Magnetic ion exchange resin, preparation method and use thereof

Abstract

The invention discloses a kind of magnetic ion exchange resin, its preparation method and its use, the method comprising: step 1, glycidyl methacrylate, divinylbenzene, magnetic material and photoinitiator undergo polymerization reaction under light source initiation to obtain magnetic microspheres;Step 2, adding an aminating agent to the magnetic microspheres to generate an aminating reaction to obtain ammoniated magnetic microspheres;Step 3, adding an alkylating agent to the ammoniated magnetic microspheres to generate a nucleophilic substitution reaction to obtain a magnetic ion exchange resin;The alkylating agent includes any one of 1 iodohexanes, 1 chlorohexanes, and 1 bromohexanes.This preparation method can shorten the process cycle, simplify the preparation device, and the prepared magnetic ion exchange resin can efficiently adsorb more target anions, improve adsorption capacity, achieve efficient removal of target anions, and can be well applied to wastewater treatment.

Description

Technical Field

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

[0002] In the current field of environmental governance, ensuring water quality safety and sustainable use of water resources have always been the core points, and the importance of water treatment technology is self-evident.

[0003] As an innovative water treatment material, magnetic ion exchange resin embeds magnetic materials into a polymer network to form a composite system, which has the dual characteristics of chemical adsorption and magnetic control separation. The magnetic response characteristics of the resin are used to achieve rapid separation from the treated water. Compared with the acid-base regeneration process of traditional resins, the operation process is greatly simplified and the use of chemical agents is reduced. In the treatment of complex water quality, magnetic ion exchange resins have shown significant advantages: for example, in high-salt industrial wastewater, due to its strong resistance to ionic interference, it can selectively combine with target pollutants such as heavy metal ions to achieve effective removal of heavy metals and ensure treatment results; in the treatment of electronic electroplating wastewater, the adsorption saturated resin can quickly enrich and recover precious metals through magnetic separation characteristics, realizing the effective utilization of resources and completing the purification of wastewater at the same time.

[0004] Existing methods for preparing magnetic ion exchange resins often use thermal initiation techniques, which result in slow reaction rates, typically lasting 5-10 hours. These processes also involve multiple instruments and equipment, making the process cumbersome. Furthermore, to impart ion exchange properties to the resin, quaternary ammonium groups are introduced to chemically adsorb and bind the target anions. However, the relatively close proximity of quaternary ammonium groups containing short-chain alkyl groups hinders the target anions from entering the resin and being adsorbed. Furthermore, the shorter alkyl chains reduce the contact area between the quaternary ammonium groups and the target anions, preventing efficient adsorption of the target anions, thus affecting the resin's removal efficiency.

[0005] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide a simple and efficient preparation method of magnetic ion exchange resin, shorten the process cycle, simplify the preparation device and increase the adsorption capacity of the resin for target anions, thereby achieving efficient removal of the target anions.

[0007] In order to achieve the above object, the present invention provides a method for preparing a magnetic ion exchange resin, the method comprising:

[0008] Step 1: Glycidyl methacrylate, divinylbenzene, magnetic material and photoinitiator undergo polymerization reaction under the initiation of light source to obtain magnetic microspheres;

[0009] Step 2, adding an amination reagent to the magnetic microspheres to cause an amination reaction to obtain ammoniated magnetic microspheres;

[0010] Step 3: adding an alkylating agent to the aminated magnetic microspheres to undergo a nucleophilic substitution reaction to obtain a magnetic ion exchange resin; the alkylating agent comprises any one of 1-iodohexane, 1-chlorohexane, and 1-bromohexane.

[0011] Optionally, before step 1, the method further comprises: modifying the magnetic material.

[0012] Optionally, in step 1, the light source includes any one of ultraviolet light, visible light, and near-infrared light.

[0013] Optionally, in step 1, the mass ratio of the glycidyl methacrylate to divinylbenzene is (4.5-10):1, and the mass ratio of the glycidyl methacrylate to the magnetic material is (8-10):1.

[0014] Optionally, in step 1, the magnetic material includes any one of ferrous oxide and ferrosoferric oxide.

[0015] Optionally, in step 1, the photoinitiator comprises any one of 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, camphorquinone, and indocyanine green-triethylamine complex.

[0016] Optionally, in step 2, the aminating reagent comprises any one of trimethylammonium hydrochloride and trimethylammonium hydroxide.

[0017] Optionally, step 3 further comprises adding a catalyst, wherein the catalyst comprises any one of ferric chloride, aluminum chloride, and titanium tetrachloride.

