Magnetic imprinted polymer for separating perrhenate ions as well as preparation method and application of magnetic imprinted polymer

Abstract

The invention discloses a magnetic imprinted polymer for separating perrhenate ions as well as a preparation method and application of the magnetic imprinted polymer, and belongs to the field of hydrometallurgy. The method comprises the following steps: firstly, preparing Fe3O4 (at) mSiO2, and then carrying out sulfydryl modification on the Fe3O4 (at) mSiO2 by utilizing 3-mercaptopropyltrimethoxysilane (MPTMS), so as to obtain the Fe3O4 (at) mSiO2 (at) S-H microspheres. Then by taking perrhenic acid radical (ReO4) as template ions, N-vinyl imidazole (NVI) as a functional monomer, N 'N-methylene bisacrylamide (MBA) as a cross-linking agent, benzoin dimethyl ether (DMPA) as a photoinitiator and a mixed solution of water and ethanol as a pore-forming agent, carrying out hydrothermal reaction to obtain a porous polymer; the perrhenate ion magnetic imprinted polymer (ReO4--MIIPs) with high selectivity and high adsorption capacity is prepared by adopting a sulfydryl-alkene click polymerization method. And the rhenium is used as an adsorbent for enriching and recovering rhenium elements in a rhenium-containing secondary resource solution, so that the separation effect and the recovery efficiency of rhenium are remarkably improved. Compared with a traditional perrhenic acid radical ion imprinting material, the magnetic ion imprinting polymer prepared by combining an ion imprinting technology with a magnetic separation technology is good in stability, high in selectivity, large in adsorption capacity, high in adsorption rate, high in desorption rate and good in regeneration performance; reO4 <-> ions in a rhenium-containing secondary resource solution can be directionally separated, extracted and recycled, and a solution is provided for efficient recovery of secondary resource valuable metals.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrometallurgy, and particularly relates to a magnetic imprinted polymer for separating perrhenate ions, its preparation method, and its application. Background Technology

[0002] Rhenium and its compounds, due to their unique physical and chemical properties, are widely used in industries such as aerospace, petrochemicals, metal coatings, and semiconductors. In recent years, with the rapid development of the aerospace industry, market demand for rhenium and its compounds has continued to rise. However, rhenium is extremely rare in the Earth's crust and typically does not form independent deposits, but is mainly found as an associated mineral in molybdenite and copper-rhenium sulfide ores. Because the grade of rhenium in raw ore is generally low, its recovery faces significant technical challenges and economic costs. Furthermore, in existing industrial systems, rhenium is mostly recovered as a byproduct of copper or molybdenum smelting processes.

[0003] Currently, secondary resources for rhenium extraction include smelting wastewater, spent catalysts, and rhenium-containing alloy waste. After rhenium in rhenium-containing materials transforms from a solid to a liquid phase and enters the solution, it is released as perrhenate ions (ReO4). - Rhenium exists in acidic environments, and solutions containing rhenium have complex compositions, with high and diverse content of competing ions. Traditional rhenium extraction techniques generally suffer from insufficient stability, limited adsorption capacity, and poor selectivity under acidic conditions. Against this backdrop, the development of novel functional adsorbent materials with good stability, high adsorption capacity, and strong selectivity under acidic conditions is particularly important. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetically imprinted polymer for separating perrhenate ions, its preparation method, and its application, which has good engineering application value and economic value.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a magnetically imprinted polymer for separating perrhenate ions, wherein the method uses perrhenate (ReO4) ions. ⁻ Using N-vinylimidazole (NVI) as the template ion, N'N-methylenebisacrylamide (MBA) and pentaerythritol tetra-3-mercaptopropylene (PTM) as crosslinking agents, benzoin dimethyl ether (DMPA) as the photoinitiator, and a water-ethanol mixture as the pore-forming agent, a high-rhenate ion magnetic imprinted polymer (ReO4) with high selectivity and high adsorption capacity was prepared by mercapto-olefin click polymerization. - -MIIPs).

