Magnetic ion exchange resin and preparation method thereof

Abstract

The invention discloses a magnetic ion exchange resin and a preparation method thereof, and the preparation method comprises the following steps: preparing a reaction solution which comprises magnetic particles, glycidyl methacrylate, divinylbenzene and a photoinitiator; the mass ratio of the glycidyl methacrylate to the divinyl benzene is (4.5-10): 1; an ultraviolet-initiated polymerization step: irradiating the reaction solution by ultraviolet light to initiate a polymerization reaction to obtain magnetic microspheres; a functional modification step: mixing the magnetic microspheres with an ammoniation reagent for ammoniation reaction to prepare ammoniated magnetic microspheres; and mixing the ammoniated magnetic microspheres with an alkylation reagent, and carrying out an alkylation reaction to prepare the magnetic ion exchange resin. According to the method, the production time is remarkably shortened, the extra energy consumption is reduced, and the process production flow is effectively simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a magnetic ion exchange resin and a preparation method thereof. Background Art

[0002] Magnetic ion exchange resin is a composite material that combines magnetic nanoparticles (for example, Fe2O3 and Fe3O4) with an organic resin skeleton, and has both efficient adsorption and magnetic response properties. It selectively adsorbs heavy metals (for example, lead, cadmium) and various pollutants in water through functional groups, and uses an external magnetic field to achieve rapid solid-liquid separation, avoiding the tedious problem of traditional resin regeneration. In water treatment, this material can significantly improve the efficiency of pollutant removal, reduce energy consumption and the risk of secondary pollution, and is particularly suitable for deep treatment of industrial wastewater and purification of high-salinity water bodies. As environmental protection standards become stricter, it has broad application prospects in heavy metal recovery, micro-pollution control, and circulating water systems, and is an important development direction of green water treatment technology.

[0003] Currently, the synthesis methods of magnetic ion exchange resins are all suspension polymerization thermal initiation technology, which uses heat energy and initiators to drive the copolymerization reaction of magnetic particles and reactive monomers (thermal initiation copolymerization). However, this method has the following significant drawbacks:

[0004] (1) Low reaction efficiency: The thermally initiated copolymerization reaction takes as long as 5 to 10 hours, and the temperature needs to be raised in stages to control the polymerization process. The long cycle restricts the efficiency of industrial production.

[0005] (2) Problem of excessive initiator and dispersant: The thermal initiation process requires the addition of excessive initiator (e.g., benzoyl peroxide) and dispersant (e.g., gelatin) to maintain reaction stability. This not only increases the cost of raw materials, but also requires repeated extraction of residues with organic solvents (e.g., anhydrous ethanol) after polymerization, which complicates the production process.

[0006] (3) Additional energy dependence: In addition to thermal energy input, the thermal initiation process needs to rely on ultrasound to provide additional energy to promote the decomposition of initiators or the activation of reaction monomers, resulting in a significant increase in energy consumption.

[0007] Therefore, an efficient and low-consumption synthesis method is urgently needed to break through the existing technical bottleneck and promote the industrial application of magnetic ion exchange resins.

[0008] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing magnetic ion exchange resin using ultraviolet-induced polymerization technology, which can significantly shorten the production time, reduce additional energy consumption, and effectively simplify the process production flow.

[0010] In order to achieve the above object, the present invention provides a method for preparing a magnetic ion exchange resin, comprising:

[0011] A reaction solution is prepared, wherein the reaction solution comprises: magnetic particles, glycidyl methacrylate, divinylbenzene, and a photoinitiator; the mass ratio of the glycidyl methacrylate to the divinylbenzene is (4.5-10):1;

[0012] UV-induced polymerization step: irradiating the reaction solution with UV light to initiate a polymerization reaction to obtain magnetic microspheres;

[0013] Functional modification step: mixing the magnetic microspheres with an amination reagent to carry out an amination reaction to prepare ammoniated magnetic microspheres; mixing the ammoniated magnetic microspheres with an alkylation reagent to carry out an alkylation reaction to prepare a magnetic ion exchange resin.

[0014] Optionally, the power of the ultraviolet light is 10W to 50W, and the wavelength is 200nm to 300nm.

[0015] Optionally, the photoinitiator comprises at least any one of 2-hydroxy-2-methylpropiophenone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0016] Optionally, the mass ratio of the photoinitiator to the total mass of the glycidyl methacrylate and the divinylbenzene is 1:(80-200).

[0017] Optionally, the reaction solution further comprises: a porogen, the porogen comprising any one or more of cyclohexanol, n-hexane, n-heptane, n-octane, and toluene; and the mass ratio of the porogen to the total mass of the glycidyl methacrylate and the divinylbenzene is (0.5-1):1.

[0018] Optionally, the reaction solution further comprises: a dispersant, wherein the dispersant comprises any one or more of polyvinyl alcohol, sodium chloride, gelatin, and dodecanol; and the mass percentage of the dispersant in the reaction solution is 1% to 8%.

