A preparation method of an ionic covalent organic polymer and its application in adsorbing ReO4 in an alkaline environment - Application

Abstract

A preparation method of an ionic covalent organic polymer, comprising the following steps: (1) Using mesitylene as an initial raw material to synthesize 1,3,5-tribromo-2,4,6-trimethylbenzene; (2) Using 1,3,5-tribromo-2,4,6-trimethylbenzene as a raw material to synthesize 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene; (3) Using 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene as a raw material to synthesize 1,3,5-tetra(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene; (4) Using 1,3,5-tetra(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as a raw material to synthesize iCOP-Br; (5) Performing ion exchange on iCOP-Br to obtain iCOP. The ionic covalent organic polymer is used for capturing ReO4 in water ‑ , which has advantages such as good stability and fast adsorption kinetics, and realizes the adsorption of ReO4 under highly alkaline conditions ‑ .

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and specifically relates to a preparation method of an ionic covalent organic polymer and its application in adsorbing ReO4 - in an alkaline environment. Background Art

[0002] Rhenium is one of the most valuable rare metals in the world. Due to its high melting point and good ductility, it has a wide range of applications in the aerospace and catalytic fields. Currently, most rhenium is produced in smelting wastewater. However, industrial wastewater has complex conditions, such as high alkalinity and low rare earth element concentration (less than 40 mg / L), which makes it very challenging to efficiently recover rhenium. Adsorption materials reported for capturing ReO4 - mainly include metal-organic frameworks (MOFs), porous carbon materials, ion exchange resins, covalent organic frameworks (COFs), etc. Due to the lack of high stability, fast adsorption kinetics, high adsorption capacity, etc., it is difficult to apply them to actual work.

[0003] Ionic covalent organic polymers have advantages such as good stability, good radiation resistance, and easy functionalization, and are one of the ideal materials for capturing ReO4 - Currently, a large number of imidazole-based cationic organic polymers have been used for the adsorption of ReO4 - However, the active sites of their imidazole groups are easily affected by alkalinity, which limits their practical applications under extreme conditions. Therefore, there is an urgent need to develop an ionic covalent organic polymer with high stability, high adsorption capacity, and fast adsorption kinetics. Summary of the Invention

[0004] In order to overcome the above problems of the prior art, the purpose of the present invention is to provide a preparation method of an ionic covalent organic polymer and its application in highly alkaline adsorption of ReO4 - The ionic covalent organic polymer material prepared by the present invention has advantages such as high stability, high adsorption capacity, and fast adsorption kinetics, and is an ideal material for adsorbing ReO4 - .

[0005] The synthesis route of the porous ionic covalent organic polymer of the present invention is as follows:

[0006]

[0007] Specifically, in the first aspect of the present invention, a preparation method of an ionic covalent organic polymer is provided, including the following steps:

[0008] (1) Using mesitylene as the initial raw material to synthesize 1,3,5-tribromo-2,4,6-trimethylbenzene;

[0009] (2) Using 2,4,6-tribromo-mesitylene as a raw material to synthesize 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene;

[0010] (3) Using 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene as a raw material to synthesize 1,3,5-tetra(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene;

[0011] (4) Using 1,3,5-tetra(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as a raw material to synthesize iCOP-Br

[0012] (5) Performing ion exchange on iCOP-Br to obtain iCOP, which is the ionic covalent organic polymer of the present invention.

[0013] Preferably, in step (1), the reaction of synthesizing 1,3,5-tribromo-2,4,6-trimethylbenzene using mesitylene as the initial raw material is to put aluminum bromide and liquid bromine into a three-necked flask at 0 °C, then slowly add 1,3,5-trimethylbenzene, heat the mixture to room temperature and stir. After the reaction is completed, add water, filter the crude product, wash it with water and recrystallize it with CHCl3 to obtain colorless fine needles.

