Imidazolium salt polymer adsorbent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adsorbent preparation, in particular to an imidazolium salt polymer adsorbent as well as a preparation method and application thereof. The preparation method of the imidazolium salt polymer adsorbent comprises the following steps: mixing a polybromophenyl organic compound, imidazole, alkali and a catalyst, and carrying out nucleophilic substitution reaction under the action of the catalyst and the alkali to obtain a triimidazolyl organic monomer; the preparation method comprises the following steps: dissolving a triimidazolyl organic monomer and 1, 4-di (bromomethyl) benzene in an organic solvent, and carrying out quaternization reaction to obtain the imidazolium salt polymer adsorbent. The imidazolium salt polymer adsorbent prepared by the method disclosed by the invention not only can accurately identify and adsorb Cr2O7 < 2-> and remarkably improve the removal efficiency of Cr2O7 < 2->, but also can keep an efficient working state in a wide pH value range. Meanwhile, the material can be easily separated from wastewater and can be repeatedly used after being subjected to simple regeneration treatment, so that cyclic utilization of resources is realized.

Description

Technical Field

[0001] The invention relates to the technical field of adsorbent preparation, and in particular to an imidazolium salt polymer adsorbent and a preparation method and application thereof. Background Art

[0002] With the acceleration of industrialization, environmental pollution has become more serious. The disorderly expansion of industry and the lack of waste management have further exacerbated this trend, causing a large number of harmful substances to invade water bodies. Among the many pollutants, heavy metals pose a severe challenge to aquatic ecosystems due to their high solubility, significant toxicity, easy bioaccumulation and difficulty in degradation. In particular, hexavalent chromium Cr(VI) has become one of the most dangerous types of pollutants due to its strong carcinogenicity and high toxicity. Dichromate (Cr2O7 2- ) is the most common form of Cr(VI) in wastewater and is widely used in metallurgy, leather tanning, papermaking, printing and dyeing industries. Therefore, how to effectively purify wastewater containing carcinogenic Cr2O7 2- The wastewater has become a key issue that needs to be solved urgently.

[0003] At present, the traditional treatment methods for dichromate-containing pollutants mainly include chemical precipitation, ion exchange, reverse osmosis technology and granular activated carbon adsorption. However, although the adsorbent materials prepared by the existing technology have good adsorption performance, they still face many limitations in practical application. Specifically, these adsorbent materials prepared by the existing technology generally have the defects of low capture efficiency, difficulty in recycling, poor selectivity and susceptibility to pH fluctuations. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an imidazolium salt polymer adsorbent and a preparation method and application thereof. The present invention uses polybrominated phenyl organic compounds and imidazole as raw materials. Under the action of a catalyst and a base, the polybrominated phenyl organic compounds and imidazole undergo a nucleophilic substitution reaction to obtain a triimidazolyl organic monomer; then the triimidazolyl organic monomer and 1,4-di(bromomethyl)benzene are dissolved in an organic solvent, and the triimidazolyl organic monomer and 1,4-di(bromomethyl)benzene undergo a quaternization reaction to obtain an imidazolium salt polymer adsorbent. The present invention obtains an imidazolium salt polymer adsorbent through a two-step organic synthesis reaction of a nucleophilic substitution reaction and a quaternization reaction, which can not only accurately identify and adsorb Cr2O7 2- , significantly improve Cr2O7 2- It has a high removal efficiency and can maintain efficient working state in a wide range of pH values. At the same time, it is easy to separate from wastewater and can be reused after simple regeneration treatment, thus achieving the recycling of resources and sustainable development of the environment.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first object of the present invention is to provide a method for preparing an imidazolium salt polymer adsorbent, comprising the following steps:

[0007] A polybrominated phenyl organic compound, imidazole, a base and a catalyst are mixed, and under the action of the catalyst and the base, the bromine atom in the polybrominated phenyl organic compound undergoes a nucleophilic substitution reaction with the nitrogen atom in the imidazole molecule to obtain a tri-imidazolyl organic monomer; wherein the molar ratio of the polybrominated phenyl organic compound to the imidazole is 1:3-100; in this reaction system, the imidazole not only participates in the reaction as a raw material, but also melts under high temperature conditions to act as a solvent, which helps to promote the reaction; if the imidazole content is too low, the yield will be significantly reduced, and even the reaction cannot be carried out.

[0008] The triimidazolyl organic monomer and 1,4-di(bromomethyl)benzene are dissolved in an organic solvent, and the imidazole nitrogen atom in the triimidazolyl organic monomer and the bromomethyl carbon atom in 1,4-di(bromomethyl)benzene are subjected to a quaternization reaction to obtain an imidazolium salt polymer adsorbent.

[0009] Preferably, the molar ratio of polybrominated phenyl organic compound to imidazole is 1:30 。

[0010] Preferably, the conditions for the nucleophilic substitution reaction are: reacting at 60°C to 180°C for 12h to 72h ， Increasing the temperature and extending the nucleophilic substitution reaction time can help accelerate the reaction rate.

[0011] Preferably, the molar ratio of the triimidazolyl organic monomer to 1,4-di(bromomethyl)benzene is 1:1-3. A molar ratio below or above this range will result in the formation of oligomers, which in turn leads to a decrease in yield and deterioration in the performance of the imidazolium salt polymer adsorbent.

