An imidazole polyionic liquid modified MXene composite material, a preparation method thereof, and an application thereof

Abstract

The present invention relates to an imidazole polyionic liquid modified MXene composite material, a preparation method thereof and an application thereof, belonging to the field of preparation of environmental functional material adsorbents. A preparation method of an imidazole polyionic liquid modified MXene composite material is as follows: MXene and chloroacetic acid are dissolved in water, NaOH is added and stirred for reaction, and through washing, filtering and freeze-drying, carboxylated MXene is obtained; the carboxylated MXene and poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid are added into deionized water, ultrasonically dispersed, and after adding polyethyleneimine, stirred for reaction; after the reaction is completed, it is washed with deionized water and freeze-dried to obtain an imidazole polyionic liquid modified MXene composite material. The imidazole-based polyionic liquid modified MXene composite material of the present invention can rapidly adsorb and remove trace diclofenac sodium pollutants in water bodies.

Description

Technical Field

[0001] The invention relates to an imidazole polyionic liquid modified MXene composite material and a preparation method and application thereof, and belongs to the field of preparation of environmental functional material adsorbents. Background Art

[0002] Diclofenac sodium (DCF) is a non-steroidal anti-inflammatory drug that is often used in human medicine and aquaculture. It can cause certain harm to humans and the ecological environment. The large-scale use of diclofenac sodium, the harm of short-term exposure to pollutants cannot be detected, and it can be enriched in plants and animals through the food chain. After entering the human body, it can cause allergies, poisoning and other symptoms, which are harmful to human health (Bhadra, BN, Seo, PW, & Jhung, SH (2016). Adsorption of diclofenac sodium from water using oxidized activated carbon. Chemical Engineering Journal, 301, 27–34.); after entering the ecosystem, it will increase the drug resistance of microbial populations and destroy the stability of the ecosystem. In traditional sewage treatment plants, the degradation rate of sodium diclofenac is very slow (Guerra, ACS, Andrade, MBde, Santos, TRTdos, & Bergamasco, R. (2019). Adsorption of sodium diclofenac in aqueous medium using graphene oxide nanosheets. Environmental Technology, 1–26.), so the efficient removal of sodium diclofenac from water has become an urgent problem to be solved. Among many technologies, such as adsorption, membrane, biodegradation, ozone oxidation and electrochemical advanced oxidation processes, adsorption is favored because of its high efficiency, simplicity, low cost and no generation of toxic byproducts. Therefore, people have explored a variety of adsorbents, mainly including activated carbon, carbon nanotubes and metal organic frameworks. However, these adsorbents usually have certain limitations in practical applications, such as long equilibrium time, limited adsorption capacity, poor anti-interference ability and low stability. In order to solve these problems, the adsorbent should have ideal characteristics such as uniform pore size, suitable particle size, conducive to diffusion, dense adsorption sites, strong affinity for target pollutants and high stability.

[0003] Mxene is a new type of 2D material prepared by selectively etching Al atoms in the transition metal carbide Ti3AlC2. It has rich chemical compositions and unique properties, such as a controllable chemical surface, high specific surface area, hydrophilicity, abundant active surface sites, and a large number of functional groups (-OH and -O), etc. As a new type of adsorption material, it has attracted extensive attention and research in the field of environmental governance.

[0004] Imidazolium-based polyionic liquids are green solvents and are in a liquid state at room temperature or near room temperature. Polyionic liquids have the characteristics of low melting point, non-volatility, good thermal stability, and adjustable properties. Polymerized ionic liquids can reduce the loss of liquid ionic liquids, introduce more adsorption functional groups and active sites, and are widely used in the field of adsorption separation.

[0005] At present, there is a lack of research on the adsorption of diclofenac sodium wastewater with trace concentrations by imidazolium-based polyionic liquid-modified MXene composite adsorbent materials. The present invention proposes a preparation method and application of an imidazolium-based polyionic liquid-modified MXene composite adsorbent material. Summary of the Invention

[0006] In order to solve the above problems of the harm of diclofenac sodium, the present invention proposes a preparation method and application of an imidazolium-based polyionic liquid-modified MXene composite adsorbent. The purpose of the present invention is to provide a composite material rich in adsorption sites and functional groups and a method for adsorbing trace diclofenac sodium.