[0019] Optionally, the magnetic particles contain at least one of ferric oxide modified with oleic acid and ferrosoferric oxide modified with a silane coupling agent.

[0020] Optionally, in the functional modification step, the amination reagent comprises any one of trimethylamine hydrochloride and trimethylamine hydroxide.

[0021] Optionally, in the functionalization modification step, the alkylating agent comprises 1,2-dichloroethane.

[0022] The present invention also provides a magnetic ion exchange resin, which is prepared by the above-mentioned preparation method of the magnetic ion exchange resin.

[0023] Compared with the prior art, the beneficial effects of the technical solution of the present invention include at least:

[0024] The present invention successfully prepares a magnetic ion exchange resin using ultraviolet-induced polymerization technology, using glycidyl methacrylate as a reactive monomer, divinylbenzene as a crosslinker, and modified iron oxides (oleic acid-modified Fe2O3 or silane-coupling agent-modified Fe3O4) as magnetic particles. Compared to traditional thermal initiation, the present invention's ultraviolet-induced polymerization technology utilizes the rapid decomposition of active free radicals by the photoinitiator upon light absorption. This rapidly triggers a reaction between the reactive monomer, crosslinker, and magnetic particles, forming a uniform three-dimensional crosslinked network structure that encapsulates the magnetic particles. Compared with traditional thermal initiation, on the one hand, due to the higher efficiency of light-induced excitation polymerization, the ultraviolet-induced polymerization rate of the present invention (reaction time 1h to 3h) is significantly higher than the thermally-induced polymerization rate (reaction time 5h to 10h), which greatly improves the reaction efficiency, shortens the production time, and is conducive to industrial production; on the other hand, the method of the present invention does not require excessive initiators and dispersants to compensate for the premature decomposition or complete consumption of the initiators and dispersants caused by the long-term high-temperature reaction initiated by heat, thereby reducing raw material costs and reducing the cleaning process; on the other hand, the method of the present invention does not require additional ultrasonic energy or heat energy input to promote the polymerization reaction, which can significantly reduce energy consumption.

[0025] Furthermore, the present invention adopts low-pressure ultraviolet-induced polymerization. Since low-pressure ultraviolet-induced polymerization is carried out at room temperature and generates little heat during the polymerization process, it avoids the thermal decomposition of reactants (glycidyl methacrylate, divinylbenzene, etc.) caused by high temperature in thermal initiation technology, thereby ensuring that more active sites participate in the polymerization reaction, which is conducive to forming a more uniform three-dimensional cross-linked network and reducing diffusion resistance. On the one hand, it is conducive to providing a smooth diffusion path for the amination reagent and alkylation reagent in the subsequent functional modification step, increasing the grafting efficiency of the functional group (quaternary ammonium group), and forming a magnetic ion exchange resin containing more functional groups, thereby greatly improving the ion exchange capacity; on the other hand, it helps the diffusion of target anions inside the resin and increases the adsorption amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart of a method for preparing a magnetic ion exchange resin.

[0027] Figure 2 The present invention is another process flow chart of a method for preparing a magnetic ion exchange resin.

[0028] Figure 3Field emission scanning electron microscope (SEM) images and element distribution maps of MOA, MGD-OA, MMPS, and MGD-MPS prepared in Examples 1 and 2 of the present invention; wherein, (a) represents the SEM image of MOA; (b) represents the SEM image of MGD-OA; (c) represents an enlarged image of a pore in (b); (d) represents the SEM image of MMPS; (e) represents the SEM image of MGD-MPS; (f) represents an enlarged image of a pore in (e); (g) represents the element distribution map of C, O, N, and Fe of MGD-OA; (h) represents the element distribution map of C, O, N, and Fe of MGD-MPS.

[0029] Figure 4 These are the hysteresis loop diagrams of MGD-OA and MGD-MPS prepared in Examples 1 and 2 of the present invention.

[0030] Figure 5 Zeta potential diagrams of MOA, MGD-OA, MMPS, and MGD-MPS prepared in Examples 1 and 2 of the present invention.

[0031] Figure 6 These are the full XPS spectra of MOA, MGD-OA, MMPS, and MGD-MPS prepared in Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0032] The following is a further detailed description of a magnetic ion exchange resin and a preparation method thereof proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated in the drawings of this specification are only used to match the content disclosed in the specification, so that people familiar with this technology can understand and read them, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0033] The terms "magnetic ion exchange resin" and "magnetic resin" are used interchangeably herein. Magnetic resin refers to a composite resin material made by embedding magnetic particles into a conventional ion exchange matrix. The magnetic resin has both the ability to rapidly separate particles under an external magnetic field and the ion exchange capacity of conventional ion exchange resins. Taking a chlorine-type magnetic resin as an example, the surface of the magnetic resin has functional groups with chloride ions (e.g., [-N+ (CH3)3]Cl - , where Cl - is called a counterion), when containing other anions (e.g., CrO4 2- 、AsO4 3- ) flows through the magnetic resin, Cl - It will undergo a replacement reaction with these anions, causing the target anions to be adsorbed and combined with the magnetic resin, while releasing Cl - By applying an external magnetic field (such as a permanent magnet or electromagnet), the magnetic resin bound to the target anions is quickly attracted to the direction of the magnetic field and can be quickly separated from the solution without the need for traditional filtration or centrifugation, achieving efficient wastewater treatment.