[0012] Preferably, the quaternization reaction conditions are: reacting at 60° C. to 140° C. for 2 h to 24 h.

[0013] Preferably, the polybrominated phenyl organic compound is selected from 1,3,5-tris(4-bromophenyl)benzene, 2,4,6-tris-(4-bromophenyl)-1,3,5-triazine, 1,3,5-tribromobenzene or tris-(4-bromophenyl)amine.

[0014] Preferably, the catalyst is selected from at least one of copper sulfate, copper carbonate, copper acetate and cuprous iodide, and the added amount of the catalyst is 0.1% to 5% of the molar amount of the polybrominated phenyl organic compound.

[0015] Preferably, the base is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide and potassium tert-butoxide, and the amount of the base added is 1 to 50 times the molar amount of the polybrominated phenyl organic compound.

[0016] Preferably, the organic solvent is selected from at least one of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, dioxane, toluene and tetrahydrofuran.

[0017] The second object of the present invention is to provide an imidazolium salt polymer adsorbent prepared by the above preparation method; wherein the imidazolium salt polymer adsorbent contains an imidazolium salt unit.

[0018] The third object of the present invention is to provide the use of the above-mentioned imidazolium salt polymer adsorbent in the preparation of anionic pollutant adsorbents in water; wherein the anionic pollutants are selected from chromate, dichromate, arsenate, phosphate or permanganate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a method for preparing an imidazolium salt polymer adsorbent, wherein a polybrominated phenyl organic compound, imidazole, a base and a catalyst are mixed, and under the action of the catalyst and the base, the bromine atom in the polybrominated phenyl organic compound undergoes a nucleophilic substitution reaction with the nitrogen atom in the imidazole molecule to obtain a tri-imidazolyl organic monomer; wherein the molar ratio of the polybrominated phenyl organic compound to the imidazole is 1:3 to 100; the tri-imidazolyl organic monomer and 1,4-di(bromomethyl)benzene are dissolved in an organic solvent, and a quaternization reaction is performed using the imidazole nitrogen atom in the tri-imidazolyl organic monomer and the bromomethyl carbon atom in 1,4-di(bromomethyl)benzene to obtain an imidazolium salt polymer adsorbent; wherein the imidazolium salt polymer adsorbent contains an imidazolium salt unit. The present invention obtains an imidazolium salt polymer adsorbent through a two-step organic synthesis reaction of a nucleophilic substitution reaction and a quaternization reaction, which can not only accurately identify and adsorb Cr2O7 2- , avoiding unnecessary interference with other ions and significantly improving Cr2O7 2- The removal efficiency is high and the working state can be maintained efficiently in a wide range of pH values. At the same time, the imidazolium salt polymer adsorbent of the present invention is also easy to separate from wastewater and can be reused after a simple regeneration treatment, thereby achieving the recycling of resources and sustainable development of the environment.

[0021] Among them, the base promotes the deprotonation of the imidazole molecule by affecting the ionization state and activity of the imidazole molecule, making the nitrogen atom in the imidazole molecule more active, thereby undergoing a nucleophilic substitution reaction with the bromine atom.

[0022] In addition, the imidazolium salt polymer adsorbent prepared by the present invention has a complex porous structure and a high-density distribution of imidazolium salt units, showing excellent specific surface area and strong water absorption. The imidazolium salt polymer adsorbent can quickly exchange with anionic pollutants in the water body by utilizing the abundant bromine anions around the positively charged main body of the imidazolium salt unit. At the same time, the complex porous structure of the imidazolium salt polymer adsorbent further enhances the adsorption efficiency. Therefore, the imidazolium salt polymer adsorbent prepared by the present invention can effectively purify anionic pollutants in water, such as chromate, dichromate, arsenate, phosphate and permanganate.

[0023] 2. The imidazolium salt polymer adsorbent prepared by the present invention has the characteristics of high mechanical strength, strong thermal stability, and acid and alkali resistance. In the preparation process, a stable covalent bond (such as a CN bond) is formed between the polybrominated phenyl organic compound, imidazole and 1,4-di(bromomethyl)benzene through a nucleophilic substitution reaction and a quaternization reaction. These covalent bonds not only enhance the mechanical strength of the imidazolium salt polymer adsorbent, but also ensure its stability in harsh environments.

[0024] In addition, in the imidazolium salt polymer adsorbent prepared by the present invention, the triimidazolyl organic monomer and the chemical bond connecting the triimidazolyl organic monomer and the 1,4-di(methylene)benzene unit (such as the CN bond formed by the quaternization reaction) have strong rigidity, which helps to maintain the stability of the imidazolium salt polymer adsorbent structure under thermal stress. At the same time, the introduction of the imidazolium salt unit not only improves the adsorption performance of the imidazolium salt polymer adsorbent, but also because of its chemical stability, the imidazolium salt polymer adsorbent can maintain the integrity of its structure and function in an acidic and alkaline environment. In addition, the CC bond and CN bond in the structure of the imidazolium salt polymer adsorbent also have high chemical stability, further enhancing the acid and alkali resistance of the imidazolium salt polymer adsorbent.