[0007] A preparation method of an imidazole polyionic liquid-modified MXene composite material,

[0008] Dissolve MXene and chloroacetic acid in water, add NaOH and stir to react. After washing, filtering, and freeze-drying, carboxylated MXene is obtained; add carboxylated MXene and poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid to deionized water, ultrasonically disperse, add polyethyleneimine and then stir to react; after the reaction is completed, wash with deionized water and freeze-dry to obtain an imidazole polyionic liquid-modified MXene composite material.

[0009] Preferably, the poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid is prepared by the following method: mix 1-imidazole acetic acid and 4-vinylbenzyl chloride, add hydroquinone, use ethanol as the reaction solvent, and react for a certain time under a nitrogen atmosphere; rotary evaporate to remove the solvent to obtain a yellow viscous liquid product, acetic acid-4-vinylbenzylimidazole monomer (IL); mix the acetic acid-4-vinylbenzylimidazole monomer and N’N-azobisisobutyronitrile, use ethanol as the solvent, and react under a nitrogen atmosphere; after the reaction is completed, rotary evaporate to remove the solvent and vacuum dry to obtain a yellow solid product - poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid.

[0010] Furthermore, the mass ratio of 1-imidazole acetic acid to 4-vinylbenzyl chloride is 1:1 to 1:5; the ratio of 1-imidazole acetic acid to ethanol is 1 g: 10 to 50 mL, the mass ratio of 1-imidazole acetic acid to hydroquinone is 1 g: 10 mg to 1:50 mg, the reaction time is 12 h to 48 h, and the reaction temperature is 30 °C to 50 °C.

[0011] Furthermore, the mass ratio of 4-vinylbenzylimidazole acetate monomer to N,N'-azobisisobutyronitrile is 3 g: 5 mg to 60 mg, the ratio of 4-vinylbenzylimidazole acetate monomer to ethanol is 1 g: 10 to 50 mL, the reaction time is 12 h to 48 h, the reaction temperature is 60 °C to 80 °C, and the vacuum drying time is 24 h to 48 h.

[0012] Preferably, the MXene is a graphene-like structure etched from the MAX phase in a hydrofluoric acid solution. The molecular formula of the MAX phase is Mn+1AXn, where n = 1, 2, 3. M is mainly early transition metal elements, including but not limited to Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta; A is Group III and Group IV main group elements, including but not limited to Al, P, S, Ge, As, Cd, In, Sn, Tl, and Pb; X is C and / or N elements.

[0013] Furthermore, in the present invention, M is preferably Ti or Mo; A is preferably Al or Cd.

[0014] Preferably, the ratio of MXene to water is 0.1 g: 100 mL to 0.1 g: 500 mL, the mass ratio of MXene to chloroacetic acid is 1:1 to 1:20, the mass ratio of added NaOH to the volume of the reaction solution is 0.1 g: 1 mL to 0.5 g: 1 mL, the reaction time is 1 h to 3 h, and the reaction temperature is 45 °C to 60 °C.

[0015] Preferably, the mass ratio of carboxylated MXene to poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid is 1:5 to 1:60, the mass ratio of carboxylated MXene to PEI is 1:1 to 1:5, the mass ratio of carboxylated MXene to the volume of deionized water is 1 g: 1 L to 1 g: 5 L, the reaction time is 12 h to 48 h, and the reaction temperature is 45 °C to 60 °C.

[0016] Another object of the present invention is to provide an imidazole polyionic liquid modified MXene composite material prepared by the above method.

[0017] Furthermore, the composite material is a multi-layer sandwich structure, and acidic functional groups -COOH are exposed on the surface and the framework.

[0018] By regulating the pH of the aqueous solution, the surface charge type of the material can be changed, and the pH swing effect is utilized to efficiently adsorb and remove DCF and realize the rapid regeneration and recycling of the adsorbent.