[0018] The present invention also provides a magnetic ion exchange resin obtained by the above-mentioned preparation method, wherein the magnetic ion exchange resin has a core-shell structure in which the aminated magnetic microspheres are coated with a magnetic material; the degree of quaternization of the magnetic ion exchange resin is 65%-75%, and the mass ratio of the aminated magnetic microspheres to the magnetic material is (15-25):1.

[0019] The present invention also provides a use of the magnetic ion exchange resin obtained by the above preparation method. The magnetic ion exchange resin is used for wastewater treatment. In the wastewater treatment process, the temperature of the wastewater is 5°C-35°C.

[0020] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0021] 1) Under low-power ultraviolet light irradiation, the photoinitiator absorbs light energy and decomposes to produce free radicals. The free radicals quickly initiate the opening of the carbon-carbon double bond of the glycidyl methacrylate monomer, and a chain polymerization reaction is carried out to form a polymer chain. During the polymerization process, the end of the polymer chain usually carries a free radical, making it active for further reaction. At this time, one double bond of divinylbenzene reacts with the polymer chain carrying the free radical, and the other double bond can further react with other polymer chains or divinylbenzene molecules, thereby connecting the different polymer chains, achieving a cross-linking reaction, and forming a three-dimensional network structure. Because the magnetic material is modified with oleic acid or a silane coupling agent (KH570), the unsaturated double bond in the oleic acid and the acrylic acid group in methacrylic acid glycerol ester are chemically combined through a free radical polymerization reaction. The silane group of the silane coupling agent (KH570) chemically reacts with the surface of the magnetic material to form a silicon-oxygen-metal bond, thereby fixing the silane coupling agent to the surface of the magnetic material. The acrylic acid group of the silane coupling agent (KH570) can participate in the polymerization reaction of the methacrylic acid glycerol monomer or divinylbenzene to form a three-dimensional network structure. Through the above chemical reaction, the magnetic material is coated in the three-dimensional network structure.

[0022] Compared with traditional thermal initiation, the polymerization rate of low-power ultraviolet initiation (reaction time 1h-3h) used in the present invention is significantly higher than that of thermal initiation (reaction time 5h-10h), which greatly improves the speed and efficiency of converting monomers into polymers. In addition, the reaction can be quickly started at room temperature, and more molecules and active sites fully participate in the cross-linking reaction in a short time. The active sites have more opportunities to react with molecules in different directions and positions and will not stay in a local area for a long time, avoiding differences in cross-linking density in local areas, reducing excessive or insufficient local cross-linking, and making the spatial distribution of cross-linking points more random and uniform, which is conducive to forming a uniform three-dimensional network structure, thereby facilitating the diffusion of target anions inside the resin and increasing the adsorption capacity.

[0023] 2) The alkylating agent can extend the carbon chain length of the quaternary ammonium group of the resin to hexyl. On the one hand, the extended carbon chain increases the distance between the quaternary ammonium groups, overcoming the steric hindrance problem of the quaternary ammonium groups, which is conducive to more target anions entering the resin and being adsorbed. On the other hand, the extended carbon chain increases the contact area between the quaternary ammonium group and the target anion, which can efficiently adsorb more target anions and increase the adsorption amount, thereby achieving efficient removal of the target anions, and can be well applied to wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of the preparation method of the magnetic ion exchange resin.

[0025] Figure 2These are SEM images of the magnetic ion exchange resins prepared in Examples 1 and 2 of the present invention; wherein, a is the magnetic ion exchange resin prepared in Example 1, and b is the magnetic ion exchange resin prepared in Example 2.

[0026] Figure 3 The figure shows the adsorption kinetics of phosphate ions by the magnetic ion exchange resins prepared in Examples 1 and 2 of the present invention; wherein a is the magnetic ion exchange resin prepared in Example 1, and b is the magnetic ion exchange resin prepared in Example 2.

[0027] Figure 4 The isothermal equilibrium diagrams of the magnetic ion exchange resins prepared in Examples 1 and 2 of the present invention for adsorbing phosphate ions are shown; wherein a is the magnetic ion exchange resin prepared in Example 1, and b is the magnetic ion exchange resin prepared in Example 2.

[0028] Figure 5 Schematic diagram of the effect of exogenous ions and natural organic matter on the adsorption of phosphate ions by the magnetic ion exchange resin prepared in Examples 1 and 2; wherein, a is a schematic diagram of the effect of exogenous ions on the adsorption of phosphate ions by the resin, and b is a schematic diagram of the effect of natural organic matter on the adsorption of phosphate ions by the resin.