[0007] The method specifically includes the following steps:

[0008] Step (1), Preparation of Fe3O4 magnetic nanoparticles: FeCl3·6H2O, sodium acetate, and polyethylene glycol-2000 were added sequentially to ethylene glycol, and the mixture was ultrasonically treated for 30-50 min. The mixture was then transferred to a reaction vessel and heated at 180-200℃ for 12-18 h to obtain a black solid product. After the reaction, the product was washed with ethanol and water, and then vacuum dried at 60℃ for 24 h to obtain Fe3O4 magnetic nanoparticles.

[0009] Step (2), Preparation of Fe3O4@mSiO2: The Fe3O4 magnetic nanoparticles prepared in step (1) are dispersed in a mixed solution of cyclohexane, water and isopropanol. Urea and hexadecyltrimethylammonium bromide are added, and the mixture is stirred for 0.5-1 h. Tetraethyl orthosilicate is added, and the mixture is reacted in an oil bath at 60-90℃ for 15-20 h with stirring. After the reaction is completed, the mixture is washed with ethanol and water 3-4 times in sequence. The product is separated using an external magnetic field and freeze-dried for 12-24 h to obtain Fe3O4@mSiO2.

[0010] Step (3), Preparation of Fe3O4@mSiO2@SH: Disperse the Fe3O4@mSiO2 obtained in step (2) into ethanol, sonicate for 0.5-1h, adjust the pH of the solution to 8-10, add 3-mercaptopropyltrimethoxysilane dropwise, and react in a water bath at 35-40℃ for 10-15h with stirring. After the reaction, wash with ethanol and water 3-4 times in sequence, separate the product using an external magnetic field, and freeze-dry for 12-24h to obtain Fe3O4@mSiO2@SH.

[0011] Step (4), ReO4 - Preparation of MIIPs magnetic imprinted polymers: 1 mL of potassium perrhenate (100-200 mg / L) and N-vinylimidazole were dissolved in an aqueous ethanol solution and sonicated for 0.5-1 h. 0.1-0.3 g of Fe3O4@mSiO2@SH microspheres were added, and the mixture was reacted in a water bath at 45-50 °C with stirring for 10-15 h for prepolymerization. N,N-methylenebisacrylamide and pentaerythritol tetra-3-mercaptopropylene were added, along with 0.3-0.6 g of benzoin dimethyl ether photoinitiator. The mixture was subjected to ultraviolet light irradiation for 3-5 h for mercapto-olefin click polymerization. After the reaction, the mixture was washed 3-4 times sequentially with anhydrous ethanol, dilute nitric acid, and deionized water. The resulting product was separated using an external magnetic field and freeze-dried for 12-24 h to obtain the ReO4. - -MIIPs (Magnetic Imprinted Polymers)

[0012] In step (1) above, the ratio of FeCl3·6H2O, sodium acetate and polyethylene glycol-2000 is 1~3mol: 5~8mol: 100~180g.

[0013] In step (2) above, the volume ratio of the mixed solution of cyclohexane, water and isopropanol is 30~100mL:30~100mL:1~3mL.

[0014] In step (2) above, the ratio of urea, hexadecyltrimethylammonium bromide and tetraethyl orthosilicate is 1~5g: 1~5g: 1~10mL.

[0015] In step (3) above, the ratio of Fe3O4@mSiO2 to 3-mercaptopropyltrimethoxysilane is 0.2~1g:0.3~1.5mL.

[0016] In step (4) above, the ratio of potassium perrhenate, N-vinylimidazole, N,N-methylenebisacrylamide and pentaerythritol tetra-3-mercaptopropylene is 1 mL: 3~6 mmol: 2~6 mmol: 1~3 mmol.

