Magnesium ion imprinted polymer as well as preparation method and application thereof

Abstract

The invention discloses a magnesium ion imprinted polymer and a preparation method and application thereof.The preparation method comprises the following steps that soluble magnesium salt and methyl alcohol are evenly mixed, 8-hydroxyquinoline is added into the mixture, stirring is conducted, magnesium ions and 8-hydroxyquinoline are fully complexed, methacrylic acid is added into the mixture, stirring is conducted for a set time, and a mixed solution is obtained; adding ethylene glycol dimethacrylate into the mixed solution, stirring for a set time, introducing inert gas into the solution, emptying air in the solution, adding azodiisobutyronitrile into the solution, and stirring at 55-65 DEG C to obtain a polymer; and separating and washing the polymer, eluting with an EDTA (Ethylene Diamine Tetraacetic Acid) solution, washing with ethanol and water until the solution is neutral, and drying to obtain the product. The magnesium ion imprinted polymer prepared by the invention can be repeatedly used for multiple times, and the adsorption performance after regeneration is still very stable.

Description

Technical Field

[0001] The invention belongs to the technical field of ion imprinted material adsorption and separation, and specifically relates to a magnesium ion imprinted polymer and a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Magnesium is an element with a large amount of existence. The concentration of magnesium ions is of great significance in different fields such as 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 will cause many industrial problems such as scaling and corrosion. Especially in the field of circulating cooling water, circulating cooling water will be continuously concentrated during use. The ion concentration in the concentrated water is very high and needs to be treated before it can be discharged, which will increase operating costs and easily cause secondary pollution.

[0004] Ion imprinting technology is an adsorbent preparation technology developed in the past two decades based on molecular imprinting technology. The adsorbent prepared by ion imprinting technology has the advantages of large adsorption capacity and selectivity, and can be desorbed and regenerated, and can still maintain fairly stable performance after repeated use. However, the preparation of ion imprinted polymers requires pure organic reagents as solvents and is synthesized under heating reaction conditions. The yield is low, and the recognition site is deeply embedded, resulting in problems such as difficulty in elution of imprinted polymers. Moreover, the current synthesis technology of ion imprinted polymers is difficult to operate and not easy to achieve. Therefore, based on the above reasons, ion imprinting technology is difficult to be applied in practice. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a magnesium ion imprinted polymer and a preparation method and application thereof, and to demonstrate the feasibility of ion imprinted polymer in the field of treating circulating cooling water.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

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

[0008] Mix the soluble magnesium salt and methanol, add 8-hydroxyquinoline (ligand) thereto, stir to allow the magnesium ions to fully complex with 8-hydroxyquinoline, then add methacrylic acid (functional monomer) thereto, and stir for a set time to obtain a mixed solution;

[0009] Add ethylene glycol dimethacrylate (crosslinking agent) to the mixed solution, stir for a set time, introduce inert gas into the solution to exhaust the air in the solution, add azobisisobutyronitrile (initiator) to the solution, stir at 55-65° C. to obtain a polymer;

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

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

[0012] The polymer is separated and washed. Since the nitrogen atom of the adsorbent with 8-hydroxyquinoline as a ligand is very easy to be protonated under acidic conditions, a weakly acidic (pH 6) EDTA solution is used for elution, and then the EDTA is 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 the 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 stirring time at 25-35° C. is 0.5-1.5 h.

[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 h.

[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] In a second aspect, the present invention provides a magnesium ion imprinted polymer prepared by the preparation method.

[0023] In a third aspect, the present invention provides use of the magnesium ion imprinted polymer in a magnesium ion adsorbent.

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

[0025] The invention prepares the magnesium ion imprinted polymer by adopting the ion imprinting technology. The particle size of the material is not at the nanometer level, the material has an objective adsorption capacity for magnesium ions, and the adsorbent is easy to recover.

[0026] The magnesium ion imprinted polymer prepared by the present invention can be reused many times, and the adsorption performance after regeneration is still very stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 This is the SEM electron micrograph of magnesium ion imprinted polymer;

[0029] Figure 2 FTIR spectra of magnesium ion imprinted polymer before and after adsorption and non-ionic imprinted polymer. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] The present invention will be further described below in conjunction with the embodiments.

[0032] Example 1

[0033] Preparation and characterization of magnesium ion imprinted polymer:

[0034] Step 1, place 1 mmoL of magnesium nitrate hexahydrate and 100 mL of methanol in a 250 mL round-bottom flask and mix thoroughly;

[0035] Step 2: Add 2 mmol of ligand to the solution in step 1, and stir at room temperature for 2 hours to allow the magnesium ion and the ligand to fully complex: the ligand is 8-hydroxyquinoline;

[0036] Step 3, adding 2 mmol of the functional monomer to the solution obtained in step 2, and stirring at room temperature for 1 hour to allow the functional monomer to fully combine with the existing magnesium-ligand system, wherein the functional monomer is methacrylic acid;

[0037] Step 4: Add 8 mmol of a cross-linking agent to the solution obtained in step 3, stir at room temperature for 1 hour, and then use argon gas to aerate for 20 minutes to exhaust the air in the container: the cross-linking agent is ethylene glycol dimethacrylate;

[0038] Step 5, adding 50 mg of azobisisobutyronitrile to the solution obtained in step 4, stirring at a low speed with a magnetic force at a temperature of 60° C. for 24 hours, and the formed polymer precipitates to the bottom of the container;

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

[0040] The obtained magnesium ion imprinted polymer was subjected to FTIR spectrum scanning and SEM electron microscope scanning. The results are as follows Figure 1 shown.

