A magnesium ion imprinted polymer and a preparation method and application thereof

Abstract

The application discloses a magnesium ion imprinted polymer and a preparation method and application thereof. The preparation method comprises the following steps: uniformly mixing a soluble magnesium salt and methanol, adding 8-hydroxyquinoline into the mixture, stirring, fully complexing magnesium ions with the 8-hydroxyquinoline, then adding methacrylic acid into the mixture and stirring for a set time to obtain a mixed solution; adding ethylene glycol dimethacrylate into the mixed solution, stirring for a set time, then introducing inert gas into the solution to remove air in the solution, adding azobisisobutyronitrile into the solution, stirring at 55-65 DEG C to obtain a polymer; separating and washing the polymer, eluting the polymer with an EDTA solution, finally washing the polymer with ethanol and water until the polymer is neutral, and drying the polymer, so that the magnesium ion imprinted polymer is obtained. The magnesium ion imprinted polymer prepared by the application can be repeatedly used, and the adsorption performance of the regenerated magnesium ion imprinted polymer is still very stable.

Description

Technical Field

[0001] This invention belongs to the field of ion-imprinted material adsorption and separation technology, specifically relating to a magnesium ion-imprinted polymer and its preparation method and application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Magnesium is an element found in large quantities, and its ion concentration is crucial in various fields, including industrial and domestic water hardness control, food quality assessment, and medical diagnosis. When the calcium and magnesium content in water exceeds a certain level, it can lead to numerous industrial problems such as scaling and corrosion. This is especially true in the field of circulating cooling water, where the water is continuously concentrated during use, resulting in high ion concentrations that require treatment before discharge. This increases operating costs and can easily cause secondary pollution.

[0004] Ion imprinting is an adsorbent preparation technique developed over the past two decades based on molecular imprinting. Adsorbents prepared using ion imprinting have advantages such as large adsorption capacity, selectivity, and the ability to desorb and regenerate, maintaining relatively stable performance even after repeated use. However, the preparation of ion-imprinted polymers requires pure organic reagents as solvents and is synthesized under heating conditions. Furthermore, the yield is low, and the recognition sites are deeply embedded, often leading to problems such as difficulty in elution. Moreover, the current synthesis techniques for ion-imprinted polymers are complex and difficult to implement. Therefore, for these reasons, ion imprinting technology is rarely applied in practice. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a magnesium ion-imprinted polymer, its preparation method, and its application, demonstrating the feasibility of ion-imprinted polymers in the treatment of circulating cooling water.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a magnesium ion-imprinted polymer, comprising the following steps:

[0008] Soluble magnesium salt and methanol are mixed, 8-hydroxyquinoline (ligand) is added, and the mixture is stirred to allow magnesium ions to fully complex with 8-hydroxyquinoline. Then methacrylic acid (functional monomer) is added and the mixture is stirred for a set time to obtain a mixed solution.

[0009] Ethylene glycol dimethacrylate (crosslinking agent) is added to the mixed solution. After stirring for a set time, an inert gas is introduced into the solution to purge the air. Azobisisobutyronitrile (initiator) is then added to the solution, and the mixture is stirred at 55-65°C to obtain the polymer.

[0010] The polymer is separated, washed, eluted with EDTA solution, washed with ethanol and water until neutral, and dried to obtain the final product.

[0011] Because methacrylic acid (functional monomer) cannot effectively chelate with magnesium ions, and if functional monomers are used directly to chelate metal ions, the selectivity and adsorption capacity of the product will be weakened to some extent, 8-hydroxyquinoline is added to specifically capture free magnesium ions in the solution. The nitrogen and oxygen atoms contained in two molecules of 8-hydroxyquinoline can provide the lone pair electrons required for chelation of a magnesium ion, thereby forming a three-dimensional framework. Therefore, under stirring conditions, magnesium ions are fully chelated with 8-hydroxyquinoline.

[0012] The polymer was separated and washed. Since the nitrogen atoms in the adsorbent with 8-hydroxyquinoline as the ligand are very easily protonated under acidic conditions, a weakly acidic EDTA solution (pH 6) was used for elution. Then, EDTA was washed away with ethanol and finally washed with water until neutral.

[0013] In some embodiments, the soluble magnesium salt is magnesium nitrate.