[0025] 3. The saturated adsorption capacity of the adsorbents reported so far is mostly less than 400, and the adsorption rate is generally no more than 70 mg / g min, and the adsorption rate of many adsorbents is less than 10 mg / g min. In contrast, the imidazolium salt polymer adsorbent prepared by the present invention has a large adsorption capacity, fast adsorption rate, strong anti-interference ability, wide pH adaptability and excellent reusability for anionic pollutants in wastewater. -4 mol / L aqueous solutions of different types of anionic pollutants, using 15 mg of imidazolium salt polymer adsorbent, the saturated adsorption capacity of K2Cr2O7 and AsH2KO4 was 423 mg / g and 443 mg / g respectively; at a concentration of 5.13×10 -4In a mol / L potassium dichromate aqueous solution, the imidazolium salt polymer adsorbent prepared by the present invention has the fastest adsorption rate, reaching 81 mg / g min. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the IR spectra of the imidazolium salt polymer adsorbent in Example 1 and Example 2, wherein: Figure 1 (a) is the IR spectrum of the imidazolium salt polymer adsorbent in Example 1, Figure 1 (b) is the IR spectrum of the imidazolium salt polymer adsorbent in Example 2.

[0027] Figure 2 is the NMR spectrum of the imidazolium salt polymer adsorbent in Example 1 and Example 2, wherein: Figure 2 (a) is the NMR spectrum of the imidazolium salt polymer adsorbent in Example 1, Figure 2 (b) is the NMR spectrum of the imidazolium salt polymer adsorbent in Example 2.

[0028] Figure 3 is the SEM spectrum of the imidazolium salt polymer adsorbent in Example 1 and Example 2, wherein: Figure 3 (a) is the SEM spectrum of the imidazolium salt polymer adsorbent in Example 1, Figure 3 (b) is the SEM spectrum of the imidazolium salt polymer adsorbent in Example 2.

[0029] Figure 4 is the thermogravimetric spectrum of the imidazolium salt polymer adsorbent in Example 1 and Example 2, wherein: Figure 4 (a) is the thermogravimetric spectrum of the imidazolium salt polymer adsorbent in Example 1, Figure 4 (b) is the thermogravimetric spectrum of the imidazolium salt polymer adsorbent in Example 2.

[0030] Figure 5 is the X-ray photoelectron spectrum of the imidazolium salt polymer adsorbent in Example 1 and Example 2, wherein: Figure 5 (a) is the X-ray photoelectron spectrum of the imidazolium salt polymer adsorbent in Example 1, Figure 5 (b) is the X-ray photoelectron spectrum of the imidazolium salt polymer adsorbent in Example 2.

[0031] Figure 6 The figure is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 1 and Example 2 under different pH conditions, wherein: Figure 6 (a) is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 1 under different pH conditions. Figure 6(b) is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 2 under different pH conditions.

[0032] Figure 7 The figure is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 1 and Example 2 under the conditions of different interfering ions, wherein: Figure 7 (a) is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 1 under the conditions of different interfering ions. Figure 7 (b) is a graph showing the adsorption of dichromate by the imidazolium salt polymer adsorbent in Example 2 under the conditions of the presence of different interfering ions.

[0033] Figure 8 The results of the column chromatography experiment and the recovery experiment of the imidazolium salt polymer adsorbent for adsorbing dichromate in Example 1 and Example 2 are shown, wherein: Figure 8 (a) is a column chromatography experiment diagram of the adsorption of dichromate by the imidazolium salt polymer adsorbent in Examples 1 and 2, Figure 8 (b) is a graph showing the experimental results of the recovery and utilization of dichromate adsorbed by the imidazolium salt polymer adsorbent in Examples 1 and 2.

[0034] Fig. 9 The present invention provides a synthetic technology roadmap for the imidazolium salt polymer adsorbent. DETAILED DESCRIPTION

[0035] The following will be combined with the data in the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the prior art, adsorption materials prepared by the prior art, such as adsorbents and granular activated carbon, are used to treat the dichromate-containing (Cr2O7 2- ) wastewater, it is usually impossible to efficiently capture such toxic ions, and after the treatment process, the adsorbent materials are often difficult to recycle and reuse, reducing their economic and environmental friendliness. In addition, these adsorbents are not very selective and tend to adsorb other non-target substances in the water at the same time, affecting the purification effect. More importantly, changes in the pH value of the water body will have a significant impact on the performance of these adsorbents, limiting their application in complex water conditions.

[0037] In view of the problems existing in the prior art, the present invention provides a method for preparing an imidazolium salt polymer adsorbent, comprising the following steps: mixing a polybrominated phenyl organic compound, imidazole, a base and a catalyst, and under the action of the catalyst and the base, a bromine atom in the polybrominated phenyl organic compound reacts with a nitrogen atom in an imidazole molecule to undergo a nucleophilic substitution reaction to obtain a tri-imidazolyl organic monomer; wherein the molar ratio of the polybrominated phenyl organic compound to the imidazole is 1:3-100; dissolving the tri-imidazolyl organic monomer and 1,4-di(bromomethyl)benzene in an organic solvent, and performing a quaternization reaction using the imidazole nitrogen atom in the tri-imidazolyl organic monomer and the bromomethyl carbon atom in the 1,4-di(bromomethyl)benzene to obtain the imidazolium salt polymer adsorbent.