[0029] Figure 6 The following are Fourier transform infrared spectra of the magnetic ion exchange resins prepared in Examples 1 and 2 of the present invention; wherein, a is the magnetic ion exchange resin prepared in Example 1, and b is the magnetic ion exchange resin prepared in Example 2.

[0030] Figure 7 The X-ray diffraction comparison diagrams of the magnetic ion exchange resins prepared in Examples 1 and 2 of the present invention before and after adsorbing phosphate ions. DETAILED DESCRIPTION

[0031] The preparation method of the magnetic ion exchange resin proposed by the present invention is further described in detail below 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 adopt a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiment 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.

[0032] 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.

[0033] The resin described in this article is a chloride-type ion exchange resin, which is inherently bound to chloride ions. Chloride ions have a larger ionic radius and a lower charge density, resulting in a weaker electrostatic attraction between them and the positively charged quaternary ammonium groups on the resin surface. When the resin is placed in a solution containing target anions (such as phosphate ions), the chloride ions on the resin are replaced by the phosphate ions due to the higher charge density of the phosphate ions and the stronger electrostatic attraction between them and the positively charged quaternary ammonium groups on the resin surface, thereby achieving ion exchange.

[0034] As described in the background, the traditional thermal initiation technique for preparing magnetic ion exchange resins is slow, time-consuming, and complex, requiring complicated preparation equipment and operations. Furthermore, the quaternary ammonium groups in the resin, which contribute to ion exchange, contain short-chain alkyl groups, which are relatively close together, hindering the entry and adsorption of target anions. Furthermore, the short alkyl chains of the quaternary ammonium groups reduce their contact area with the target anions, preventing efficient adsorption of the target anions and thus reducing the resin's effectiveness in removing the target anions.

[0035] In order to solve the above problems, the present invention provides a method for preparing a magnetic ion exchange resin, wherein glycidyl methacrylate, divinylbenzene, a magnetic material and a photoinitiator are first polymerized under the initiation of a light source to obtain magnetic microspheres; then an amination reagent is added to the magnetic microspheres to undergo an amination reaction to obtain ammoniated magnetic microspheres; finally, an alkylating agent is added to the ammoniated magnetic microspheres to undergo a nucleophilic substitution reaction to obtain a magnetic ion exchange resin. At room temperature, ultraviolet light is used to induce the decomposition of the photoinitiator to produce free radicals, which rapidly initiate the polymerization reaction of glycidyl methacrylate monomers and the cross-linking reaction of the polymer chain with divinylbenzene, promoting the formation of a uniform three-dimensional network structure, which is beneficial to the diffusion of target anions inside the resin; at the same time, the alkylating agent extends the carbon chain length of the quaternary ammonium group of the resin to hexyl, thereby increasing the spacing between the quaternary ammonium groups and increasing the contact area between the quaternary ammonium groups and the target anions, thereby increasing the adsorption capacity of the resin on the target anions, thereby achieving efficient removal of the target anions. Specifically, as Figure 1 As shown, the present invention provides a method for preparing a magnetic ion exchange resin, the method comprising:

[0036] Step 1: Glycidyl methacrylate, divinylbenzene, magnetic material and photoinitiator undergo polymerization reaction under the initiation of light source to obtain magnetic microspheres.

[0037] The aqueous phase consists of polyvinyl alcohol, sodium chloride, and gelatin, while the oil phase consists of glycidyl methacrylate, divinylbenzene, a magnetic material, dodecanol, cyclohexanol, and a photoinitiator. The aqueous and oil phases are mixed and stirred, then irradiated with ultraviolet light. At room temperature, the photoinitiator absorbs light energy and decomposes to produce free radicals. These free radicals rapidly initiate the opening of the carbon-carbon double bonds of the glycidyl methacrylate monomer, leading to a chain polymerization reaction to form polymer chains. During the polymerization process, the ends of the polymer chains often carry free radicals, making them reactive for further reaction. At this point, one double bond of the divinylbenzene reacts with the polymer chain carrying the free radical, while the other double bond can further react with other polymer chains or divinylbenzene molecules, thus connecting the different polymer chains and achieving cross-linking reactions. This three-dimensional network structure encapsulates the magnetic material, ultimately yielding magnetic microspheres. After the reaction, the magnetic microspheres are separated, washed three times alternately with ultrapure water and anhydrous ethanol, and dried in a drying oven.