[0014] In some embodiments, the molar ratio of soluble magnesium salt, 8-hydroxyquinoline, methacrylic acid and ethylene glycol dimethacrylate is 1:1.5-2.5:1.5-2.5:6-10.

[0015] In some embodiments, after adding 8-hydroxyquinoline, the stirring time at 25-35°C is 1.5-2.5 h.

[0016] In some embodiments, after adding methacrylic acid, the mixture is stirred at 25-35°C for 0.5-1.5 hours.

[0017] In some embodiments, after adding ethylene glycol dimethacrylate, the stirring time at 25-35°C is 0.5-1.5 h.

[0018] In some embodiments, after adding azobisisobutyronitrile to the solution, the mixture is stirred at 55-65°C for 20-30 hours.

[0019] In some embodiments, the polymer is eluted with EDTA solution 2-4 times, and the eluent is replaced every 10-14 hours.

[0020] Preferably, the concentration of the EDTA solution is 0.05-0.15M.

[0021] In some embodiments, the drying is vacuum drying, and the drying temperature is 55-65°C.

[0022] Secondly, the present invention provides a magnesium ion imprinted polymer prepared by the aforementioned preparation method.

[0023] Thirdly, the present invention provides the application of the magnesium ion imprinted polymer in magnesium ion adsorbents.

[0024] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0025] This invention prepares magnesium ion-imprinted polymers using ion imprinting technology. The material has a particle size at the nanometer level, exhibits an objective adsorption capacity for magnesium ions, and the adsorbent is easy to recover.

[0026] The magnesium ion imprinted polymer prepared by this invention can be reused multiple times, and its adsorption performance remains very stable after regeneration. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 SEM image of magnesium ion-imprinted polymer;

[0029] Figure 2 The images show the FTIR spectra of the magnesium ion-imprinted polymer before and after adsorption, and the non-ion-imprinted polymer. Detailed Implementation

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] The present invention will be further described below with reference to the embodiments.

[0032] Example 1

[0033] Preparation and characterization of magnesium ion-imprinted polymers:

[0034] Step 1: Place 1 mmol magnesium nitrate hexahydrate and 100 mL methanol in a 250 mL round-bottom flask and mix thoroughly.

[0035] Step 2: Add 2 mmol of the ligand to the solution in Step 1 and stir at room temperature for 2 hours to allow magnesium ions to fully complex with the ligand. The ligand is 8-hydroxyquinoline.

[0036] Step 3: Add 2 mmol of the functional monomer to the solution obtained in Step 2 and stir at room temperature for 1 h to allow the functional monomer to fully combine with the existing magnesium-ligand system. The functional monomer is methacrylic acid.

[0037] Step 4: Add 8 mmol of crosslinking agent to the solution obtained in step 3, stir at room temperature for 1 hour, and then use argon gas to strongly aerate for 20 minutes to remove the air from the container. The crosslinking agent is ethylene glycol dimethacrylate.

[0038] Step 5: Add 50 mg of azobisisobutyronitrile to the solution obtained in step 4, and stir magnetically at low speed for 24 h at 60 °C. The resulting polymer will settle to the bottom of the container.

[0039] The solids obtained in steps 6 and 5 were washed twice with deionized water and ethanol, respectively, and then eluted three times with 0.1M EDTA solution, with the eluent changed every 12 hours. The solids were then washed with anhydrous ethanol and deionized water until neutral, and then vacuum-dried at 60°C for 24 hours to obtain the magnesium ion-imprinted polymer.

[0040] The obtained magnesium ion-imprinted polymer was subjected to FTIR spectroscopy and SEM scanning, and the results are as follows: Figure 1 As shown.

[0041] SEM (Scanning Electron Microscopy) results showed that the magnesium ion-imprinted polymer prepared by precipitation polymerization consisted of highly regular nanospheres. Figure 2 As shown, the FTIR energy dispersive spectroscopy results indicate that, among all polymers, at 1730 cm⁻¹... -1 A strong carbonyl C=O stretching band was observed at the wavenumber of 1637 cm⁻¹. -1 C=C variable olefin stretching bands were observed at 1450 cm. -1 NH strong amide stretching bands were observed at 1153 cm⁻¹. This is because the monomers in the polymer structure contain -COOH groups, resulting in stretching bands at this location. -1 A strong stretching band of CO was observed at the wavenumber.