[0038] For ionic compounds, the higher the charge density, the greater the electrostatic attraction generated. The imidazolium salt polymer adsorbent obtained by the preparation method of the present invention is an adsorbent material with cations as the main body, and its main body is an imidazolium salt unit with a positive charge, and the surrounding is rich in bromine anions as counter ions. The present invention utilizes the positive charge of the imidazolium salt unit to efficiently exchange with anionic pollutants in water bodies (such as chromate, dichromate, arsenate, phosphate or permanganate as negative divalent or negative trivalent anions). These high-valent anions are compared to negative monovalent anions (such as F - , Cl - Br - ,I - ), which has a stronger electrostatic attraction to the imidazolium salt polymer adsorbent body, thereby achieving highly selective capture of target pollutants. At the same time, the complex porous structure of the imidazolium salt polymer adsorbent enhances the adsorption efficiency, thereby improving the selectivity and capture efficiency of the imidazolium salt polymer adsorbent; in addition, the chemical stability of the imidazolium salt unit enables the imidazolium salt polymer adsorbent to maintain the integrity of its structure and function in an acidic and alkaline environment, overcoming the problem that the adsorbent material prepared by the prior art is easily affected by pH fluctuations.

[0039] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0040] Example 1

[0041] A method for preparing an imidazolium salt polymer adsorbent comprises the following steps:

[0042] S1. Add 0.543 g (1 mmol) of 1,3,5-tris-(4-bromophenyl)benzene, 2.040 g (30 mmol) of imidazole, 2.480 g (18 mmol) of K2CO3 and 0.050 g (0.2 mmol) of CuSO 4.5H2O, heated at 150℃ for 48h, melted into a dark red solution, and the reaction was complete after monitoring by TLC.

[0043] The mixed solution was added to 1000 mL of distilled water, ultrasonically dispersed, filtered, washed three times with 100 mL of deionized water, and then extracted three times with 100 mL of methanol. The mixture was filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 0.402 g (0.797 mmol) of 1,3,5-tri-(4-imidazolylphenyl)benzene as a white solid with a yield of 79.7%.

[0044] 1 H NMR (400MHz, DMSO-d6): δ8.36(s,3H, imidazole-H),8.06(d, 3 J=8.5Hz,6H,Ar-H),8.01(s,3H,Ar-H),7.84(s,3H,imidazole-H),7.80(d,3J=8.5Hz,6H,Ar-H),7.15ppm(s,3H,imidazole-H). 13 C NMR(100MHz,DMSO-d6):140.6(Ar-C),138.3(Ar-C),136.4(Ar-C),135.5(NCN),129.9(imidazo le-C),128.6(Ar-C),124.4(Ar-C),120.6(Ar-C),117.9ppm(imidazole-C).HRMS(ESI,positive ions):m / z 505.2133(calcd for[M+H] + 505.2141).Anal.Calcd for(C 33 H 24 N6·H2O):C,75.82;H,5.05;N,16.10.Found:C,75.86;H,5.03;N,15.99, as Figure 2 As shown in (a) in .

[0045] Wherein, the chemical structural formula of 1,3,5-tris-(4-imidazolylphenyl)benzene is:

[0046]

[0047] S2. Dissolve 0.069 g (0.134 mmol) of 1,3,5-tris-(4-imidazolylphenyl)benzene and 0.059 g (0.224 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 120 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed with DMF and 2 mL of ethanol 5 times, and vacuum dried at 60 °C for 12 h to obtain 89 mg of imidazolium salt polymer adsorbent, ImIP1, with a yield of 73.8%.

[0048] FT-IR(KBr,cm -1 ):3415(b),3066(b),2842(w),1608(m),1551(s),1518(s),1456(m),1408(m ),1373(m),1345(m),1223(s),1192(s),1021(m),964(m),837(s),737(m), such as Figure 1 As shown in (a) in .

[0049] Example 2

[0050] A method for preparing an imidazolium salt polymer adsorbent is the same as the preparation method of Example 1, except that 1,3,5-tris-(4-bromophenyl)benzene in S1 is replaced by 2,4,6-tris-(4-bromophenyl)-1,3,5-triazine, comprising the following steps:

[0051] S1. Add 3.276 g (6 mmol) of 2,4,6-tris-(4-bromophenyl)-1,3,5-triazine, 12.254 g (1800 mmol) of imidazole, 16.585 g (120 mmol) of K2CO3 and 0.3 g (1.2 mmol) of CuSO 4. 5H2O, heated at 150℃ for 48h, melted into a dark red solution, and the reaction was complete after monitoring by TLC.

[0052] The mixed solution was added to 1000 mL of distilled water, ultrasonically dispersed, filtered, washed 3 times with 100 mL of deionized water, extracted 3 times with 200 mL of methanol, filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 3.019 g (5.948 mmol) of 2,4,6-tris-(4-imidazolylphenyl)-1,3,5-triazine as a yellow solid with a yield of 99.1%.

[0053] 1H NMR (400MHz, CDCl3): δ8.91(d,J=6.8Hz,6H,Ar-H),8.03(s,3H,imidazole-H),7.64(d,J=6.8Hz,6H,Ar-H),7.44(s,3H,imidazole-H),7.29(s,3H,imidazole-H), such as Figure 2 As shown in (b) in .