[0017] The magnetically imprinted polymer prepared using the method described above can be used to separate perrhenate ions from rhenium-containing secondary resource solutions. The specific separation steps are as follows:

[0018] (a) Adsorption performance of magnetically imprinted polymer: 5-50 mg of magnetically imprinted polymer particles were added to 10-60 mL of a secondary resource solution containing rhenium. The reaction system was placed under closed conditions and room temperature for adsorption. The adsorption time was 5-120 min.

[0019] (b) Desorption performance of magnetically imprinted polymer: The magnetically imprinted polymer particles after the adsorption in step (a) are separated by an external magnetic field and then placed in an ammonia solution for desorption at room temperature for 3-12 hours. After desorption, the magnetically imprinted polymer is recovered by an external magnetic field and recycled.

[0020] In step (a) above, the ratio of magnetically imprinted polymer particles to rhenium-containing secondary resource solution is (5-50 mg):(10-60 mL); the adsorption time in step (a) is 5-120 min.

[0021] The rhenium content in the rhenium-containing secondary resource solution is 5-100 mg / L.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. Integration of magnetic separation technology

[0024] Rapid magnetic response separation (separation time < 30 seconds) was achieved using Fe3O4@mSiO2@SH microsphere carriers, which improved efficiency by more than 90% compared to traditional centrifugation / filtration methods and effectively avoided the problem of clogging of imprint sites during solid-liquid separation.

[0025] 2. Innovation in thiol-olefin click polymerization

[0026] Imprinted polymer backbones were prepared by mercapto-olefin click polymerization, which has a polymerization rate 5-8 times faster than traditional free radical polymerization and mild reaction conditions (room temperature light initiation), effectively reducing the risk of template ion leakage.

[0027] 3. Multi-faceted collaborative identification system

[0028] A core-shell magnetically imprinted polymer, prepared using Fe3O4@mSiO2 as the magnetic core via surface ion imprinting, exhibits an ultra-high adsorption / desorption rate compared to polymers prepared by traditional imprinting methods. In terms of chemical recognition, the N-vinylimidazolium functional monomer forms multiple hydrogen bonds with ReO4⁻; in terms of spatial recognition, the mesoporous structure of mSiO2 (pore size 3-5 nm) provides sufficient imprinting cavity; and in terms of electrostatic recognition, the protonated nitrogen atom in the imprinted ring shrinks and binds to ReO4⁻ through electrostatic attraction. - The spatial distance, while acting as an electron donor, gives lone pairs of electrons to Re atoms with empty orbitals, forming stable N→Re coordinate bonds.

[0029] 4. Breakthrough in recyclability

[0030] After 10 adsorption-desorption cycles, the adsorption capacity retention rate is >92% (compared to <70% for traditional materials), and the magnetic recovery rate remains above 99.3%, significantly reducing the cost of secondary resource processing.

[0031] 5. Adaptability to complex systems

[0032] In wastewater containing interfering ions such as Cl⁻, NO⁻, and SO₄²⁻ (concentration ratio 100:1), the separation coefficient for ReO₄⁻ reached as high as 4.2 × 10⁻⁶. 5 It is two orders of magnitude better than conventional imprint materials. Attached Figure Description

[0033] Figure 1 For magnetically imprinted polymers (ReO4) - —Flowchart of the preparation process of MIIPs;

[0034] Figure 2 TEM images of the magnetically imprinted polymer prepared in Example 1, wherein (a) Fe3O4 magnetic nanoparticles, (b) Fe3O4@mSiO2, and (cd) ReO4 - —MIIPs;

[0035] Figure 3 The magnetically imprinted polymer prepared in Example 2 affects ReO4 at different initial concentrations. - Adsorption effect diagram;

[0036] Figure 4The image shows the separation effect of the magnetically imprinted polymer prepared in Example 3 under an applied magnetic field. Detailed Implementation

[0037] The present invention will be described in more detail below with reference to the embodiments. These embodiments are merely descriptions of the best mode of implementation of the present invention and do not limit the scope of the present invention in any way.