[0034] The term "ion exchange capacity" as used herein refers to the milliequivalent number of ions that can be exchanged per gram of resin.

[0035] As described in the background technology, existing magnetic ion exchange resins have problems such as the need to add excessive initiators and dispersants, low reaction efficiency, and the need for ultrasonic energy input, which significantly increases process costs and leads to the complexity of process equipment and process flow, which is not conducive to the large-scale industrial production of magnetic ion exchange resins.

[0036] The inventors have discovered that ultraviolet (UV)-initiated polymerization technology has been applied to the synthesis and modification of polyacrylimide and natural polymer flocculants, achieving excellent results. UV initiation includes two forms: high-pressure UV initiation (500W-1000W mercury lamp) and low-pressure UV initiation (10W-50W mercury lamp). Compared with high-pressure UV initiation, low-pressure UV initiation releases less heat and does not require complex reflux condensation equipment, simplifying experimental and industrial production equipment. Compared with thermal initiation, low-pressure UV initiation has a significantly higher polymerization rate (reaction time of 1h-3h) than thermal initiation (reaction time of 5h-10h), significantly improving the efficiency of monomer-to-polymer conversion.

[0037] In view of this, and to address the above-mentioned problems, the present invention proposes for the first time a method for preparing a magnetic ion exchange resin. The method utilizes glycidyl methacrylate as a reactive monomer, divinylbenzene as a crosslinking agent, and modified iron oxide (oleic acid-modified Fe2O3 or silane coupling agent-modified Fe3O4) as magnetic particles, and utilizes ultraviolet-induced polymerization technology to prepare the magnetic ion exchange resin. The present invention's ultraviolet-induced polymerization technology, on the one hand, significantly increases the reaction rate, reducing the required synthesis time to less than 3 hours, significantly reducing the synthesis time required by traditional methods (5 to 10 hours), thus facilitating industrial production. On the other hand, it eliminates the need for excessive initiators and dispersants to maintain the stability of the reaction system, reducing raw material costs and the cleaning process, thus simplifying the process flow. Furthermore, it eliminates the need for additional ultrasonic energy or heat input to promote the polymerization reaction, significantly reducing energy consumption. Furthermore, the low-pressure UV-initiated polymerization adopted in the present invention can be carried out at room temperature, and little heat is generated during the polymerization process, avoiding the thermal decomposition of reactants caused by high temperature in thermal initiation technology, thereby ensuring that more active sites participate in the polymerization reaction, which is conducive to the formation of a more uniform three-dimensional cross-linked network, and further conducive to the formation of a magnetic ion exchange resin containing more functional groups (quaternary ammonium groups), thereby greatly improving the ion exchange capacity.

[0038] The following is a detailed description with reference to the accompanying drawings and embodiments.

[0039] like Figure 1 As shown, the present invention provides a method for preparing a magnetic ion exchange resin, comprising:

[0040] Step 1: preparing a reaction solution, wherein the reaction solution comprises: magnetic particles, glycidyl methacrylate, divinylbenzene, and a photoinitiator; the mass ratio of the glycidyl methacrylate to the divinylbenzene is (4.5-10):1.

[0041] In some embodiments, such as Figure 2 As shown, the step 1 includes:

[0042] Step 1.1, prepare magnetic particles.

[0043] In some embodiments, the magnetic particles are modified iron oxides. As an example, the magnetic particles are ferric oxide (Fe2O3) modified with oleic acid. The role of oleic acid modification is to adsorb and wrap the surface of Fe2O3, so that the hydrophobicity of the surface of Fe2O3 is improved, thereby improving the dispersibility of the magnetic particles in the magnetic resin. Specifically, the oleic acid structure contains carboxyl groups (-COOH), which can form chemical bonds with the surface of Fe2O3 through the carboxyl groups, so that it can be adsorbed and wrapped on the surface of Fe2O3. At the same time, the oleic acid has a long chain structure. After adsorption on the surface of Fe2O3, it can enhance the hydrophobicity of the surface of Fe2O3, thereby improving the dispersibility of the magnetic particles in the magnetic resin, and then effectively avoiding the agglomeration of Fe2O3 that may occur in the subsequent polymerization process, so that it is more evenly distributed in the magnetic resin.

