in that, The ratio of the mesoporous silica nanospheres, ethanol, deionized water and 3-glycidoxypropyltrimethoxysilane is 5-15g:100-300mL:5-15mL:2-6g, and the concentration of the acetic acid aqueous solution is 3-5wt%.

7. A high-temperature resistant ion exchange resin for wastewater treatment, characterized in that, The high-temperature resistant ion exchange resin for wastewater treatment is prepared using the method described in any one of claims 1-6.

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