[0038] This invention provides a preparation process for a magnetically imprinted polymer for separating perrhenate ions, as follows: Figure 1 As shown. The prepared magnetically imprinted polymer was used for the separation and extraction of perrhenate ions from solutions containing rhenium secondary resources.

[0039] Example 1

[0040] Step (1), Preparation of Fe3O4 magnetic nanoparticles: 1 mol FeCl3·6H2O, 5 mol sodium acetate, and 120 g polyethylene glycol-2000 were added sequentially to 50 mL of ethylene glycol, and the mixture was sonicated for 30 min. The mixture was then transferred to a reaction vessel and heated at 180 °C for 12 h to obtain a black solid product. After the reaction, the product was washed with ethanol and water, and then vacuum dried at 60 °C for 24 h to obtain Fe3O4 magnetic nanoparticles.

[0041] Step (2), Preparation of Fe3O4@mSiO2: The Fe3O4 magnetic nanoparticles prepared in step (1) were dispersed in a mixed solution of 40 mL cyclohexane, 40 mL water and 1.5 mL isopropanol. 1.0 g urea and 1.2 g hexadecyltrimethylammonium bromide were added and stirred for 0.5 h. 1.0 mL tetraethyl orthosilicate was added and the mixture was stirred in an oil bath at 70 °C for 16 h. After the reaction was completed, the mixture was washed with ethanol and water 3-4 times in sequence. The product was separated using an external magnetic field and freeze-dried for 24 h to obtain Fe3O4@mSiO2.

[0042] Step (3), Preparation of Fe3O4@mSiO2@SH: Disperse 0.4g of Fe3O4@mSiO2 obtained in step (2) into ethanol, sonicate for 0.5h, adjust the pH of the solution to 8-10, add 1.0mL of 3-mercaptopropyltrimethoxysilane dropwise, react in a water bath at 35℃ for 10h with stirring, wash with ethanol and water 3-4 times in sequence after the reaction, separate the product using an external magnetic field, freeze dry for 24h to obtain Fe3O4@mSiO2@SH.

[0043] Step (4), ReO4 -Preparation of MIIPs magnetic imprinted polymers: 1 mL of potassium perrhenate (100-200 mg / L) and 5 mmol of N-vinylimidazole were dissolved in an aqueous ethanol solution and sonicated for 0.5 h. 0.1 g of Fe3O4@mSiO2@SH microspheres were added, and the mixture was reacted in a water bath at 45 °C for 12 h with stirring to carry out a prepolymerization reaction. 6 mmol of N,N-methylenebisacrylamide and 1.0 mmol of pentaerythritol tetra-3-mercaptopropylene were added, along with 0.4 g of benzoin dimethyl ether photoinitiator. The mixture was then subjected to ultraviolet light irradiation for 5 h of mercapto-olefin click polymerization. After the reaction, the mixture was washed 3-4 times sequentially with anhydrous ethanol, dilute nitric acid, and deionized water. The resulting product was separated using an external magnetic field and freeze-dried for 24 h to obtain the ReO4. - -MIIPs (Magnetic Imprinted Polymers)

[0044] The magnetically imprinted polymer for separating perrhenate ions prepared in this embodiment has an interpenetrating network structure, and its microstructure is as follows: Figure 2 As shown. The obtained magnetically imprinted polymer was used for the separation and extraction of perrhenate ions from solutions containing rhenium secondary resources.

[0045] Example 2

[0046] Step (1), Preparation of Fe3O4 magnetic nanoparticles: 2 mol FeCl3·6H2O, 7 mol sodium acetate, and 150 g polyethylene glycol-2000 were added sequentially to 50 mL of ethylene glycol, and the mixture was sonicated for 30 min. The mixture was then transferred to a reaction vessel and heated at 200 °C for 12 h to obtain a black solid product. After the reaction, the product was washed with ethanol and water, and then vacuum dried at 60 °C for 24 h to obtain Fe3O4 magnetic nanoparticles.