[0019] Another object of the present invention is to provide the application of the above-mentioned imidazole polyionic liquid modified MXene composite material as a diclofenac adsorbent.

[0020] Further, the imidazole polyionic liquid modified MXene composite material is added to the polluted water containing diclofenac for adsorption.

[0021] Further, the MXene composite material adsorbed with diclofenac is desorbed by the following method: the composite material after adsorption is filtered and washed, then soaked in a NaOH solution with a pH of 11 for 24 h, and finally filtered and washed to neutrality and dried in vacuum.

[0022] The beneficial effects of the present invention are as follows: the imidazole-based polyionic liquid modified MXene composite material of the present invention can rapidly adsorb and remove trace diclofenac sodium pollutants in water. Compared with MXene without loaded PIL, the adsorption saturation capacity is doubled, and compared with pure PIL for adsorbing diclofenac sodium, the adsorption rate is significantly increased. The composite material prepared in the present invention has a multi-layer sandwich structure, and a large number of acidic functional groups -COOH are exposed on the surface and the framework. By regulating the pH of the aqueous solution, the surface charge type of the material can be changed, and the pH swing effect is utilized to efficiently adsorb and remove DCF and realize the rapid regeneration and recycling of the adsorbent. Description of the Drawings

[0023] Figure 1 It is the SEM image of the MXene nanosheets prepared in Example 1 of the present invention;

[0024] Figure 2 It is the SEM image of the carboxylated MXene nanosheets prepared in Example 1 of the present invention;

[0025] Figure 3 It is the SEM image of the imidazole-based polyionic liquid modified MXene composite adsorbent;

[0026] Figure 4 It is the adsorption effect diagram of the composite adsorbents prepared in Example 1 and Example 2 of the present invention on diclofenac sodium. Detailed Embodiments

[0027] The following non-limiting embodiments can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way.

[0028] In the following embodiments, the test methods are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0029] One of the specific embodiments:

[0030] A preparation method of an imidazole polyionic liquid modified MXene composite adsorbent. The preparation of the composite adsorbent mainly includes the following steps

[0031] (1) Dissolve MXene and chloroacetic acid in water, add NaOH and stir to react. Then wash the sample to neutrality, filter and collect, and freeze-dry to obtain carboxylated MXene.

[0032] (2) Pour 1-imidazoleacetic acid and 4-vinylbenzyl chloride into a three-necked flask, add hydroquinone, use ethanol as the reaction solvent, and react for a certain time under a nitrogen atmosphere. Rotate and evaporate to remove the solvent to obtain a yellow viscous liquid product, 4-vinylbenzylimidazole acetate monomer (IL). Put the 4-vinylbenzylimidazole acetate monomer and N,N'-azobisisobutyronitrile into a three-necked flask, use ethanol as the solvent, and react under a nitrogen atmosphere. After the reaction is completed, rotate and evaporate to remove the solvent, and vacuum dry to obtain a yellow solid product, poly(1-acetate-4-vinylbenzylimidazole) ionic liquid (PIL).

[0033] (3) Add carboxylated MXene and PIL to deionized water, ultrasonically disperse, add polyethyleneimine (PEI), and stir to react. After the reaction is completed, wash with deionized water and freeze-dry to obtain an imidazole polyionic liquid modified MXene composite material adsorbent (PCM).

[0034] Preferably, MXene is a graphene-like structure etched from the MAX phase in a hydrofluoric acid solution. The specific molecular formula of the MAX phase is Mn+1AXn (n = 1, 2 or 3), M is mainly early transition metal elements, including but not limited to Sc, Ti, V, Cr, Zr, Nb, Mo, Hf and Ta; A is group III and IV main group elements, including but not limited to Al, P, S, Ge, As, Cd, In, Sn, Tl and Pb; X refers to C and / or N elements.