[0038] It is worth noting that since the free radicals generated by the photoinitiator will react with oxygen, the above-mentioned polymerization and cross-linking reactions need to be carried out in an inert environment.

[0039] Dodecanol acts as a dispersant to help improve the dispersion of materials in the resin, so that various materials are evenly distributed inside the resin.

[0040] Cyclohexanol, as a porogen, is partially or completely removed after washing, forming a pore structure inside the magnetic microspheres, increasing their porosity, and thus improving the adsorption performance of the resin.

[0041] In some embodiments, the light source includes any one of ultraviolet light, visible light, and near-infrared light. In this embodiment, the light source is ultraviolet light, and the conditions for ultraviolet light initiation are: power 10W-50W, wavelength 200nm-300nm. Compared with traditional thermal initiation, low-power ultraviolet light initiation not only greatly improves the speed and efficiency of monomer to polymer conversion, but also can quickly start the reaction at room temperature. More molecules and active sites fully participate in the cross-linking reaction in a short time, and the active sites have more opportunities to react with molecules in different directions and positions. They will not stay in a local area for a long time, avoiding differences in cross-linking density in local areas, reducing excessive or insufficient local cross-linking, and making the distribution of cross-linking points in space more random and uniform, which is conducive to the formation of a uniform three-dimensional network structure, thereby facilitating the diffusion of target anions inside the resin and increasing the adsorption capacity.

[0042] In some embodiments, the mass ratio of glycidyl methacrylate to divinylbenzene is (4.5-10):1, and the mass ratio of glycidyl methacrylate to magnetic material is (8-10):1.

[0043] In some embodiments, the photoinitiator comprises any one of 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, camphorquinone, and indocyanine green-triethylamine complex.

[0044] In some embodiments, the magnetic material includes any one of ferrous oxide and ferrosoferric oxide.

[0045] When ferric oxide is used as the magnetic material, it is modified with oleic acid. Oleic acid is a fatty acid with long-chain alkyl groups. The long-chain alkyl moieties of the oleic acid molecule bind to the surface of ferric oxide through hydrophobic interactions, reducing its surface energy and making it more hydrophobic, thereby improving its dispersibility in organic solvents. Oleic acid also forms a stable surface structure through coordination and adsorption with the ferrite surface, thereby increasing its stability under various environmental conditions, especially humid environments. Furthermore, the unsaturated double bonds of oleic acid chemically bond with the acrylic acid groups of glycerol methacrylate through free radical polymerization, effectively coating the ferric oxide. The modification steps are as follows: A certain amount of ferric oxide, ammonia, oleic acid, and acetone are added to ultrapure water and stirred in a water bath. The resulting brown dispersion is separated using a magnet and washed with ultrapure water until the pH is neutral. After washing, the dispersion is dried in a drying oven. The modified ferric oxide is labeled OA, and the magnetic microspheres prepared with OA are labeled MOA.

[0046] When ferroferric oxide is used as the magnetic material, a silane coupling agent is required to modify the ferroferric oxide. On the one hand, the end of the silane coupling agent containing a silicon atom can react with the surface of inorganic materials, and the end containing an organic group can react with other organic materials, thereby improving the dispersibility of the ferroferric oxide and enhancing its compatibility with organic materials and interfacial adhesion. On the other hand, the silane group of the silane coupling agent chemically reacts with the surface of the ferroferric oxide to form a silicon-oxygen-metal bond, thereby fixing the silane coupling agent to the surface of the ferroferric oxide. The acrylic acid group of the silane coupling agent can participate in the polymerization reaction of methacrylate monomer or divinylbenzene to form a three-dimensional network structure, thereby effectively achieving the coating effect on the ferroferric oxide. The specific steps of the modification are the same as the preparation steps of OA, except that the silane coupling agent must be hydrolyzed before modification. The hydrolysis step is: a certain amount of deionized water and anhydrous ethanol are mixed, the pH value of the solution is adjusted to between 8.0 and 10.0 with ammonia water, and the silane coupling agent is added to the solution for hydrolysis. Through hydrolysis, the silicon-ethoxy bonds in the silane coupling agent break, forming chemically reactive silanol groups. These silanol groups can covalently bond with hydroxyl groups or other surface functional groups on the inorganic material, strengthening the bond between the silane coupling agent and the inorganic material, thereby increasing interfacial bonding strength and improving the mechanical properties and stability of the resin. The modified ferrosoferric oxide is labeled MPS, and the magnetic microspheres prepared using MPS are labeled MMPS.