[0047] Step (2), Preparation of Fe3O4@mSiO2: The Fe3O4 magnetic nanoparticles prepared in step (1) were dispersed in a mixed solution of 50 mL cyclohexane, 50 mL water and 2.0 mL isopropanol. 3.0 g urea and 2.0 g hexadecyltrimethylammonium bromide were added and stirred for 0.5 h. 2.5 mL tetraethyl orthosilicate was added and the mixture was stirred in an oil bath at 65 °C for 16 h. After the reaction was completed, the mixture was washed with ethanol and water 3-4 times in sequence. The product was separated using an external magnetic field and freeze-dried for 24 h to obtain Fe3O4@mSiO2.

[0048] Step (3), Preparation of Fe3O4@mSiO2@SH: Disperse 0.6g of Fe3O4@mSiO2 obtained in step (2) into ethanol, sonicate for 0.5h, adjust the pH of the solution to 8-10, add 1.5mL of 3-mercaptopropyltrimethoxysilane dropwise, react in a water bath at 35℃ for 10h with stirring, wash with ethanol and water 3-4 times in sequence after the reaction, separate the product using an external magnetic field, freeze dry for 24h to obtain Fe3O4@mSiO2@SH.

[0049] Step (4), ReO4 - Preparation of MIIPs magnetic imprinted polymers: 1 mL of potassium perrhenate (100-200 mg / L) and 6 mmol of N-vinylimidazole were dissolved in an aqueous ethanol solution and sonicated for 0.5 h. 0.2 g of Fe3O4@mSiO2@SH microspheres were added, and the mixture was reacted in a water bath at 45 °C for 12 h with stirring to carry out a prepolymerization reaction. 5 mmol of N,N-methylenebisacrylamide and 2.0 mmol of pentaerythritol tetra-3-mercaptopropylene were added, along with 0.5 g of benzoin dimethyl ether photoinitiator. The mixture was then subjected to ultraviolet light irradiation for 5 h of mercapto-olefin click polymerization. After the reaction, the mixture was washed 3-4 times successively with anhydrous ethanol, dilute nitric acid, and deionized water. The resulting product was separated using an external magnetic field and freeze-dried for 24 h to obtain the ReO4. - -MIIPs (Magnetic Imprinted Polymers)

[0050] The magnetically imprinted polymer for separating perrhenate ions prepared in this embodiment has an interpenetrating network structure. The obtained magnetically imprinted polymer is used for the separation and extraction of perrhenate ions from solutions containing rhenium secondary resources.

[0051] Example 3

[0052] Step (1), Preparation of Fe3O4 magnetic nanoparticles: 3 mol FeCl3·6H2O, 8 mol sodium acetate, and 175 g polyethylene glycol-2000 were added sequentially to 50 mL of ethylene glycol, and the mixture was sonicated for 30 min. The mixture was then transferred to a reaction vessel and heated at 200 °C for 12 h to obtain a black solid product. After the reaction, the product was washed with ethanol and water, and then vacuum dried at 60 °C for 24 h to obtain Fe3O4 magnetic nanoparticles.

[0053] Step (2), Preparation of Fe3O4@mSiO2: The Fe3O4 magnetic nanoparticles prepared in step (1) were dispersed in a mixed solution of 65 mL cyclohexane, 65 mL water and 3.5 mL isopropanol. 4.5 g urea and 5.0 g hexadecyltrimethylammonium bromide were added and stirred for 0.5 h. 5.5 mL tetraethyl orthosilicate was added and the mixture was stirred in an oil bath at 65 °C for 16 h. After the reaction was completed, the mixture was washed with ethanol and water 3-4 times in sequence. The product was separated using an external magnetic field and freeze-dried for 24 h to obtain Fe3O4@mSiO2.