[0054] Wherein, the chemical structure of 2,4,6-tris-(4-imidazolylphenyl)-1,3,5-triazine is:

[0055]

[0056] S2. Dissolve 0.067 g (0.134 mmol) of 2,4,6-tris-(4-imidazolylphenyl)-1,3,5-triazine and 0.059 g (0.224 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 120 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed 5 times with DMF and 2 mL of ethanol, and vacuum dried at 60 °C for 12 h to obtain 104 mg of imidazolium salt polymer adsorbent, ImIP2, with a yield of 96.5%.

[0057] FT-IR(KBr,cm -1 ):3415(b),3060(b),2829(vw),1600(m),1549(s),1512(s),1419(w),1328(s),1291 (s),1226(s),1191(s),1081(s),1021(w),970(m),837(s),726(s),621(m),545(m), such as Figure 1 As shown in (b) in .

[0058] Example 3

[0059] A method for preparing an imidazolium salt polymer adsorbent is the same as the preparation method of Example 1, except that 1,3,5-tris-(4-bromophenyl)benzene in S1 is replaced by 1,3,5-tribromobenzene, comprising the following steps:

[0060] S1. Add 1.260 g (4 mmol) of 1,3,5-tribromobenzene, 8.17 g (120 mmol) of imidazole, 10 g (72 mmol) of K2CO3 and 0.1 g (0.4 mmol) of CuSO 4. 5H2O, heated at 150℃ for 48h, melted into a dark red solution, and the reaction was complete after monitoring by TLC.

[0061] The mixed solution was added into 1000 mL of distilled water, ultrasonically dispersed, filtered, washed 3 times with 100 mL of deionized water, extracted 3 times with 100 mL of methanol, filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 0.948 g (3.431 mmol) of 1,3,5-triimidazolylbenzene as a white solid with a yield of 85.8%.

[0062] 1 H NMR (400MHz, [d6]DMSO): δ8.55(s,3H,N-CH-N),8.03(s,3H,imidazole-H),7.96(s,3H,Ar-H),7.18ppm(s,3H,imidazole-H). 13 C NMR (100MHz, [d6]DMSO): δ139.54 (Ar-CN), 136.57 (NCN), 130.56 (imizazole-C), 118.76 (Ar-CH), 109.76ppm (imidazole-C). MS (EI): m / z (%) 276 (100) [M] + .Anal.Calcd (%): C, 65.22; H, 4.32; N, 30.43. Found: C, 65.27; H, 4.26; N, 30.35.

[0063] Wherein, the chemical structural formula of 1,3,5-triimidazolylbenzene is:

[0064]

[0065] S2. Dissolve 0.037 g (0.134 mmol) of 1,3,5-triimidazolylbenzene and 0.059 g (0.224 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 120 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed with DMF and 2 mL of ethanol 5 times, and vacuum dried at 60 °C for 12 h to obtain 75 mg of imidazolium salt polymer adsorbent, ImIP3, with a yield of 83.3%.

[0066] FT-IR(KBr,cm -1 ):3415(b),3060(b),2844(w),1622(s),1548(s),1493(w),1450(w),14 19(w),1368(w),1226(m),1188(m),1101(m),1018(w),868(w),777(m).

[0067] Example 4

[0068] A method for preparing an imidazolium salt polymer adsorbent is the same as the preparation method of Example 1, except that 1,3,5-tris-(4-bromophenyl)benzene in S1 is replaced by tris-(4-bromophenyl)amine, comprising the following steps:

[0069] S1. Add 1.93 g (4 mmol) of tri-(4-bromophenyl)amine, 8.17 g (120 mmol) of imidazole, 10 g (72 mmol) of K2CO3 and 0.1 g (0.4 mmol) of CuSO 4. 5H2O, heated at 150℃ for 48h, melted into a dark red solution, and the reaction was complete after monitoring by TLC.

[0070] The mixture was added to 1000 mL of distilled water, ultrasonically dispersed, filtered, washed three times with 100 mL of deionized water, extracted three times with 100 mL of methanol, filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 1.538 g (3.468 mmol) of tri-(4-imidazolylphenyl)amine as a white solid with a yield of 86.7%.

[0071] 1 H NMR (400MHz, DMSO-d6): δ = 8.19 (s, 3H, N-CH-N), 7.69 (s, 3H, imidazole-H), 7.61 (d, 3 J=8.8Hz,Ar-H),7.18(d, 3 J=8.8Hz,6H,Ar-H),7.10ppm(s,3H,imidazole-H). 13 CNMR (100MHz, DMSO-d6): δ = 145.3 (Ar-C), 135.4 (NCN), 132.3 (Ar-C), 129.7 (imidazole-C), 124.7 (Ar-C), 121.9 (Ar-C), 118.0ppm (imidazole-C). HRMS (ESI, positive ions):m / z=444.1927(calcd for[M+H] + =444.1931). Anal. Calcd (%): C, 71.66; H, 4.90; N, 21.67. Found: C, 71.35; H, 5.03; N, 22.01.

[0072] Wherein, the chemical structural formula of tri-(4-imidazolylphenyl)amine is:

[0073]

[0074] S2. Dissolve 0.060 g (0.134 mmol) of tri-(4-imidazolylphenyl)amine and 0.059 g (0.224 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 120 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed with DMF and 2 mL of ethanol 5 times, and vacuum dried at 60 °C for 12 h to obtain 98 mg of imidazolium salt polymer adsorbent, ImIP4, with a yield of 87.1%.