[0047] Step 2: adding an amination reagent to the magnetic microspheres to cause an amination reaction to obtain ammoniated magnetic microspheres.

[0048] After the magnetic microspheres are prepared, an amination reagent is added to the microspheres to initiate an amination reaction in a water bath. The amination reagent is nucleophilic, and its nitrogen atom uses its lone pair of electrons to attack the epoxy group in the glycidyl methacrylate, causing a ring-opening reaction, thereby producing ammoniated magnetic microspheres with a tertiary amine structure. After the reaction is complete, the ammoniated magnetic microspheres are separated, washed with ultrapure water until the pH is neutral, and dried in a drying oven.

[0049] In some embodiments, the aminating agent comprises any one of trimethylamine hydrochloride and trimethylamine hydroxide.

[0050] Step 3: adding an alkylating agent to the aminated magnetic microspheres to undergo a nucleophilic substitution reaction to obtain a magnetic ion exchange resin; the alkylating agent is any one of 1-iodohexane, 1-chlorohexane, and 1-bromohexane.

[0051] The aminated magnetic microspheres are dissolved in anhydrous ethanol, and an alkylating agent is added to the solution, which is stirred in a water bath to cause a nucleophilic substitution reaction. The tertiary amine structure in the aminated magnetic microspheres is nucleophilic, and its nitrogen atom uses its lone pair electrons to attack the carbon atom connected to iodine in the alkylating agent (such as 1-iodohexane). The iodine ion leaves, and the nitrogen atom carries a positive charge and forms a quaternary amine group, thereby obtaining a magnetic ion exchange resin. The magnetic ion exchange resin has a core-shell structure of aminated magnetic microspheres coated with magnetic material. The degree of quaternization of the magnetic ion exchange resin is 65%-75%, and the mass ratio of aminated magnetic microspheres to magnetic material is (15-25):1. The alkylating agent extends the carbon chain length of the quaternary ammonium group of the resin to hexyl. On the one hand, the extended carbon chain increases the spacing between the quaternary ammonium groups, overcoming the steric hindrance problem of the quaternary ammonium groups, which is conducive to more target anions entering the resin and being adsorbed. On the other hand, the extended carbon chain increases the contact area between the quaternary ammonium group and the target anion, which can efficiently adsorb more target anions and increase the adsorption amount, thereby achieving efficient removal of the target anion.

[0052] In some embodiments, a catalyst is further added to the solution to promote the nucleophilic substitution reaction. The catalyst comprises any one of ferric chloride, aluminum chloride, and titanium tetrachloride.

[0053] After step 3, the process further includes rinsing the obtained magnetic ion exchange resin with a sodium chloride solution to remove soluble impurities in the resin, and then drying the resin in a vacuum drying oven. The OA-coated magnetic ion exchange resin is labeled as MGD-OA, and the MPS-coated magnetic ion exchange resin is labeled as MGD-MPS.

[0054] Example 1

[0055] (1) Preparation of modified ferric oxide (OA): 5 g of ferric oxide, 50 mL of ammonia, 5 mL of oleic acid, and 25 mL of acetone were added to a conical flask containing 400 mL of ultrapure water. The solution was mechanically stirred in a water bath at 353 K for 30 min. The brown dispersion was separated by magnet and washed with ultrapure water until the pH value was neutral. After washing, it was dried in a drying oven at 333 K for 12 h.

[0056] (2) Preparation of magnetic microspheres (MOA) using OA: 0.1 g of polyvinyl alcohol, 10 g of sodium chloride, and 1 g of gelatin were added to a flask containing 200 mL of ultrapure water as the aqueous phase. 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 2-hydroxy-2-methylpropiophenone were added to a beaker as the oil phase. The oil phase and the aqueous phase were mixed and stirred at 500 rpm. The polymerization reaction was carried out under 48 W, 254 nm ultraviolet light in a nitrogen environment for 2 h. After the reaction, the magnetic microspheres were separated and washed alternately with ultrapure water and anhydrous ethanol three times, and then dried in a drying oven at 323 K for 12 h.