[0054] Step (3), Preparation of Fe3O4@mSiO2@SH: Disperse 1.0g of Fe3O4@mSiO2 obtained in step (2) into ethanol, sonicate for 0.5h, adjust the pH of the solution to 8-10, add 0.5mL of 3-mercaptopropyltrimethoxysilane dropwise, react in a water bath at 35℃ for 10h with stirring, wash with ethanol and water 3-4 times in sequence after the reaction, separate the product using an external magnetic field, freeze dry for 24h to obtain Fe3O4@mSiO2@SH.

[0055] Step (4), ReO4 - Preparation of MIIPs magnetic imprinted polymers: 1 mL of potassium perrhenate (100-200 mg / L) and 3 mmol of N-vinylimidazole were dissolved in an aqueous ethanol solution and sonicated for 0.5 h. 0.3 g of Fe3O4@mSiO2@SH microspheres were added, and the mixture was reacted in a water bath at 45 °C for 12 h with stirring to carry out a prepolymerization reaction. 3 mmol of N,N-methylenebisacrylamide and 2.5 mmol of pentaerythritol tetra-3-mercaptopropylene were added, along with 0.4 g of benzoin dimethyl ether photoinitiator. The mixture was then subjected to ultraviolet light irradiation for 5 h of mercapto-olefin click polymerization. After the reaction, the mixture was washed 3-4 times sequentially with anhydrous ethanol, dilute nitric acid, and deionized water. The resulting product was separated using an external magnetic field and freeze-dried for 24 h to obtain the ReO4. - -MIIPs (Magnetic Imprinted Polymers)

[0056] The magnetically imprinted polymer for separating perrhenate ions prepared in this embodiment has an interpenetrating network structure. The obtained magnetically imprinted polymer is used for the separation and extraction of perrhenate ions from solutions containing rhenium secondary resources.

[0057] Example 4

[0058] Weigh 10 mg of ReO4 prepared in Example 1 - - MIIPs particles were loaded into a 20 mL beaker containing a 100 mg / L rhenium secondary resource solution. The beaker was sealed, and the reaction system was placed at room temperature. Samples were taken every 10 minutes, and the adsorption capacity was determined and calculated using ICP-AES. After adsorption was complete, ReO4 was recovered using an external magnetic field.- -MIIPs particles will recover the ReO4 - - MIIPs were placed in a beaker containing 50 mL of ammonia solution and desorbed at room temperature for 8 hours. After desorption, ReO4 was recovered and dried using an external magnetic field. - - MIIPs are easy to use next time. After standing for 15 minutes, their desorption rate is measured and calculated by ICP-AES.

[0059] Table 1. Adsorption selectivity experiment of a magnetically imprinted polymer for separating perrhenate ions.

[0060]

[0061] Example 5

[0062] Weigh 10 mg of ReO4 prepared in Example 2 - - MIIPs particles were loaded into a 25 mL beaker containing a 100 mg / L rhenium secondary resource solution. The beaker was sealed, and the reaction system was placed at room temperature. Samples were taken every 30 minutes, and the adsorption capacity was determined and calculated using ICP-AES. After adsorption was complete, ReO4 was recovered using an external magnetic field. - -MIIPs particles will recover the ReO4 - - MIIPs were placed in a beaker containing 50 mL of ammonia solution and desorbed at room temperature for 10 h. After desorption, ReO4 was recovered and dried using an external magnetic field. - - MIIPs are easy to use next time. After standing for 15 minutes, their desorption rate is measured and calculated by ICP-AES.

[0063] Table 2. Adsorption selectivity experiments of a magnetically imprinted polymer for separating perrhenate ions.