[0044] The preparation method of oleic acid-modified ferric oxide comprises: adding Fe2O3, ammonia, oleic acid, and acetone to ultrapure water, mechanically stirring in a water bath at 60°C to 100°C for 30 minutes to 1 hour to produce a magnetic particle dispersion. Solid magnetic particles in the magnetic particle dispersion are separated by external magnet adsorption and washed with ultrapure water until the pH reaches neutral. The solid magnetic particles are then dried to produce oleic acid-modified Fe2O3.

[0045] As another example, the magnetic particles are ferroferric oxide (Fe3O4) modified with a silane coupling agent (KH570). KH570 can reduce the aggregation tendency of Fe3O4 through surface coating. Furthermore, after hydrolysis, KH570 possesses both silanol (Si-OH) groups that react with inorganic surfaces and unsaturated double bonds (acrylic groups) that react with organic matrices. This allows for the formation of a "molecular bridge" structure between the Fe3O4 surface and the resin matrix during the subsequent UV-induced polymerization step, significantly enhancing the inorganic-organic interface bonding strength and allowing the Fe3O4 to be better encapsulated within the resin.

[0046] The preparation method of KH570-modified Fe3O4 includes: using deionized water and anhydrous ethanol as solvents, adjusting the pH of the solvent to between 8.0 and 10.0 with ammonia, adding KH570, and hydrolyzing for 20 minutes to 1 hour to obtain KH570'. Fe3O4, ammonia, KH570', and acetone are added to ultrapure water, and mechanically stirred in a water bath at 60°C to 100°C for 30 minutes to 1 hour to react to obtain a mixed solution of magnetic particles. The solid magnetic particles in the mixed solution of magnetic particles are separated by adsorption using an external magnet, and washed with ultrapure water until the pH reaches neutral. The solid magnetic particles are dried to obtain KH570-modified Fe3O4.

[0047] Step 1.2, preparing an aqueous phase, wherein the aqueous phase consists of ultrapure water and a dispersant.

[0048] Step 1.3, preparing an oil phase, wherein the oil phase is composed of glycidyl methacrylate, divinylbenzene, magnetic particles, a photoinitiator, a porogen, and a dispersant.

[0049] Step 1.4, mixing the aqueous phase and the oil phase to obtain a reaction solution.

[0050] The photoinitiator, upon absorbing ultraviolet light, rapidly decomposes to produce active free radicals, which rapidly initiate the copolymerization of glycidyl methacrylate and divinylbenzene. The porogen promotes the formation of a pore structure within the magnetic resin, increasing its porosity. The dispersant improves the dispersibility of the reactants in the reaction solution, ensuring their uniform distribution, thereby facilitating the formation of a uniform three-dimensional cross-linked network within the resin.

[0051] The photoinitiator comprises at least one of 2-hydroxy-2-methylpropiophenone (Irgacure 1173) and 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the mass ratio of the photoinitiator to the total mass of the glycidyl methacrylate and the divinylbenzene is 1:(80-200). The mass ratio of the magnetic particles to the glycidyl methacrylate is 1:(8-10). The porogen comprises any one or more of cyclohexanol, n-hexane, n-heptane, n-octane, and toluene, and the mass ratio of the porogen to the total mass of the glycidyl methacrylate and the divinylbenzene is (0.5-1):1. The dispersant comprises any one or more of polyvinyl alcohol, sodium chloride, gelatin, and dodecanol, and the mass percentage of the dispersant in the reaction solution is 1% to 8%.

[0052] The present invention has found that by adopting UV-initiated polymerization technology, the required amount of dispersant and initiator added is effectively reduced. The reasons include:

[0053] (1) Ultraviolet photoinitiators absorb photon energy of a specific wavelength and directly decompose to produce active free radicals to initiate the polymerization reaction of the reactants. This photochemical reaction has a higher excitation efficiency. A small amount of photoinitiator can quickly generate enough active free radicals. Traditional thermal initiation requires continuous decomposition of thermal initiators through heat energy. Moreover, the utilization rate of thermal initiators may be reduced due to side reactions (such as uneven thermal decomposition and chain termination) at high temperatures, so an excess amount is required to maintain the reaction rate.

[0054] (2) The polymerization rate of UV-induced polymerization is relatively fast, and the polymerization reaction can be completed quickly (reaction time 1h~3h), thereby shortening the time the dispersant needs to work and reducing the risk of particle sedimentation and agglomeration. However, the thermal-induced reaction cycle is long (reaction time 5h~10h), so a higher amount of dispersant is required to maintain good dispersion of the reaction system for a long time.

[0055] (3) UV initiation can be carried out at room temperature, which makes the system viscosity lower and is not conducive to the aggregation of reactants. Traditional thermal initiation is carried out at high temperature, which will promote the thermal decomposition of reactants, initiators, etc., and increase the viscosity of the system. Therefore, a higher amount of dispersant is required to continuously inhibit particle aggregation.