[0057] (3) Preparation of OA-coated magnetic ion exchange resin (MGD-OA): 20 g of MOA and 20 g of trimethylamine hydrochloride were added to a flask containing 100 mL of ultrapure water and subjected to an amination reaction in a 353 K water bath for 12 h. After the reaction, the ammoniated magnetic microspheres were separated and washed with ultrapure water until the pH was neutral. The ammoniated magnetic microspheres were then dried in a 323 K drying oven for 12 h. Subsequently, 80 mL of anhydrous ethanol and 20 mL of ammoniated magnetic microspheres were added to a three-necked round-bottom flask, and then 50 mL of 1-iodohexane and 0.5 g of ferric chloride were added thereto and stirred at 300 rpm in a 353 K water bath for 8 h to obtain a magnetic ion exchange resin. Finally, the resin was rinsed with 10% sodium chloride solution and dried in a vacuum drying oven at 80 °C to constant weight.

[0058] The structure of MGD-OA is as follows Figure 2 As shown in a; the adsorption kinetics of MGD-OA is shown in Figure 3 As shown in a; the isothermal equilibrium diagram of MGD-OA is shown in Figure 4 As shown in a; the effect of exogenous ions on the adsorption of phosphate ions by MGD-OA is shown in Figure 5 As shown in a, the effect of natural organic matter on the adsorption of phosphate ions by MGD-OA is as follows Figure 5 As shown in b; the Fourier transform infrared spectrum of MGD-OA is shown in Figure 6 As shown in a; X-ray diffraction of MGD-OA before and after adsorption of phosphate ions is shown in Figure 7 shown.

[0059] Example 2

[0060] (1) Preparation of modified ferrosoferric oxide (MPS): 50 mL of deionized water and 100 mL of anhydrous ethanol were added to a beaker. The pH of the solution was adjusted to between 8.0 and 10.0 with aqueous ammonia. 1 mL of silane coupling agent (KH570) was added to the solution and hydrolyzed for 30 min. Then, 300 mL of deionized water, 5 g of ferrosoferric oxide, 50 mL of aqueous ammonia, and 25 mL of acetone were added. The solution was mechanically stirred in a water bath at 353 K for 30 min. The black dispersion was separated with a magnet and washed with ultrapure water until the pH was neutral. After washing, it was dried in a drying oven at 333 K for 12 h.

[0061] (2) Preparation of magnetic microspheres (MMPS) using MPS: 0.1 g of polyvinyl alcohol, 10 g of sodium chloride, and 1 g of gelatin were added to a flask containing 200 mL of ultrapure water as the aqueous phase. 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 2-hydroxy-2-methylpropiophenone were added to a beaker as the oil phase. The oil phase and the aqueous phase were mixed and stirred at 500 rpm. The polymerization reaction was carried out under 48 W, 254 nm ultraviolet light in a nitrogen environment for 2 h. After the reaction, the magnetic microspheres were separated and washed alternately with ultrapure water and anhydrous ethanol three times, and then dried in a drying oven at 323 K for 12 h.

[0062] (3) Preparation of MPS-coated magnetic ion exchange resin (MGD-MPS): 20 g of MMPS and 20 g of trimethylamine hydrochloride were added to a flask containing 100 mL of ultrapure water and subjected to an amination reaction in a 353 K water bath for 12 h. After the reaction, the ammoniated magnetic microspheres were separated and washed with ultrapure water until the pH was neutral. The ammoniated magnetic microspheres were then dried in a 323 K drying oven for 12 h. Subsequently, 80 mL of anhydrous ethanol and 20 mL of ammoniated magnetic microspheres were added to a three-necked round-bottom flask, and then 50 mL of 1-iodohexane and 0.5 g of ferric chloride were added thereto and stirred at 300 rpm in a 353 K water bath for 8 h to obtain a magnetic ion exchange resin. Finally, the resin was rinsed with 10% sodium chloride solution and dried in a vacuum drying oven at 80 °C to constant weight.

[0063] The structure of MGD-MPS is as follows Figure 2 As shown in b; the adsorption kinetics of MGD-MPS is shown in Figure 3 As shown in b; the isothermal equilibrium diagram of MGD-MPS is shown in Figure 4 As shown in b; the effect of exogenous ions on the adsorption of phosphate ions by MGD-MPS is shown in Figure 5 As shown in a, the effect of natural organic matter on the adsorption of phosphate ions by MGD-MPS is as follows Figure 5 As shown in b; the Fourier transform infrared spectrum of MGD-MPS is shown in Figure 6 As shown in b; X-ray diffraction of MGD-MPS before and after adsorption of phosphate ions is shown in Figure 7 shown.

[0064] like Figure 2 As shown, MGD-OA and MGD-MPS are both spherical structures, with ammoniated magnetic microspheres as the shell and magnetic material as the core (not shown in the figure).