[0064]

[0065] Example 6

[0066] Weigh 20 mg of ReO4 prepared in Example 3 - - MIIPs particles were loaded into a 20 mL beaker containing a 100 mg / L rhenium secondary resource solution. The beaker was sealed, and the reaction system was placed at room temperature. Samples were taken every 60 minutes, and the adsorption capacity was determined and calculated using ICP-AES. After adsorption was complete, ReO4 was recovered using an external magnetic field. - -MIIPs particles will recover the ReO4 - - MIIPs were placed in a beaker containing 50 mL of ammonia solution and desorbed at room temperature for 12 h. After desorption, ReO4 was recovered and dried using an external magnetic field. -- MIIPs are easy to use next time. After standing for 15 minutes, their desorption rate is measured and calculated by ICP-AES.

[0067] Table 3. Adsorption selectivity experiments of a magnetically imprinted polymer for separating perrhenate ions.

[0068]

[0069] As can be seen from Examples 4-6 above, the magnetically imprinted polymer with perrhenate ions has a positive effect on ReO4 in solutions containing rhenium secondary resources. - It possesses extremely strong adsorption capacity and high desorption rate, enabling precise and rapid separation of ReO4 from complex multi-element rhenium-containing secondary resource solutions. - The goal.

[0070] The advantages of this invention overcome the shortcomings of traditional adsorption materials, such as low adsorption capacity, poor selectivity, low desorption rate, limited reusability, and difficulty in recovering powdered adsorbents, thus achieving directional and efficient separation of ReO4. - The invention aims to achieve its intended goals and possesses significant engineering and economic value. The principle of this invention is as follows:

[0071] Ion imprinting (IIT), a highly efficient method for metal ion recognition, relies on using target metal ions as templates. It leverages coordinating or chelating groups on functional monomers to specifically recognize these template ions, and then uses cross-linking agents to fix the recognition sites, forming a structurally stable polymer network. After eluting away the template ions, the polymer is left with numerous imprinted cavities that highly match the template ions in terms of spatial size, geometry, and chemical environment, thus giving the ion-imprinted material excellent selective adsorption capabilities.

[0072] To enhance the recyclability and ease of operation of ion-imprinted materials in practical applications, they are combined with magnetic carriers. By introducing Fe3O4 magnetic nanoparticles, magnetic ion-imprinted polymers (MIIPs) with both highly selective adsorption and rapid magnetic separation functions can be constructed. These materials not only retain their specific recognition performance for target ions but also enable efficient recovery and regeneration of the adsorbent using an external magnetic field, significantly improving the material's practical value and recycling efficiency.