[0056] Step 2, ultraviolet-induced polymerization step: initiating a polymerization reaction by irradiating the reaction solution with ultraviolet light to obtain magnetic microspheres.

[0057] The photoinitiator in the reaction solution decomposes after absorbing ultraviolet light to produce active free radicals. Under the action of the active free radicals, the acrylate double bonds of glycidyl methacrylate form polymer chains through chain growth reaction. Divinylbenzene acts as a cross-linking agent in the copolymerization reaction. The vinyl double bonds of divinylbenzene and the acrylate double bonds of glycidyl methacrylate are alternately connected during chain growth to form a three-dimensional network cross-linked structure. At the same time, the magnetic particles are uniformly dispersed in the three-dimensional cross-linked network through surface chemical bonding or physical encapsulation. For example, Fe3O4 modified with KH570 chemically bonds with the epoxy groups of glycidyl methacrylate through the acrylic groups on its surface, thereby being firmly anchored in the pores or interfaces of the cross-linked network.

[0058] In some embodiments, the ultraviolet light is low-pressure ultraviolet light, having a power of 10W to 50W and a wavelength of 200nm to 300nm. As an example, step 2 comprises: irradiating the mixture with low-pressure ultraviolet light for 2 to 3 hours under an inert gas atmosphere with a stirring speed of 400rpm to 600rpm, separating the magnetic microspheres, and washing the mixture alternately with ultrapure water and anhydrous ethanol to remove residual photoinitiator, dispersant, and porogen. After drying, the magnetic microspheres are obtained.

[0059] The low-pressure ultraviolet-induced polymerization technology used in the present invention includes at least the following functions:

[0060] (1) The polymerization rate of low-pressure UV initiation (reaction time 1h~3h) is significantly higher than that of thermal initiation (reaction time 5h~10h), which greatly improves the efficiency of conversion from reaction monomers to polymers and is conducive to industrial production.

[0061] (2) No excessive amount of initiator or dispersant is required to compensate for the premature decomposition or complete consumption of the initiator or dispersant caused by the long-term high-temperature reaction induced by heat, thereby reducing the cost of raw materials and the cleaning process, effectively simplifying the process flow.

[0062] (3) No additional ultrasonic energy or heat energy input is required to promote the polymerization reaction, which significantly reduces energy consumption.

[0063] (4) Low-pressure UV-initiated polymerization is carried out at room temperature, and little heat is generated during the polymerization process, which avoids the thermal decomposition of reactants caused by high temperature in thermal initiation technology, thereby ensuring that more active sites participate in the polymerization reaction, which is conducive to the formation of a more uniform three-dimensional cross-linked network and reduces diffusion resistance. On the one hand, it helps the diffusion of target anions inside the resin; on the other hand, it is conducive to the subsequent functional modification step to form more functional groups (quaternary ammonium groups) on the surface of the magnetic resin, so that the magnetic resin can adsorb and bind more target anions, greatly improving the ion exchange capacity of the magnetic resin.

[0064] Step 3: mixing the magnetic microspheres with an aminating agent to carry out an amination reaction to prepare ammoniated magnetic microspheres; and mixing the ammoniated magnetic microspheres with an alkylating agent to carry out an alkylation reaction to prepare a magnetic ion exchange resin.

[0065] Wherein, the aminating agent comprises any one of trimethylamine hydrochloride and trimethylamine hydroxide. The aminating agent uses its lone pair electrons to attack the epoxy group in glycidyl methacrylate to cause a ring-opening reaction, thereby obtaining ammoniated magnetic microspheres. As an example, the preparation method of the ammoniated magnetic microspheres comprises: aminating the mixture of the magnetic microspheres and the aminating agent in a water bath at 60°C to 100°C for more than 10 hours, separating the ammoniated magnetic microspheres, washing the ammoniated magnetic microspheres with ultrapure water until the pH value of the effluent is neutral, and drying to obtain ammoniated magnetic microspheres having a tertiary amine structure (-N(CH3)3).

[0066] The alkylating agent comprises 1,2-dichloroethane; the Lewis acid catalyst comprises any one of ferric chloride, aluminum chloride or zinc chloride. During the reaction, the aminated magnetic microspheres undergo an alkylation reaction with 1,2-dichloroethane (CH2Cl-CH2Cl) to connect the alkyl group (-CH2CH2-) to the N atom, so that the amino structure carries a positive charge. Under the action of the Lewis acid catalyst, the tertiary amine structure (-N(CH3)3) attacks the carbon atom in 1,2-dichloroethane through its nucleophilicity, replacing the chlorine atom connected to the carbon atom, thereby connecting a vinyl chain (-CH2CH2-) to the N atom, so that the N atom is converted into a quaternary ammonium ion ([-N + (CH2CH2)3] + , recorded as quaternary ammonium group). To maintain charge balance, the positive charge of the quaternary ammonium group attracts anions in the solution through electrostatic interaction, Cl - As a counter ion, it can combine with the quaternary ammonium group to form a quaternary ammonium group with a chloride ion ([-N + (CH2CH2)3]Cl - ) to obtain a chloride-type magnetic ion exchange resin, in which the counter ion (Cl-) can be replaced by other anions through ion exchange.