[0075] FT-IR(KBr,cm -1 ):3415(b),3060(b),2829(vw),1600(m),1549(s),1512(s),1419(w),1328(s),1291 (s),1226(s),1191(s),1081(s),1021(w),970(m),837(s),726(s),621(m),545(m).

[0076] Example 5

[0077] A method for preparing an imidazolium salt polymer adsorbent, wherein the molar ratio of 1,3,5-tris-(4-bromophenyl)benzene to imidazole in S1 is replaced from 1:30 to 1:3, and the molar ratio of 1,3,5-tris-(4-imidazolylphenyl)benzene to 1,4-di(bromomethyl)benzene in S2 is replaced from 1:1.67 to 1:1, comprising the following steps:

[0078] S1. Add 0.543 g (1 mmol) of 1,3,5-tris-(4-bromophenyl)benzene, 0.204 g (30 mmol) of imidazole, 2.480 g (18 mmol) of K2CO3 and 0.050 g (0.2 mmol) of CuSO 4. 5H2O, heated at 180℃ for 72h, melted into a dark red solution, and the reaction was complete after TLC monitoring.

[0079] The mixed solution was added into 1000 mL of distilled water, ultrasonically dispersed, filtered, washed 3 times with 100 mL of deionized water, extracted 3 times with 100 mL of methanol, filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 1,3,5-tri-(4-imidazolylphenyl)benzene as a white solid.

[0080] S2. Dissolve 0.069 g (0.134 mmol) of 1,3,5-tris-(4-imidazolylphenyl)benzene and 0.035 g (0.134 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 140 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed with DMF and 2 mL of ethanol 5 times, and vacuum dried at 60 °C for 12 h to obtain an imidazolium salt polymer adsorbent.

[0081] Example 6

[0082] A method for preparing an imidazolium salt polymer adsorbent is the same as the preparation method of Example 1, except that the molar ratio of 1,3,5-tris-(4-bromophenyl)benzene to imidazole in S1 is replaced from 1:30 to 1:100, and the molar ratio of 1,3,5-tris-(4-imidazolylphenyl)benzene to 1,4-di(bromomethyl)benzene in S2 is replaced from 1:1.67 to 1:3, comprising the following steps:

[0083] S1. Add 0.543 g (1 mmol) of 1,3,5-tris-(4-bromophenyl)benzene, 6.8 g (30 mmol) of imidazole, 2.480 g (18 mmol) of K2CO3 and 0.050 g (0.2 mmol) of CuSO 4. 5H2O, heated at 60℃ for 12h, melted into a dark red solution, and the reaction was complete after monitoring by TLC.

[0084] The mixed solution was added into 1000 mL of distilled water, ultrasonically dispersed, filtered, washed 3 times with 100 mL of deionized water, extracted 3 times with 100 mL of methanol, filtered with diatomaceous earth, and vacuum dried after removing the solvent to obtain 1,3,5-tri-(4-imidazolylphenyl)benzene as a white solid.

[0085] S2. Dissolve 0.069 g (0.134 mmol) of 1,3,5-tris-(4-imidazolylphenyl)benzene and 0.106 g (0.402 mmol) of 1,4-dibromomethylbenzene in 3 mL of DMF, and react at 60 °C for 24 h under argon atmosphere; after the reaction solution is cooled to room temperature, it is filtered, washed 5 times with DMF and 2 mL of ethanol, and vacuum dried at 60 °C for 2 h to obtain an imidazolium salt polymer adsorbent.

[0086] The imidazolium salt polymer adsorbents prepared in Examples 1 to 4 of the present invention are used as examples to adsorb different anionic pollutants in wastewater, and the saturated adsorption amount and adsorption rate of the imidazolium salt polymer adsorbents prepared in Examples 1 to 4 are studied. The specific application method is as follows:

[0087] Application method:

[0088] a. 15 mg of the imidazolium salt polymer adsorbent of Example 1 was added to a 75 mL aqueous solution with an anion concentration of 5.13 × 10 -4 mol / L aqueous solutions of different types of anionic pollutants were stirred at room temperature and monitored every 5 minutes until adsorption equilibrium was reached. The saturated adsorption amount and adsorption rate of anionic pollutants in aqueous solutions of different types of anionic pollutants by the imidazolium salt polymer adsorbent of Example 1 were calculated by referring to the standard curve. The test results are shown in Table 1.

[0089] b. 15 mg of the imidazolium salt polymer adsorbent prepared in Examples 1 to 4 was added to a volume of 75 mL and a concentration of 5.13 × 10 -4 mol / L potassium dichromate aqueous solution, stirred at room temperature, and monitored every 5 minutes until adsorption equilibrium was reached. The saturated adsorption amount and adsorption rate of potassium dichromate in water were calculated by referring to the standard curve. The test results are shown in Table 2.

[0090] c. 3 mg of the imidazolium salt polymer adsorbent of Example 1 was added to a 10 mL aqueous solution of potassium dichromate at a concentration of 1.71 × 10 -4 mol / L, a series of potassium dichromate aqueous solutions with a pH of 2 to 14. After stirring at room temperature for 5 minutes, the absorbance of the solution was monitored by UV-visible spectroscopy, and the capture efficiency of the material for dichromate in water was calculated in combination with the standard curve. The results are shown in Table 3.