[0035] Preferably, in the step (1), the ratio of MXene to water is 0.1 g:100 mL to 0.1 g:500 mL, the mass ratio of MXene to chloroacetic acid is 1:1 to 1:20, the mass of added NaOH to the volume of the reaction solution is 0.1 g:1 mL to 0.5 g:1 mL, the reaction time is 1 h to 3 h, and the reaction temperature is 45 °C to 60 °C.

[0036] Preferably, in the step (2), the mass ratio of 1-imidazoleacetic acid to 4-vinylbenzyl chloride is 1:1 to 1:5; the mass ratio of 1-imidazoleacetic acid to the volume of ethanol is 1 g:10 to 50 mL, the mass ratio of 1-imidazoleacetic acid to hydroquinone is 1 g:10 mg to 1:50 mg, the reaction time is 12 h to 48 h, and the reaction temperature is 30°C to 50°C

[0037] Preferably, in the step (2), the mass ratio of 4-vinylbenzylimidazole acetate monomer to N,N'-azobisisobutyronitrile is 3 g:5 mg to 60 mg, the mass ratio of 4-vinylbenzylimidazole acetate monomer to the volume of ethanol is 1 g:10 to 50 mL, the reaction time is 12 h to 48 h, the reaction temperature is 60°C to 80°C, and the vacuum drying time is 24 h to 48 h.

[0038] Preferably, in the step (3), the mass ratio of carboxylated MXene to poly(1-4-vinylbenzylimidazole acetate) ionic liquid is 1:5 to 1:60, the mass ratio of carboxylated MXene to PEI is 1:1 to 1:5, the mass ratio of carboxylated MXene to the volume of deionized water is 1 g:1 L to 1 g:5 L, the reaction time is 12 h to 48 h, and the reaction temperature is 45°C to 60°C.

[0039] Example 1

[0040] (1) Preparation of MXene nanosheets by lithium fluoride etching method: Prepare an HCl solution with a concentration of 9 mol / L, weigh 8 g of lithium fluoride and add it to the solution, and then add 5 g of Ti3AlC2 powder. After reacting for 24 h, centrifuge the mixed solution at a speed of 3000 revolutions per minute for about 10 minutes, and collect the precipitate. The precipitate is rinsed with ultrapure water. Then, shake the mixed solution vigorously until the color of the supernatant turns dark green. Collect the supernatant and centrifuge. Finally, a MXene sample is obtained after vacuum freeze-drying.

[0041] (2) Preparation of carboxylated MXene nanosheets: Add MXene and chloroacetic acid to water at a mass ratio of 1:3, the ratio of MXene to water is 0.1 g:100 mL, the mass of NaOH added is in a ratio of 0.3 g:1 mL to the volume of the reaction solution, react for 1.5 h, the reaction temperature is 45°C, after the reaction, wash with deionized water until neutral, and finally freeze-dry the product to obtain carboxylated MXene.

[0042] (3) Pour 1-imidazoleacetic acid and 4-vinylbenzyl chloride into a three-necked flask at a mass ratio of 1:3, and carry out the reaction using ethanol as the solvent. The mass of 1-imidazoleacetic acid and the volume of ethanol are in a ratio of 1 g:30 mL. Add hydroquinone to the mixed solution at a mass ratio of 30 mg:1 g to 1-imidazoleacetic acid, and react at 30 °C for 12 h under a nitrogen atmosphere. After the reaction is completed, rotary evaporate to remove the solvent to obtain the yellow viscous liquid product 4-vinylbenzylimidazole acetate monomer (IL).

[0043] (4) Put 4-vinylbenzylimidazole acetate monomer and N,N'-azobisisobutyronitrile into a three-necked flask at a mass ratio of 3 g:30 mg, use ethanol as the solvent, and react at a ratio of 1 g of 4-vinylbenzylimidazole acetate monomer to 30 mL of ethanol volume for 12 h at a reaction temperature of 60 °C. Rotary evaporate to remove the solvent, and finally vacuum dry at 60 °C for 36 h to obtain the yellow solid product poly(1-4-vinylbenzylimidazole acetate) ionic liquid (PIL 30 ).