[0067] In some embodiments, after completing steps 1 to 3, the magnetic ion exchange resin is rinsed with sodium chloride solution and vacuum dried to constant weight. Rinsing with sodium chloride can remove soluble impurities in the magnetic ion exchange resin.

[0068] In some embodiments, the degree of quaternization of the finally obtained magnetic ion exchange resin is 65% to 75%.

[0069] Unless otherwise specified, the chemicals used in the present invention are all conventional commercially available chemical reagents. These chemicals can be purchased from a number of chemical reagent suppliers and do not require special preparation or synthesis.

[0070] Example 1

[0071] Step S101: Preparation of oleic acid-modified ferric oxide (Fe2O3): 5g of Fe2O3, 50mL of aqueous ammonia, 5mL of oleic acid, and 25mL of acetone were added to a 500mL Erlenmeyer flask containing 400mL of ultrapure water. The mixture was mechanically stirred in an 80°C water bath for 30 minutes to obtain a magnetic particle dispersion. The magnetic particles in the magnetic particle dispersion were separated by adsorption using an external magnet, and the magnetic particles were washed with ultrapure water until the pH of the effluent reached neutral. The prepared magnetic particles were dried at 60°C for 12 hours to obtain oleic acid-modified Fe2O3 particles, designated as OA.

[0072] Step S102: Add 0.1 g of polyvinyl alcohol, 10 g of sodium chloride, and 1 g of gelatin into a 500 mL flask filled with 200 mL of ultrapure water to prepare an aqueous phase.

[0073] Step S103 , 45 g of glycidyl methacrylate, 5 g of divinylbenzene, 5 g of OA, 5 g of dodecanol, 45 g of cyclohexanol, and 0.5 g of a photoinitiator (Irgacure 1173) were added into a beaker to prepare an oil phase.

[0074] In step S104, the oil phase in the beaker is transferred to the aqueous phase in the flask. In an inert nitrogen (N2) environment, a polymerization reaction is carried out under low-pressure ultraviolet (48W, 254nm) irradiation for 2 hours, and the mechanical stirring speed is maintained at 500rpm. After the reaction is completed, the magnetic microspheres are separated and washed alternately with ultrapure water and anhydrous ethanol three times. The magnetic microspheres are dried in a drying oven at 50°C for 12 hours to obtain magnetic microspheres, which are recorded as MOA.

[0075] In step S105, 20 g of MOA and 20 g of trimethylamine hydrochloride were added to a flask containing 100 mL of ultrapure water. The mixture was aminated in an 80°C water bath for 12 hours to produce aminated magnetic microspheres. The aminated magnetic microspheres were separated and rinsed thoroughly with ultrapure water until the pH of the effluent reached neutral, followed by drying at 50°C for 12 hours. The aminated magnetic microspheres were designated QMOA.

[0076] In step S106, 100 mL of anhydrous ethanol and QMOA were added to a three-necked round-bottom flask, with the volume ratio of anhydrous ethanol to QMOA being 4:1. 50 mL of 1,2-dichloroethane and 0.5 g of iron(III) chloride were also added to the three-necked round-bottom flask. The mixture was stirred at 300 rpm in an 80°C water bath for 8 hours to obtain alkylated magnetic microspheres. The microspheres were then rinsed with a 10% sodium chloride solution and vacuum dried at 80°C to constant weight to obtain a magnetic ion exchange resin, designated MGD-OA.

[0077] Example 2

[0078] Step S201: Preparation of silane coupling agent (KH570)-modified iron oxide (Fe3O4): Add 50 mL of deionized water and 100 mL of anhydrous ethanol to a beaker. Adjust the pH of the solution to between 8.0 and 10.0 with aqueous ammonia. Add 1 mL of KH570 to the beaker and hydrolyze for 30 minutes. Then, add 300 mL of deionized water, 5 g of Fe3O4, 50 mL of aqueous ammonia, and 25 mL of acetone. Mechanically stir the mixture in an 80°C water bath for 30 minutes to obtain a magnetic particle dispersion. Separate the magnetic particles from the magnetic particle dispersion using an external magnet, and wash the magnetic particles with ultrapure water until the pH of the effluent reaches neutral. The prepared magnetic particles are dried at 60°C for 12 hours to obtain silane coupling agent-modified Fe3O4 particles, designated MPS.

[0079] Step S202: Add 0.1 g of polyvinyl alcohol, 10 g of sodium chloride, and 1 g of gelatin into a 500 mL flask filled with 200 mL of ultrapure water to prepare an aqueous phase.

