Foam adsorbent and application thereof in ReO4 <-> adsorption

Abstract

The invention discloses a foam adsorbent, which comprises a polyurethane foam matrix, a polyion liquid shown in the following structural formula and # imgabs0 # are dispersed in the polyurethane foam matrix, A <-> is bis (trifluoromethylsulfonyl) imide anion or halide ion, mgt, and B <-> is bis (trifluoromethylsulfonyl) imide anion or halide ion. 0, ngt; 0. Compared with a polyion liquid only containing a 1-vinyl-3-cyanomethylimidazole or 1-[(4-vinylphenyl) methyl]-1-methylpiperidine monomer structural unit, the polyion liquid disclosed by the invention has more excellent adsorption performance on ReO4 <-> and is simple in preparation process; and about 70% of the original adsorption performance of the polyion liquid can be achieved only by 4wt% of loading capacity, so that the polyion liquid has extremely high cost performance.

Description

Technical Field

[0001] The present invention belongs to the field of adsorbents, and particularly relates to a foam adsorbent for adsorbing ReO4 - . Background Art

[0002] Technetium-99 ( 99 Tc) is a long-lived fission product with a half-life of up to 2.13×10 5 years. It usually exists in the form of TcO4 - in water, has high solubility and migration ability, and is one of the most important nuclides in the long-term disposal of radioactive waste and environmental safety assessment. Since there is no naturally stable isotope of technetium and it is difficult to operate in a conventional laboratory, and rhenium (Re) has a similar radius and geochemical behavior to technetium, ReO4 - is usually used as a substitute to simulate the removal of TcO4 - in nuclear waste liquid.

[0003] Adsorbent materials have the advantages of simple operation, recyclability, and no secondary pollution, and are widely used for the separation of harmful substances in wastewater. CN110732306A discloses a modified covalent organic framework material for adsorbing and separating rhenium and its preparation method, which grafts 1-vinyl-3-ethylimidazolium bromide into the pores of the covalent organic framework material by a radiation method. CN114783641A discloses an application method of a polyionic liquid gel material in uranium-rhenium adsorption and separation, which uses 1-vinyl-3-ethylimidazolium bromide as a monomer and 1-allyl-3-vinylimidazolium bromide as a cross-linking agent to obtain a polyionic liquid gel by a radiation method. Although the above two adsorbent materials have good adsorption performance for rhenium, the preparation process requires the use of a radiation source, which is highly dangerous. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a foam adsorbent, which has excellent adsorption ability for ReO4 - and the preparation process is simple and easy to operate.

[0005] To achieve the above purpose, the present invention adopts the following technical scheme: A foam adsorbent, comprising a polyurethane foam matrix, and polyionic liquid shown by the following structural formula is dispersed in the polyurethane foam matrix,

[0006] A - is bistrifluoromethylsulfonylimide anion or halide ion, m>0, n>0.

[0007] Preferably, the ratio of m to n is 1:1 to 1:10, and more preferably the ratio of m to n is 1:2.

[0008] Preferably, the number average molecular weight of the polyionic liquid is 4000 to 8000.

[0009] Preferably, the content of the polyionic liquid is 1 to 20 wt% of the polyurethane foam matrix.

[0010] More preferably, the content of the polyionic liquid is 4 to 10 wt% of the polyurethane foam matrix.

[0011] The preparation method of the above-mentioned foam adsorbent includes: mixing the polyionic liquid and aqueous polyurethane in water and stirring until foaming is complete, and then freeze-drying to obtain the foam adsorbent.

[0012] The application of the above-mentioned foam adsorbent in adsorbing ReO4 - and / or TcO4 - .

[0013] The preparation method of the above-mentioned polyionic liquid includes: Mixing 1-vinyl-3-cyanomethylimidazole bromide, 1-[(4-vinylphenyl)methyl]-1-methylpiperidinium bromide and an initiator in a solvent, heating and polymerizing to obtain a polyionic liquid.

[0014] Preferably, the molar ratio of 1-vinyl-3-cyanomethylimidazole bromide to 1-[(4-vinylphenyl)methyl]-1-methylpiperidinium bromide is 1:1 to 1:10, and more preferably 1:2.

[0015] Preferably, the initiator is azobisisobutyronitrile, and the dosage is 0.1 to 1 wt% of the monomer.

[0016] Preferably, the temperature of the polymerization reaction is 20 to 60 °C.

[0017] Preferably, the solvent in step (1) is dimethyl sulfoxide.

[0018] Compared with the fact that halide ions such as bromine cause certain pollution to water bodies, the halide ions of the polyionic liquid can be replaced with more environmentally friendly bis(trifluoromethylsulfonyl)imide anions by an ion exchange method.

[0019] The application of the above-mentioned polyionic liquid in adsorbing ReO4 - and / or TcO4 - .

[0020] Beneficial effects Compared with the poly(ionic liquid) containing only the structural units of 1-vinyl-3-cyanomethylimidazole or 1-[(4-vinylphenyl)methyl]-1-methylpiperidine monomers, the poly(ionic liquid) of the present invention has better adsorption performance for ReO4 - and has a simple preparation process.

[0021] After the poly(ionic liquid) of the present invention is loaded on polyurethane foam, a loading amount of only 4 wt% can reach about 70% of the original adsorption performance of the poly(ionic liquid), having extremely high cost performance. Detailed Description of the Invention

[0022] The technical solutions of the present invention will be further described in detail below in conjunction with the embodiments.