[0044] (5) Dissolve carboxylated MXene and PIL 30 in deionized water at a mass ratio of 1:30. Stir and dissolve the carboxylated MXene mass and the deionized water volume at a ratio of 1 g:3 L. Ultrasonicate the mixed solution, then add PEI for reaction. The mass ratio of PEI to carboxylated MXene is 3:1, and stir and react at 45 °C for 12 h. After the reaction is completed, wash several times and freeze-dry to obtain the imidazole polyionic liquid modified MXene composite adsorbent (PCM 30 ).

[0045] (6) Accurately weigh 10 mg of the composite adsorbent PCM 30 , take 10 mL of a 30 mg / L diclofenac sodium solution, mix the two evenly, and oscillate and adsorb at 2000 rpm / min for 2 h at room temperature. The removal rate of diclofenac sodium by PCM 30 reaches 83.8%.

[0046] (7) Filter and wash the composite adsorbent PCM 30 after adsorption, then soak it in a NaOH solution with a pH of 11 for 24 h, and finally filter and wash it to neutral, vacuum dry and collect. Repeat the operation in step (6), and the removal rate of the adsorbent for diclofenac sodium reaches 79.6%.

[0047] Example 2

[0048] (1) Preparation of MXene nanosheets by lithium fluoride etching method: The same as in Example 1.

[0049] (2) Preparation of carboxylated MXene nanosheets: MXene and chloroacetic acid were added to water at a mass ratio of 1:20. The ratio of MXene to water was 0.1 g:500 mL. The mass ratio of added NaOH to the volume of the reaction solution was 0.5 g:1 mL. The reaction was carried out for 3 h at a reaction temperature of 60 °C. After the reaction, it was washed with deionized water until neutral, and finally the product was freeze-dried to obtain carboxylated MXene.

[0050] (3) 1-Imidazoleacetic acid and 4-vinylbenzyl chloride were poured into a three-necked flask at a mass ratio of 1:5, and the reaction was carried out with ethanol as the solvent. The mass of 1-imidazoleacetic acid and the volume of ethanol were in a ratio of 1 g:50 mL. Hydroquinone was added to the mixed solution at a mass ratio of 50 mg:1 g to 1-imidazoleacetic acid. The reaction was carried out at 50 °C for 48 h under a nitrogen atmosphere. After the reaction, the solvent was removed by rotary evaporation to obtain a yellow viscous liquid product, 4-vinylbenzylimidazole acetate monomer (IL).

[0051] (4) 4-vinylbenzylimidazole acetate monomer and N,N'-azobisisobutyronitrile were placed in a three-necked flask at a mass ratio of 3 g:60 mg. The reaction was carried out with the ratio of the mass of 4-vinylbenzylimidazole acetate monomer to the volume of ethanol being 1 g:50 mL. The reaction time was 48 h and the reaction temperature was 80 °C. The solvent was removed by rotary evaporation, and finally it was vacuum-dried at 60 °C for 48 h to obtain a yellow solid product, poly(1-4-vinylbenzylimidazole acetate) ionic liquid (PIL 60 ).

[0052] (5) Carboxylated MXene and PIL 60 were dissolved in deionized water at a mass ratio of 1:50. The mass of carboxylated MXene and the volume of deionized water were in a ratio of 1 g:5 L and stirred to dissolve. The mixed solution was ultrasonicated, and then PEI and carboxylated MXene were reacted at a mass ratio of 1:5. The reaction was fully stirred at 60 °C for 48 h. After the reaction, it was washed many times and freeze-dried to obtain an imidazole polyionic liquid modified MXene composite adsorbent (PCM 50 ).

[0053] (6) Accurately weigh 10 mg of the composite adsorbent PCM 50 , take 10 mL of a diclofenac sodium solution with a concentration of 30 mg / L, and mix the two evenly. At room temperature, it was oscillated and adsorbed at 2000 rpm for 2 h. The removal rate of diclofenac sodium by PCM 50 reached 97.1%.