[0041] The results of SEM scanning electron microscope showed that the magnesium ion imprinted polymer prepared by precipitation polymerization was a very regular nano-microsphere. Figure 2 As shown in the figure, the results of FTIR spectrum scanning show that in all polymers, -1 A strong carbonyl C=O stretching band was observed at 1637 cm -1 The C=C variable olefin stretching band was observed at 1450 cm -1 A strong NH amide stretching band was observed at 1153 cm -1 A strong CO stretching band is observed at a wave number of .

[0042] Comparative Example 1

[0043] Step 1, place 100 mL of methanol in a 250 mL round-bottom flask;

[0044] Step 2: Add 2 mmol of a ligand to the solution in step 1 and stir at room temperature for 2 h: the ligand is 8-hydroxyquinoline;

[0045] Step 3, adding 2 mmol of the functional monomer to the solution obtained in step 2, and stirring at room temperature for 1 hour to allow the functional monomer to fully combine with the existing ligand, wherein the functional monomer is methacrylic acid;

[0046] Step 4: Add 8 mmol of a cross-linking agent to the solution obtained in step 3, stir at room temperature for 1 hour, and then use argon gas to aerate for 20 minutes to exhaust the air in the container: the cross-linking agent is ethylene glycol dimethacrylate;

[0047] Step 5, adding 50 mg of azobisisobutyronitrile to the solution obtained in step 4, stirring at a low speed with a magnetic force at a temperature of 60° C. for 24 hours, and the formed polymer precipitates to the bottom of the container;

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

[0049] Maximum adsorption capacity test of the magnesium ion imprinted polymer prepared in Example 1 and the nonionic imprinted polymer prepared in Comparative Example 1:

[0050] 100 mg of magnesium ion imprinted polymer and non-ionic imprinted polymer were accurately weighed by a high-precision electronic balance and placed in 50 mL centrifuge tubes respectively. 30 mL of a magnesium ion solution with a concentration of 10 mg / L was added in sequence. The adsorbed solution was filtered through a 0.45 μm filter membrane. The concentration of magnesium ions in the filtrate was detected by a full-spectrum direct-reading inductively coupled plasma 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-ionic imprinted polymer prepared in Comparative Example 1 was 1.8 mg / g.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a magnesium ion imprinted polymer, characterized in that: The steps include: Mix the soluble magnesium salt and methanol, add 8-hydroxyquinoline thereto, stir to allow the magnesium ions to fully complex with the 8-hydroxyquinoline, then add methacrylic acid thereto, stir for a set time, and obtain a mixed solution; Add ethylene glycol dimethacrylate to the mixed solution, stir for a set time, introduce inert gas into the solution to exhaust the air in the solution, add azobisisobutyronitrile to the solution, stir at 55-65° C. to obtain a polymer; The polymer is separated and washed, then eluted with an EDTA solution, and finally washed with ethanol and water until neutral, and dried to obtain the product.

2. The method for preparing a magnesium ion imprinted polymer according to claim 1, wherein: The soluble magnesium salt is magnesium nitrate.

3. The method for preparing the magnesium ion imprinted polymer according to claim 1, characterized in that: The molar ratio of the soluble magnesium salt, 8-hydroxyquinoline, methacrylic acid and ethylene glycol dimethacrylate is 1:1.5-2.5:1.5-2.5:6-10.

4. The method for preparing the magnesium ion imprinted polymer according to claim 1, characterized in that: After adding 8-hydroxyquinoline, the stirring time at 25-35°C is 1.5-2.5 h.

5. The method for preparing the magnesium ion imprinted polymer according to claim 1, characterized in that: After adding methacrylic acid, the stirring time at 25-35°C is 0.5-1.5 h.

6. The method for preparing the magnesium ion imprinted polymer according to claim 1, characterized in that: After adding ethylene glycol dimethacrylate, stir at 25-35°C for 0.5-1.5h; Alternatively, azobisisobutyronitrile is added to the solution and stirred at 55-65° C. for 20-30 hours.

7. The method for preparing the magnesium ion imprinted polymer according to claim 1, characterized in that: The polymer is eluted with EDTA solution 2-4 times, and the eluent is replaced every 10-14 hours; Preferably, the concentration of the EDTA solution is 0.05-0.15M.

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

9. A magnesium ion imprinted polymer, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the magnesium ion imprinted polymer according to claim 9 in a magnesium ion adsorbent.

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