[0042] Comparative Example 1

[0043] Step 1: Place 100 mL of methanol into a 250 mL round-bottom flask;

[0044] Step 2: Add 2 mmol / L of the ligand to the solution in Step 1 and stir at room temperature for 2 hours; the ligand is 8-hydroxyquinoline.

[0045] Step 3: Add 2 mmol of the functional monomer to the solution obtained in Step 2 and stir at room temperature for 1 hour to allow the functional monomer to fully combine with the existing ligand. The functional monomer is methacrylic acid.

[0046] Step 4: Add 8 mmol of crosslinking agent to the solution obtained in step 3, stir at room temperature for 1 hour, and then use argon gas to strongly aerate for 20 minutes to remove the air from the container. The crosslinking agent is ethylene glycol dimethacrylate.

[0047] Step 5: Add 50 mg of azobisisobutyronitrile to the solution obtained in step 4, and stir magnetically at low speed for 24 h at 60 °C. The resulting polymer will settle to the bottom of the container.

[0048] The solids obtained in steps 6 and 5 were washed twice with deionized water and ethanol, respectively, and then eluted three times with 0.1M EDTA solution, with the eluent changed every 12 hours. The solids were then washed with anhydrous ethanol and deionized water until neutral, and then vacuum-dried at 60°C for 24 hours to obtain the nonionic imprinted polymer.

[0049] Maximum adsorption capacity tests of the magnesium ion-imprinted polymer prepared in Example 1 and the non-ion-imprinted polymer prepared in Comparative Example 1:

[0050] 100 mg of magnesium ion-imprinted polymer and non-ion-imprinted polymer were accurately weighed using a high-precision electronic balance and placed into 50 mL centrifuge tubes respectively. 30 mL of magnesium ion solution with a concentration of 10 mg / L was added sequentially. The adsorption solution was filtered through a 0.45 μm filter membrane, and the concentration of magnesium ions in the filtrate was detected using a full-spectrum direct-reading inductively coupled plasma atomic emission spectrometer. The adsorption capacity of the magnesium ion-imprinted polymer was calculated. The results showed that the maximum adsorption capacity of the magnesium ion-imprinted polymer prepared in Example 1 was 3.1 mg / g, and the adsorption capacity of the non-ion-imprinted polymer prepared in Comparative Example 1 was 1.8 mg / g.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium ion-imprinted polymer, characterized in that: The steps include the following: Magnesium nitrate and methanol were mixed, 8-hydroxyquinoline was added, and the mixture was stirred to allow magnesium ions to fully complex with 8-hydroxyquinoline. Then methacrylic acid was added and the mixture was stirred for a set time to obtain a mixed solution. Ethylene glycol dimethacrylate was added to the mixed solution, and after stirring for a set time, an inert gas was introduced into the solution to purge the air from the solution. Azobisisobutyronitrile was then added to the solution, and the mixture was stirred at 55-65°C to obtain the polymer. The polymer is separated, washed, eluted with EDTA solution at pH 6, and finally washed with ethanol and water until neutral, and dried to obtain the final product. The polymer is eluted with EDTA solution 2-4 times, and the eluent is changed every 10-14 hours. The molar ratio of soluble magnesium salt, 8-hydroxyquinoline, methacrylic acid and ethylene glycol dimethacrylate is 1:1.5-2.5:1.5-2.5:6-10; After adding 8-hydroxyquinoline, stir at 25-35℃ for 1.5-2.5 hours. After adding methacrylic acid, stir at 25-35℃ for 0.5-1.5 hours. After adding ethylene glycol dimethacrylate, stir at 25-35℃ for 0.5-1.5 hours.

2. The method for preparing the magnesium ion-imprinted polymer according to claim 1, characterized in that: After adding azobisisobutyronitrile to the solution, stir at 55-65℃ for 20-30 hours.

3. The method for preparing the magnesium ion-imprinted polymer according to claim 1, characterized in that: The concentration of the EDTA solution is 0.05-0.15M.

4. The method for preparing the magnesium ion-imprinted polymer according to claim 1, characterized in that: The drying process is vacuum drying, and the drying temperature is 55-65℃.

5. A magnesium ion-imprinted polymer, characterized in that: It is prepared by any one of the preparation methods described in claims 1-4.

6. The application of the magnesium ion imprinted polymer of claim 5 in magnesium ion adsorbents.

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