[0065] In order to further explore the adsorption effect of the resin on phosphate ions, the results of the adsorption kinetics of MGD-OA prepared in Example 1 and MGD-MPS prepared in Example 2 were fitted, as shown in FIG. Figure 3 As shown in Figures a and b, MGD-OA or MGD-MPS were added to the wastewater at concentrations of 5 mg / L, 10 mg / L, and 20 mg / L, respectively. As the adsorption time increased, the higher the MGD-OA or MGD-MPS concentration, the greater the adsorption amount. This is because more quaternary ammonium groups facilitate chemical adsorption of more phosphate ions through electrostatic attraction. Throughout the adsorption process, the adsorption rate was high within the first 40 minutes and then decreased after 40 minutes, indicating that the adsorption was not solely monolayer. Monolayer adsorption occurs through van der Waals forces or hydrogen bonding, where only one molecule is adsorbed at each adsorption site, without interaction between the adsorbed molecules. Longer adsorption times increase the adsorption rate. However, in this case, the adsorption rate decreased with longer adsorption times, suggesting the possibility of multilayer adsorption or other more complex adsorption processes.

[0066] like Figure 4 As shown in Figures a and b, as the concentration of MGD-OA or MGD-MPS increases, the adsorption capacity increases with lower wastewater temperature. When the MGD-OA or MGD-MPS concentration is 40 mg / mL, a wastewater temperature between 15°C and 35°C is beneficial for maintaining high adsorption capacity. Furthermore, further research indicates that the resin of the present invention can still be used at a wastewater temperature of 5°C, with adsorption capacity comparable to that at 15°C. During use, if the temperature is too low, the exchange reaction rate may decrease and the resin may be damaged; if the temperature is too high, the resin may degrade and fail.

[0067] like Figure 5 As shown in a, exogenous ions HCO3 were added to the MGD-OA or MGD-MPS solution. - After that, HCO3 - Hydrolysis produces OH - Increase the pH value of the solution. In an alkaline environment, the target anion (phosphate ion) may be more likely to form precipitation with some metal ions, thereby promoting the removal of phosphate ions. Add exogenous ions CO3 to the solution. 2- Afterwards, due to CO3 2-It will compete for the adsorption sites on the resin surface, and the removal of phosphate ions will be significantly inhibited. The removal of phosphate by the resin mainly depends on Cl - During the ion exchange process, when the phosphate ions and Cl - When present, Cl - It will exchange ions with phosphate ions, so that the phosphate ions are adsorbed or fixed by the resin, thereby achieving the purpose of removing phosphate ions; but when Cl - When the amount of ClO is too much, the ion exchange process that is originally beneficial to the removal of phosphate ions will be reversed, that is, the phosphate ions originally adsorbed by the resin may be replaced by ClO. - The exchanged ions are then released back into the solution, hindering the removal of phosphate ions and resulting in a lower removal rate. 2- It can compete for more adsorption sites on the resin surface, resulting in a significant decrease in the amount of phosphate ions adsorbed by the resin. This is because SO4 2- With a smaller ionic radius, it is easier to approach the adsorption sites on the resin surface; at the same time, the charge density is high, the interaction force with the resin surface is stronger, and it can occupy the adsorption sites more effectively; when SO4 2- After occupying the adsorption sites, phosphate ions are difficult to be adsorbed onto the resin surface, which significantly inhibits the adsorption process of phosphate ions. Figure 5 As shown in (b), as the concentration of hyaluronic acid gradually increases, the adsorption amount of phosphate ions by MGD-OA or MGD-MPS remains basically unchanged, proving that natural organic matter has almost no effect on the resin's adsorption of anionic pollutants.

[0068] Depend on Figure 6 It can be seen that after the amination reaction and nucleophilic substitution reaction of the magnetic microspheres (MOA, MMPS), the Fourier transform infrared spectrum changed significantly, proving that the magnetic ion exchange resins (MGD-OA, MGD-MPS) were successfully obtained. Taking MGD-MPS as an example, the amination process changed the 1107.74 cm -1 There is an obvious secondary alcohol peak at -COC (909.15 cm -1 ) almost disappeared, and the C=O bond decreased from 1728.87cm -1 Transfer to 1724.64cm -1 , indicating that the amination reaction was successful. The nucleophilic substitution process produced an NH bond (1640.14 cm -1 )、CN key(1485.91cm -1 ) bending vibration, alkyl-CH2 (1388.73cm -1 ) and -CH3 (2954.22cm -1 ) bends at an asymmetric angle, indicating that the nucleophilic substitution reaction is successful.