[0091] d. 3 mg of the imidazolium salt polymer adsorbent of Example 1 was added to a volume of 10 mL and a potassium dichromate concentration of 1.71 × 10 -4 mol / L aqueous solution, wherein the aqueous solution contains a concentration of 1.71×10 -3 mol / L F - , Cl - Br - ,I - 、SO4 2- and NO3 - After stirring at room temperature for 5 minutes, the absorbance of the solution was monitored by UV-visible spectroscopy, and the capture efficiency of the material for dichromate in water was calculated in combination with the standard curve. The results are shown in Table 4.

[0092] Table 1 Adsorption of ImIP1 prepared in Example 1 in aqueous solutions of different types of anionic pollutants

[0093] Anionic pollutants Saturated adsorption capacity (mg / g) Adsorption rate (mg / gmin) <![CDATA[K2Cr2O7]]> 423 75 <![CDATA[K2CrO4]]> 350 62 <![CDATA[KMnO4]]> 430 70 <![CDATA[AsH2KO4]]> 443 81 <![CDATA[K3PO4]]> 332 56

[0094] The results in Table 1 show that the ImIP1 prepared in Example 1 has excellent performance in terms of saturated adsorption capacity and adsorption rate in different types of anionic pollutant aqueous solutions, especially for the highly toxic K2Cr2O7 and AsH2KO4, the saturated adsorption capacity exceeds 400 mg / g, and the adsorption rate exceeds 70 mg / g min.

[0095] Table 2 Adsorption of potassium dichromate in aqueous solution by imidazolium salt polymer adsorbents prepared in Examples 1 to 4

[0096] Imidazolium salt polymer adsorbent Saturated adsorption capacity (mg / g) Adsorption rate (mg / gmin) ImIP1 423 75 ImIP2 420 90 ImIP3 430 70 ImIP4 411 30

[0097] The results in Table 2 show that the imidazolium salt polymer adsorbents prepared in Examples 1 to 4 have slightly different adsorption properties for potassium dichromate in aqueous solution. Specifically, all adsorbents showed a high saturated adsorption capacity ranging from 411 mg / g to 430 mg / g, which indicates that the imidazolium salt polymer adsorbents prepared in Examples 1 to 4 can effectively adsorb potassium dichromate from aqueous solution. Among them, ImIP3 has the highest saturated adsorption capacity, reaching 430 mg / g, while ImIP4 has a relatively low saturated adsorption capacity of 411 mg / g.

[0098] In terms of adsorption rate, ImIP2 has the fastest adsorption rate, reaching 90 mg / g, which means that ImIP2 can achieve a higher adsorption amount in a shorter time. On the contrary, ImIP4 has the slowest adsorption rate, only 30 mg / g, which means that it takes longer to achieve the ideal adsorption effect in practical applications. The adsorption rates of ImIP1 and ImIP3 are at the middle level, at 75 mg / g and 70 mg / g, respectively.

[0099] Table 3 Adsorption of ImIP1 prepared in Example 1 in potassium dichromate aqueous solutions at different pH values

[0100] pH 2 4 6 8 10 12 Capture rate (%) 96.9 95.4 96.3 97.5 97.2 51.4

[0101] The results in Table 3 show that the capture efficiency of the ImIP1 adsorbent prepared in Example 1 in potassium dichromate aqueous solutions with different pH values ​​shows significant differences. Specifically, when the pH value of the solution is in the range of 2 to 10, the capture efficiency of ImIP1 for potassium dichromate is extremely high, and is maintained above 95%. In particular, under the condition of pH 8, the capture efficiency reaches a peak of 97.5%. However, when the pH is 12, the capture efficiency of ImIP1 for potassium dichromate drops to 51.4%. This significant change is mainly due to two reasons: First, under strong alkaline conditions, some Cr2O7 2- Converted to CrO4 2-Although the two anions have the same unit charge, the increase in the number of anions undoubtedly intensifies the competition in the adsorption process, which leads to a decrease in the capture efficiency. Secondly, under strong alkaline conditions, the hydrogen atoms at the C2 position of some imidazolium salt units in ImIP1 undergo deprotonation reaction, which weakens the overall positive charge of ImIP1, thereby weakening the adsorption capacity of ImIP1 to negatively charged potassium dichromate ions, resulting in a significant decrease in the capture rate.

[0102] Table 4 Adsorption of ImIP1 prepared in Example 1 in aqueous potassium dichromate solutions with different interfering ions

[0103] Interfering ions <![CDATA[F - ]]> <![CDATA[Cl - ]]> <![CDATA[Br - ]]> <![CDATA[I - ]]> <![CDATA[SO4 2- ]]> <![CDATA[NO3 - ]]> Capture rate (%) 98.5 94.6 96.0 76.4 88.4 80.2

[0104] Combine Table 4 with Figure 7 The results show that in the presence of multiple interfering ions, ImIP1 has excellent stability in capturing potassium dichromate. - , Cl - and Br - When these common interfering ions were present, even if the concentration of these interfering ions was 10 times that of potassium dichromate, the capture rate of potassium dichromate by ImIP1 remained at a high level of 94.6% to 98.5%. This shows that the presence of these interfering ions has almost no significant effect on the adsorption performance of ImIP1, and its ability to capture potassium dichromate remains strong. - In the presence of , the capture rate of potassium dichromate by ImIP1 decreased to 76.4%, but this value still exceeded the performance of many traditional adsorbents under the same conditions, reflecting the relative advantages of ImIP1 under specific conditions. 2- and NO3 - ImIP1 also showed good anti-interference ability, with capture rates as high as 88.4% and 80.2% respectively.