[0080] Step S203 , 45 g of glycidyl methacrylate, 5 g of divinylbenzene, 5 g of MPS, 5 g of dodecanol, 45 g of cyclohexanol, and 0.5 g of a photoinitiator (Irgacure 1173) were added into a beaker to prepare an oil phase.

[0081] In step S204, the oil phase in the beaker was transferred to the aqueous phase in the flask. A polymerization reaction was conducted for two hours in an inert nitrogen (N2) environment under low-pressure ultraviolet (48W, 254nm) irradiation, with mechanical stirring maintained at 500 rpm. After the reaction, the magnetic microspheres were separated and washed three times alternately with ultrapure water and anhydrous ethanol. The magnetic microspheres were dried in a drying oven at 50°C for 12 hours to obtain magnetic microspheres, which were designated as MMPS.

[0082] In step S205, 20 g of MMPS and 20 g of trimethylamine hydrochloride are added to a flask containing 100 mL of ultrapure water. The mixture is aminated in an 80°C water bath for 12 hours to produce aminated magnetic microspheres. The aminated magnetic microspheres are separated and carefully rinsed with ultrapure water until the pH of the effluent reaches neutral, and then dried at 50°C for 12 hours. The aminated magnetic microspheres are designated as QMOA.

[0083] In step S206, 100 mL of anhydrous ethanol and QMOA were added to a three-necked round-bottom flask, with the volume ratio of anhydrous ethanol to QMOA being 4:1. 50 mL of 1,2-dichloroethane and 0.5 g of iron(III) chloride were also added to the three-necked round-bottom flask. The mixture was stirred at 300 rpm in an 80°C water bath for 8 hours to obtain alkylated magnetic microspheres. The spheres were then rinsed with 10% sodium chloride solution and vacuum dried at 80°C to constant weight to obtain a magnetic ion exchange resin, designated MGD-MPS.

[0084] Figure 3 The field emission scanning electron microscope images and element distribution diagrams of Example 1 and Example 2 are shown:

[0085] Depend on Figure 3 (a) and Figure 3 (d) shows that the magnetic microspheres MOA and MMPS prepared by steps S104 and S204, respectively, all exhibit a uniform spherical structure, which indicates that the UV-induced polymerization method of the present invention can uniformly coat the resin matrix on the surface of the magnetic particles and construct a uniform three-dimensional cross-linked network to form a uniform sphere. It can be observed that the surface of the sphere is rough and porous, and the rough and porous surface can increase the specific surface area of ​​the magnetic microspheres, thereby enabling the subsequent magnetic resin to provide more active adsorption sites and promote the diffusion of the target anion inside the magnetic resin, thereby enhancing the adsorption and binding ability of the target anion, and contributing to improving the ion exchange efficiency of the magnetic resin. This proves that the UV-induced polymerization method adopted in the present invention can successfully prepare magnetic microspheres with good microscopic morphology.

[0086] Depend on Figure 3 (b) and Figure 3As shown in Figure (e), the surface roughness of the magnetic resins MGD-OA and MGD-MPS prepared in steps S106 and S206, respectively, has decreased. This is because the functionalization steps (steps S105-S106 and S205-S206) introduced quaternary ammonium groups onto the surfaces of MOA and MMPS, forming a modified layer that partially covers the pores. This demonstrates that both Examples 1 and 2 successfully functionalized the surfaces of the magnetic microspheres with quaternary ammonium groups.

[0087] Figure 3 (c) is an enlarged view of a pore on the surface of MGD-OA. Figure 3 (f) is an enlarged view of a pore on the surface of MGD-MPS, which shows that after the functional modification step, the magnetic resin prepared by the method of the present invention still has a porous structure and can provide more active adsorption sites for the target anions in the wastewater.

[0088] Depend on Figure 3 As can be seen from (g) and (h), C, O, N, and Fe elements are evenly distributed in MGD-OA and MGD-MPS, further proving that the present invention utilizes UV-initiated polymerization technology to promote the formation of a stable chemical bonding network between reactant molecules, making the elements evenly dispersed in three-dimensional space.

[0089] Figure 4 The hysteresis loop diagrams of Example 1 and Example 2 are shown. Figure 4 It shows that MGD-OA and MGD-MPS will reach saturation only when the magnetization intensity is ±20000Oe (saturation here means that the magnetization intensity of the material does not increase with the increase of the external magnetic field). The saturation magnetic susceptibility of MGD-OA and MGD-MPS is 6.39emu / g and 2.61emu / g, respectively. This further proves that the method of the present invention can prepare magnetic resins, which can be easily and quickly separated and recovered (recycled) by applying an external magnetic field.