[0023] Example 1 The synthesis reaction of the poly(ionic liquid) of the present invention is as follows:

[0024] After mixing 1-vinyl-3-cyanomethylimidazole bromide (1.0 mol) and 1-[(4-vinylphenyl)methyl]-1-methylpiperidine bromide (2.0 mol, CAS: 84555-04-4), 0.2 wt% (total amount of monomers) of the initiator azobisisobutyronitrile (AIBN) and an appropriate amount of dimethyl sulfoxide (DMSO) solvent are added, and the mixture is charged into a round-bottom flask. Under a N2 atmosphere, the reaction is carried out at 30 °C for 24 h. When cooled to room temperature, the reactants are added dropwise to tetrahydrofuran (THF), and the precipitated PIL precipitate is washed with ethanol and then vacuum-dried at 60 °C for 12 h. Then the dried PIL is dispersed in deionized water, stirred until completely dissolved, and then an aqueous solution of lithium bis(trifluoromethanesulfonyl)imide (LiTf2N, 3.0 mol) is slowly added. After stirring for 2 hours, the precipitate is washed with deionized water and vacuum-dried at 70 °C for 12 h to obtain MPIL.

[0025] A certain amount of MPIL and waterborne polyurethane (WPU) are added to an appropriate amount of deionized water, and a homogenizer (4×10 4 rpm) is used to stir vigorously for 10 min until complete foaming, and then freeze-dried to obtain a foam adsorbent (WPU / MPIL) with an MPIL content of 10 wt%.

[0026] Comparative Examples 1-2 The specific preparation processes of the comparative samples WPU / MPIL-DB-1 and WPU / MPIL-DB-2 are the same as those of Example 1, with the only difference being that 1-vinyl-3-cyanomethylimidazolium bromide and 1-[(4-vinylphenyl)methyl]-1-methylpiperidinium bromide are separately used as monomers when preparing MPIL-DB-1 and MPIL-DB-2. The synthesis reactions of MPIL-DB-1 and MPIL-DB-2 are as follows:

[0027] Blank control sample: A certain amount of WPU was added to deionized water, and it was vigorously stirred with a homogenizer (4×10 4 rpm) for 10 min until complete foaming occurred, and then freeze-dried to obtain the foam adsorbent (PU-0).

[0028] Performance test of the foam adsorbent: 20 mg of the adsorbent to be tested was added to a conical flask containing 20 mL of 50 mg·L -1 ReO4 - solution. After reacting with shaking in a constant temperature shaker at 30 °C at a rotation speed of 150 rpm for 6 h, the concentration of ReO4 - in the solution was measured by an ultraviolet-visible spectrophotometer. The results are shown in Table 1.

[0029] Table 1 Adsorption performance of different adsorbents for ReO4 - Adsorbent Adsorption capacity (mg / g) MPIL 68.26 WPU / MPIL 55.69 MPIL-DB-1 46.30 WPU / MPIL-DB-1 31.33 MPIL-DB-2 35.79 WPU / MPIL-DB-2 19.85 PU-0 0.13 Example 2 The preparation of MPIL was the same as that in Example 1.

[0030] A certain amount of MPIL and waterborne polyurethane (WPU) were added to deionized water, and it was vigorously stirred with a homogenizer (4×10 4 rpm) for 10 min until complete foaming occurred, and then freeze-dried to obtain a foam adsorbent with a MPIL content of 4 wt% (WPU / MPIL, the adsorption capacity for ReO4 - was 45.69 mg / g).

[0031] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A foam adsorbent, comprising a polyurethane foam matrix, characterized in that: The polyionic liquid shown by the following structural formula is dispersed in the polyurethane foam matrix. A - is a bis(trifluoromethylsulfonyl)imide anion or a halide ion, m > 0, n > 0; preferably, the ratio of m to n is 1:1 to 1:

10.

2. The foam adsorbent according to claim 1, wherein: The content of the polyionic liquid is 1-20 wt% of the polyurethane foam matrix, preferably 4-10 wt%.

3. The foam adsorbent according to claim 1, wherein: The number average molecular weight of the polyionic liquid is 4000-8000.

4. The preparation method of the foam adsorbent according to any one of claims 1 to 3, comprising: The polyionic liquid and aqueous polyurethane are mixed and stirred in water until foaming is complete, and then freeze-dried to obtain the foam adsorbent.

5. Use of the foam adsorbent according to any one of claims 1 to 3 in adsorbing ReO4 - and / or TcO4 - therein.

6. A polyionic liquid, characterized in that: The structure of the polyionic isolator is shown as follows: A - is a bis(trifluoromethylsulfonyl)imide anion or a halide ion, m > 0, n > 0; preferably, the ratio of m to n is from 1:1 to 1:

10.

7. The preparation method of the polyionic liquid according to claim 6, comprising: 1-Vinyl-3-cyanomethylimidazole bromide, 1-[(4-vinylphenyl)methyl]-1-methylpiperidinium bromide and an initiator are mixed and heated for polymerization in a solvent to obtain a polyionic liquid.

8. The preparation method according to claim 7, characterized in that: The initiator is azobisisobutyronitrile, and the temperature of the polymerization reaction is 20-60 °C.

9. The preparation method according to claim 7, characterized in that: The solvent in step (1) is dimethyl sulfoxide.

10. Use of the polyionic liquid according to claim 5 in adsorbing ReO4 - and / or TcO4 - therein.

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