Claims

1. A method for preparing a magnetically imprinted polymer for separating perrhenate ions, characterized in that: Fe3O4@mSiO2 was prepared by coating Fe3O4 magnetic nanoparticles with a layer of mesoporous SiO2 using tetraethyl orthosilicate as the silicon source. Fe3O4@mSiO2@SH microspheres were then prepared by thiol modification with 3-mercaptopropyltrimethoxysilane. Perrhenate ions were used as template ions, N-vinylimidazolium as the functional monomer, N'N-methylenebisacrylamide and pentaerythritol tetra-3-mercaptopropylene as crosslinking agents, benzoin dimethyl ether as a photoinitiator, and a water-ethanol mixture as a pore-forming agent. A thiol-olefin click polymerization method was then used to prepare a magnetically imprinted polymer that separates perrhenate ions. The specific steps include: Step (1) Preparation of Fe3O4 magnetic nanoparticles: FeCl3·6H2O, sodium acetate and polyethylene glycol-2000 were added to ethylene glycol in sequence, ultrasonically treated for 30-50 min, transferred to a reaction vessel and heated at 180-200℃ for 12-18 h to obtain a black solid product. After the reaction was completed, the product was washed with ethanol and water and vacuum dried at 60℃ for 24 h to obtain Fe3O4 magnetic nanoparticles. Step (2), Preparation of Fe3O4@mSiO2: The Fe3O4 magnetic nanoparticles prepared in step (1) are dispersed in a mixed solution of cyclohexane, water and isopropanol. Urea and hexadecyltrimethylammonium bromide are added, and the mixture is stirred for 0.5-1 h. Tetraethyl orthosilicate is added, and the mixture is reacted in an oil bath at 60-90℃ for 15-20 h. After the reaction is completed, the mixture is washed with ethanol and water 3-4 times in sequence. The product is separated using an external magnetic field and freeze-dried for 12-24 h to obtain Fe3O4@mSiO2. Step (3), Preparation of Fe3O4@mSiO2@SH: Disperse the Fe3O4@mSiO2 obtained in step (2) into ethanol, sonicate for 0.5-1h, adjust the pH of the solution to 8-10, add 3-mercaptopropyltrimethoxysilane dropwise, react in a water bath at 35-40℃ for 10-15h with stirring, wash with ethanol and water 3-4 times in sequence after the reaction, separate the product using an external magnetic field, freeze dry for 12-24h to obtain Fe3O4@mSiO2@SH; Step (4), ReO4 - Preparation of MIIPs magnetic imprinted polymer: 1 mL of potassium perrhenate (100-200 mg / L) and N-vinylimidazole were dissolved in an aqueous ethanol solution and sonicated for 0.5-1 h. 0.1-0.3 g of Fe3O4@mSiO2@SH microspheres were added, and the mixture was reacted in a water bath at 45-50 °C with stirring for 10-15 h for prepolymerization. N'N-methylenebisacrylamide and pentaerythritol tetra-3-mercaptopropylene were added, along with 0.3-0.6 g of benzoin dimethyl ether photoinitiator. The mixture was subjected to thiol-olefin click polymerization under ultraviolet light for 3-5 h. After the reaction, the mixture was washed 3-4 times with anhydrous ethanol, dilute nitric acid, and deionized water. The product was separated using an external magnetic field and freeze-dried for 12-24 h to obtain the magnetic imprinted polymer.

2. The method according to claim 1, characterized in that, In step (1), the ratio of FeCl3·6H2O, sodium acetate and polyethylene glycol-2000 is 1~3 mol: 5~8 mol: 100~180 g.

3. The method according to claim 1, characterized in that, In step (2), the volume ratio of the mixed solution of cyclohexane, water and isopropanol is 30~100mL:30~100mL:1~3mL.

4. The method according to claim 1, characterized in that, In step (2), the ratio of urea, hexadecyltrimethylammonium bromide and tetraethyl orthosilicate is 1~5g: 1~5g: 1~10mL.

5. The method according to claim 1, characterized in that, In step (3), the ratio of Fe3O4@mSiO2 to 3-mercaptopropyltrimethoxysilane is 0.2~1g:0.3~1.5mL.

6. The method according to claim 1, characterized in that, In step (4), the ratio of potassium perrhenate, N-vinylimidazole, N,N-methylenebisacrylamide, and pentaerythritol tetra-3-mercaptopropylene is 1 mL: 3~6 mmol: 2~6 mmol: 1~3 mmol.

7. A magnetically imprinted polymer prepared by the method according to any one of claims 1 to 6.

8. The magnetically imprinted polymer according to claim 7, characterized in that: The magnetically imprinted polymer can be used to separate perrhenate ions from rhenium-containing secondary resource solutions. The specific steps are as follows: (a) Adsorption performance of magnetically imprinted polymer: 5-50 mg of magnetically imprinted polymer particles were added to 10-60 mL of rhenium-containing secondary resource solution to form a reaction system. The reaction system was placed under closed and room temperature conditions for adsorption. The adsorption time was 5-120 min. (b) Desorption performance of magnetically imprinted polymer: The magnetically imprinted polymer particles after the adsorption in step (a) are separated by an external magnetic field and then placed in an ammonia solution for desorption at a constant temperature for 3-12 hours. After desorption, the magnetically imprinted polymer is recovered by an external magnetic field and recycled.

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