[0090] Figure 5The Zeta potential diagrams of Example 1 and Example 2 are shown. Under different pH conditions, the Zeta potential of magnetic microspheres MOA, MMPS and magnetic resins MGD-OA, MGD-MPS was measured. Due to the functional modification step, quaternary ammonium groups are formed on the surfaces of the magnetic microspheres MOA and MMPS, and MGD-OA and MGD-MPS are positively charged (Zeta potential is greater than 0) under different pH conditions, which proves that the magnetic resin prepared by the present invention can adsorb anions in the solution through electrostatic interaction to achieve anion exchange function. The high positive potential (>15.90mV) means that the magnetic resin has a strong electrostatic interaction and can adsorb and bind target anions through electrostatic attraction, and then use an external magnetic field to separate the magnetic resin and target anions from the wastewater.

[0091] Figure 6 The full XPS spectra of Example 1 and Example 2 are shown (XPS mainly analyzes the surface layer of the material, usually in the range of a few nanometers), wherein the characteristic peak of C1s is located at 286.4eV, the characteristic peak of N1s is located at 399.9eV, the characteristic peak of O1s is located at 532.4eV, and the characteristic peak of Fe2p is located at 711.8eV, indicating that the magnetic microspheres and magnetic resin contain C, N, O and Fe elements. Figure 6 It is clearly seen that: First, the nitrogen content on the surface of the magnetic microspheres is significantly different from that on the surface of the magnetic resin. Taking MOA and MGD-OA as examples, the surface nitrogen content of MOA is 3.20%, while that of MGD-OA is 6.57%. The increase in nitrogen indicates that the functionalization modification step of the present invention achieves functional group modification on the surface of the magnetic microspheres, forming the target quaternary ammonium groups on the surface of the magnetic microspheres. Second, the Fe content on the surface of the magnetic microspheres and the surface of the magnetic resin is relatively low. For example, the surface Fe content of MGD-OA is only 1.65%, demonstrating that the method of the present invention successfully embeds the magnetic particles (modified iron oxide) within the macromolecular skeleton of the resin matrix, achieving the preparation of a magnetic resin with a core-shell structure.

[0092] In summary, the present invention uses glycidyl methacrylate as a monomer, divinylbenzene as a cross-linking agent, and modified iron oxide as magnetic particles to efficiently prepare magnetic ion exchange resins through ultraviolet-initiated polymerization technology. Compared with traditional thermal initiation technology, this method uses photoinitiators to quickly decompose and generate free radicals, completing the copolymerization reaction within 1 to 3 hours, significantly shortening the reaction time. At the same time, it avoids the problem of thermal decomposition of reactants that may be caused by high temperatures, allowing more active sites to participate in the formation of a uniform three-dimensional cross-linked network. The present invention does not require excessive initiators and dispersants, reduces raw material costs, simplifies the cleaning process, and does not require additional ultrasound or heat energy input, greatly reducing energy consumption.

[0093] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0094] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a magnetic ion exchange resin, characterized in that: include: A reaction solution is prepared, wherein the reaction solution comprises: magnetic particles, glycidyl methacrylate, divinylbenzene, and a photoinitiator; the mass ratio of the glycidyl methacrylate to the divinylbenzene is (4.5-10):1; UV-induced polymerization step: irradiating the reaction solution with UV light to initiate a polymerization reaction to obtain magnetic microspheres; Functional modification step: mixing the magnetic microspheres with an amination reagent to carry out an amination reaction to prepare ammoniated magnetic microspheres; mixing the ammoniated magnetic microspheres with an alkylation reagent to carry out an alkylation reaction to prepare a magnetic ion exchange resin.

2. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The power of the ultraviolet light is 10W to 50W, and the wavelength is 200nm to 300nm.

3. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The photoinitiator comprises at least any one of 2-hydroxy-2-methylpropiophenone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

4. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The mass ratio of the photoinitiator to the total mass of the glycidyl methacrylate and the divinylbenzene is 1:(80-200).

5. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The reaction solution further comprises: a porogen, which comprises any one or more of cyclohexanol, n-hexane, n-heptane, n-octane, and toluene; and the mass ratio of the porogen to the total mass of the glycidyl methacrylate and the divinylbenzene is (0.5-1):

1.

6. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The reaction solution further comprises: a dispersant, which comprises any one or more of polyvinyl alcohol, sodium chloride, gelatin, and dodecanol; the mass percentage of the dispersant in the reaction solution is 1% to 8%.

7. The method for preparing a magnetic ion exchange resin according to claim 1, wherein The magnetic particles contain at least one of ferric oxide modified with oleic acid and ferrosoferric oxide modified with a silane coupling agent.

8. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In the functional modification step, the amination reagent comprises any one of trimethylammonium hydrochloride and trimethylammonium hydroxide.

9. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In the functional modification step, the alkylating agent comprises 1,2-dichloroethane.

10. A magnetic ion exchange resin, characterized in that The magnetic ion exchange resin is prepared by the preparation method of any one of claims 1 to 9.

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