[0069] In addition, the -OH stretching vibration absorption peak in MGD-OA adsorbed with phosphate ions shifted to 3393.66 cm -1 The -OH stretching vibration absorption peak of MGD-MPS adsorbing phosphate ions shifts to 3421.12 cm -1 , indicating that there is a hydrogen bond interaction between phosphate ions and -OH groups; the CO stretching vibration peak in MGD-OA adsorbed with phosphate ions shifts to 1156.33 cm -1 The CO stretching vibration peak in MGD-MPS with adsorbed phosphate ions shifts to 1150 cm -1 , indicating that there is a hydrophobic interaction between the resin and phosphate ions.

[0070] like Figure 7 As shown in the figure, before and after the adsorption of phosphate ions, the crystal structure of ferric oxide and ferrosoferric oxide of MGD-OA or MGD-MPS did not change, and the strong magnetic and chemical stability was maintained.

[0071] In summary, the method of the present invention adopts low-power UV initiation technology to prepare magnetic ion exchange resin. Compared with traditional thermal initiation, the polymerization rate of low-power UV initiation (reaction time 1h-3h) is significantly higher than that of thermal initiation (reaction time 5h-10h), which greatly improves the speed and efficiency of monomer to polymer conversion. In addition, the reaction can be quickly started at room temperature, more molecules and active sites participate in the cross-linking reaction, and the active sites have more opportunities to react with molecules in different directions and positions, not limited to local areas, reducing the situation of excessive or insufficient local cross-linking, and making the distribution of cross-linking points in space more random and uniform. , which is conducive to the formation of a uniform three-dimensional network structure, thereby facilitating the diffusion of target anions inside the resin and increasing the adsorption capacity; at the same time, the alkylating agent can extend the carbon chain length of the quaternary ammonium group of the resin to hexyl. On the one hand, the extended carbon chain increases the spacing between the quaternary ammonium groups, overcoming the spatial steric hindrance problem of the quaternary ammonium groups, which is conducive to more target anions entering the resin and being adsorbed. On the other hand, the extended carbon chain increases the contact area between the quaternary ammonium group and the target anion, which can efficiently adsorb more target anions and increase the adsorption capacity, thereby achieving efficient removal of target anions and can be well applied to wastewater treatment.

[0072] 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: The method includes: Step 1: Glycidyl methacrylate, divinylbenzene, magnetic material and photoinitiator undergo polymerization reaction under the initiation of light source to obtain magnetic microspheres; Step 2, adding an amination reagent to the magnetic microspheres to cause an amination reaction to obtain ammoniated magnetic microspheres; Step 3: adding an alkylating agent to the aminated magnetic microspheres to undergo a nucleophilic substitution reaction to obtain a magnetic ion exchange resin; the alkylating agent comprises any one of 1-iodohexane, 1-chlorohexane, and 1-bromohexane.

2. The method for preparing a magnetic ion exchange resin according to claim 1, wherein Before step 1, the method further comprises: modifying the magnetic material.

3. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In step 1, the light source includes any one of ultraviolet light, visible light, and near-infrared light.

4. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In step 1, the mass ratio of the glycidyl methacrylate to divinylbenzene is (4.5-10):1, and the mass ratio of the glycidyl methacrylate to the magnetic material is (8-10):

1.

5. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In step 1, the magnetic material includes any one of ferrous oxide and ferrosoferric oxide.

6. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In step 1, the photoinitiator comprises any one of 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, camphorquinone, and indocyanine green-triethylamine complex.

7. The method for preparing a magnetic ion exchange resin according to claim 1, wherein In step 2, the aminating reagent comprises any one of trimethylammonium hydrochloride and trimethylammonium hydroxide.

8. The method for preparing a magnetic ion exchange resin according to claim 1, wherein Step 3 further comprises adding a catalyst, wherein the catalyst comprises any one of ferric chloride, aluminum chloride, and titanium tetrachloride.

9. A magnetic ion exchange resin obtained according to the preparation method according to any one of claims 1 to 8, characterized in that: The magnetic ion exchange resin is a core-shell structure of the aminated magnetic microspheres coated with magnetic material; the degree of quaternization of the magnetic ion exchange resin is 65%-75%, and the mass ratio of the aminated magnetic microspheres to the magnetic material is (15-25):

1.

10. Use of a magnetic ion exchange resin obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The magnetic ion exchange resin is used for wastewater treatment. In the wastewater treatment process, the temperature of the wastewater is 5°C-35°C.

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