[0054] (7) The composite adsorbent PCM 50Perform filtration and washing, then soak in a NaOH solution with a pH of 11 for 24 h, and finally filter and wash again until neutral, collect by vacuum drying, repeat the operation in step (6), and the removal rate of the adsorbent for diclofenac sodium reaches 93.2%.

Claims

1. A preparation method of an imidazole polyionic liquid modified MXene composite material, characterized in that: Dissolve MXene and chloroacetic acid in water, add NaOH and stir to react. After washing, filtering and freeze-drying, carboxylated MXene is obtained; add carboxylated MXene and poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid into deionized water, ultrasonically disperse, add polyethyleneimine PEI and then stir to react; after the reaction is completed, wash with deionized water and freeze-dry to obtain an imidazole polyionic liquid modified MXene composite material. The poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid is prepared by the following method: Mix 1-imidazole acetic acid and 4-vinylbenzyl chloride, add hydroquinone, use ethanol as the reaction solvent, and react for a certain time under a nitrogen atmosphere; Rotate to evaporate the solvent to obtain a yellow viscous liquid product, acetic acid-4-vinylbenzylimidazole monomer IL; Mix the acetic acid-4-vinylbenzylimidazole monomer with N,N'-azobisisobutyronitrile, use ethanol as the solvent, and react under a nitrogen atmosphere; After the reaction is completed, rotate to evaporate the solvent and vacuum dry to obtain a yellow solid product - poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid.

2. The method according to claim 1, characterized in that: The MXene is a graphene-like structure obtained by etching the MAX phase in a hydrofluoric acid solution. The molecular formula of the MAX phase is M n+1 AX n , where n = 1, 2, 3, M is Ti or Mo, A is Al or Cd, and X is C or N element.

3. The method according to claim 1, characterized in that: The ratio of MXene to water is 0.1 g:100 mL to 0.1 g:500 mL, the mass ratio of MXene to chloroacetic acid is 1:1 to 1:20, the reaction time is 1 h to 3 h, and the reaction temperature is 45 °C to 60 °C.

4. The method according to claim 1, wherein: The mass ratio of the carboxylated MXene to the poly(1-acetic acid-4-vinylbenzylimidazole) ionic liquid is 1:5 to 1:60, the mass ratio of the carboxylated MXene to PEI is 1:1 to 1:5, the mass of the carboxylated MXene to the volume of deionized water ratio is 1 g:1 L to 1 g:5 L, the reaction time is 12 h to 48 h, and the reaction temperature is 45 °C to 60 °C.

5. The method according to claim 1, wherein: The mass ratio of 1-imidazole acetic acid to 4-vinylbenzyl chloride is 1:1 to 1:5; the ratio of 1-imidazole acetic acid to ethanol is 1 g:10 to 50 mL, the mass ratio of 1-imidazole acetic acid and hydroquinone is 1 g:10 mg to 1:50 mg, the reaction time is 12 h to 48 h, and the reaction temperature is 30 °C to 50 °C; The mass ratio of the acetic acid-4-vinylbenzylimidazole monomer to N,N'-azobisisobutyronitrile is 3 g:5 mg to 60 mg, the ratio of the acetic acid-4-vinylbenzylimidazole monomer to ethanol is 1 g:10 to 50 mL, the reaction time is 12 h to 48 h, the reaction temperature is 60 °C to 80 °C, and the vacuum drying time is 24 h to 48 h.

6. The imidazole polyionic liquid modified MXene composite material prepared by the method according to claim 1.

7. Application of the imidazole polyionic liquid modified MXene composite material according to claim 6 as a diclofenac adsorbent.

8. The application according to claim 7, characterized in that: Add the imidazole polyionic liquid modified MXene composite material into the polluted water containing diclofenac for adsorption.

9. The application according to claim 8, wherein: The MXene composite material adsorbing diclofenac is desorbed by the following method: the composite material after adsorption is filtered and washed, then soaked in a NaOH solution with a pH value of 11 for 24 h, and finally filtered and washed until neutral, and then dried under vacuum.

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