[0105] observe Figure 3 (a) and Figure 3 It can be seen in (b) that both ImIP1 prepared in Example 1 and ImIP2 prepared in Example 2 exhibit a regular spherical structure of 2 μm to 5 μm under a scanning electron microscope, which helps to increase the specific surface area and thus improve the adsorption rate.

[0106] observe Figure 4 (a) and Figure 4 (b) shows that both ImIP1 prepared in Example 1 and ImIP2 prepared in Example 2 have good thermal stability and can maintain the stability of the molecular structure of the imidazolium salt polymer adsorbent at a temperature below 354°C.

[0107] Depend on Figure 5 From (a), (b), and (c) in Example 1, it can be seen that ImIP1 prepared in Example 1 and ImIP2 prepared in Example 2 are composed of four elements, namely, C, H, N, and Br, and also contain O, indicating that ImIP1 and ImIP2 have strong water absorption. Figure 5 (d) in the figure shows that both ImIP1 prepared in Example 1 and ImIP2 prepared in Example 2 contain abundant bromide ions as counter anions. Using the ion exchange mechanism, the imidazolium salt polymer adsorbent of the present invention can effectively adsorb anionic pollutants. The higher the bromide ion content, the greater the amount of anionic pollutants adsorbed by ion exchange in theory.

[0108] Figure 6 The results show that ImIP1 prepared in Example 1 and ImIP2 prepared in Example 2 both have excellent capture efficiency for potassium dichromate at a pH of 2 to 10.

[0109] In order to verify the practical applicability of the imidazolium salt polymer adsorbent, a column chromatography experiment was carried out using the imidazolium salt polymer adsorbent prepared in Example 1 as a sample. The specific operation method is: 25 mL of 1.7 mM potassium dichromate solution is passed through a chromatography column filled with ImIP1, such as Figure 8 As shown in (a) in .

[0110] observe Figure 8 (a) It was found that more than 99.9% of the dichromate was adsorbed after a single pass. To ensure the stability and reliability of the system, a large amount of water was passed through the column that had been treated with potassium dichromate solution. It was found that the captured dichromate was firmly retained in the column and no dichromate ions were detected in the effluent solution, indicating that it was effectively captured in ImIP1. ImIP1, which adsorbed a large amount of dichromate, can be easily regenerated by flushing with a high-concentration NaCl aqueous solution. Observation Figure 8 (b) It was found that more than 99% of the dichromate was recovered by regenerating the column with 1.7 M NaCl aqueous solution. Figure 8 (c) It was concluded that after 10 consecutive cycles, there was no significant loss in the adsorption efficiency of potassium dichromate by the imidazolium salt polymer adsorbent.

[0111] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing an imidazolium salt polymer adsorbent, characterized in that: The following steps are involved: A polybrominated phenyl organic compound, imidazole, a base and a catalyst are mixed, and under the action of the catalyst and the base, the bromine atom in the polybrominated phenyl organic compound and the nitrogen atom in the imidazole molecule undergo a nucleophilic substitution reaction to obtain a tri-imidazolyl organic monomer; wherein the molar ratio of the polybrominated phenyl organic compound to the imidazole is 1:3 to 100; The triimidazolyl organic monomer and 1,4-di(bromomethyl)benzene are dissolved in an organic solvent, and the imidazole nitrogen atom in the triimidazolyl organic monomer and the bromomethyl carbon atom in 1,4-di(bromomethyl)benzene are subjected to a quaternization reaction to obtain an imidazolium salt polymer adsorbent.

2. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The molar ratio of the polybrominated phenyl organic compound to the imidazole is 1:

30.

3. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The conditions for the nucleophilic substitution reaction are: reacting at 60°C to 180°C for 12h to 72h.

4. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The molar ratio of the triimidazolyl organic monomer to 1,4-di(bromomethyl)benzene is 1:1-3.

5. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The conditions for the quaternization reaction are: reacting at 60°C to 140°C for 2h to 24h.

6. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The polybrominated phenyl organic compound is selected from 1,3,5-tris(4-bromophenyl)benzene, 2,4,6-tris-(4-bromophenyl)-1,3,5-triazine, 1,3,5-tribromobenzene or tris-(4-bromophenyl)amine.

7. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The catalyst is selected from at least one of copper sulfate, copper carbonate, copper acetate and cuprous iodide, and the added amount of the catalyst is 0.1% to 5% of the molar amount of the polybrominated phenyl organic compound.

8. The method for preparing an imidazolium salt polymer adsorbent according to claim 1, characterized in that: The base is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide and potassium tert-butoxide, and the amount of the base added is 1 to 50 times the molar amount of the polybrominated phenyl organic compound.

9. An imidazolium salt polymer adsorbent prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The imidazolium salt polymer adsorbent contains imidazolium salt units.

10. Use of the imidazolium salt polymer adsorbent according to claim 9 in preparing an adsorbent for anionic pollutants in water, characterized in that: The anionic contaminant is selected from chromate, dichromate, arsenate, phosphate or permanganate.

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