[0014] Preferably, in step (2), the reaction of synthesizing 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene using 2,4,6-tribromo-mesitylene as a raw material is to dissolve 1,3,5-tribromo-2,4,6-trimethylbenzene in 1,2-dibromoethane, then add liquid bromine and stir at room temperature. Immediately heat the mixture to reflux. After the reaction is completed, cool it to room temperature, filter the crude product, wash it with 1,2-dibromoethane and recrystallize it with CHCl3 to obtain a colorless powder.

[0015] Preferably, in step (3), the reaction of synthesizing 1,3,5-tetra(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene using 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene as a raw material is to dissolve 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene in cold anhydrous tetrahydrofuran, then add 1-vinylimidazole, heat to reflux. After the reaction is completed, cool it to room temperature, filter, wash with ethyl acetate, and dry the obtained solid.

[0016] Preferably, in step (4), the reaction for synthesizing iCOP-Br using 1,3,5-tris(1'-methyl-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as a raw material is as follows: dissolve 1,3,5-tris(1'-methyl-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene in ethanol and water, then add azobisisobutyronitrile and heat under reflux. After the reaction is completed, filter the solid, then wash it with ethanol and water, and dry the solid.

[0017] Preferably, in step (5), the reaction for obtaining iCOP by ion exchange of iCOP-Br is as follows: disperse iCOP-Br in a saturated aqueous sodium chloride solution and stir. After the reaction is completed, filter the solid, then wash it with water and ethanol, and dry the solid to obtain iCOP.

[0018] In the second aspect of the present invention, there is provided a method for capturing ReO4 in water using the ion covalent organic polymer prepared in the first aspect of the present invention. - The method is to add the above-mentioned ion covalent organic polymer to an aqueous solution containing ReO4 - for adsorbing ReO4 - , and the aqueous solution containing ReO4 - is a 3M NaOH aqueous solution containing rhenium.

[0019] In the third aspect of the present invention, there is provided an application of the ion covalent organic polymer prepared in the first aspect of the present invention and the method in the second aspect for capturing ReO4 in water. -

[0020] In a highly alkaline solution, the content of OH - ions is very high, and the imidazole-based active sites are easily attacked by OH - . Therefore, to achieve the adsorption of ReO4 in a highly alkaline solution - , it is still necessary to protect the imidazole groups. Based on this, 1,3,5-tris(1'-methyl-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene is selected to synthesize a cationic organic polymer with a novel structure, which has advantages such as good stability and fast adsorption kinetics, and realizes the adsorption of ReO4 under highly alkaline conditions. - .

[0021] The iCOP prepared in the present invention has many imidazole-based active sites for ion exchange adsorption of ReO4 - . By introducing bromine branches near the imidazole-based active sites, the attack of OH - on the active sites is reduced, thereby enhancing its alkali stability. The results of ultraviolet spectroscopy show that under highly alkaline conditions, the adsorption kinetics and adsorption capacity of iCOP are better than those of some commercially available strongly alkaline resins, and it is an ideal material for adsorbing ReO4 under alkaline conditions. - ​ Description of the Drawings

[0022] Figure 1 : X-ray diffraction pattern of the porous ionic covalent organic polymer;

[0023] Figure 2 : Infrared spectrum of the porous ionic covalent organic polymer;

[0024] Figure 3 : Solid-state nuclear magnetic 13 C spectrum of the porous ionic covalent organic polymer;

[0025] Figure 4 : Scanning electron micrograph of the porous ionic covalent organic polymer;

[0026] Figure 5 : Kinetic comparison of the porous ionic covalent organic polymer with different commercial materials in 3M NaOH / ReO4 - aqueous solution;

[0027] Figure 6 : Saturated adsorption isotherm diagram of the porous ionic covalent organic polymer in 3M NaOH / ReO4 - aqueous solution; Detailed Description of the Embodiments

[0028] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0029] As described in the background art, cationic organic polymers have advantages such as good stability, good radiation resistance, and easy functionalization, and are one of the ideal materials for capturing ReO4 - under highly alkaline conditions. However, the active sites of most cationic organic polymers are often attacked by OH - , resulting in poor alkali stability. Based on this, there is an urgent need to develop iCOP materials with high stability for ReO4 - capture.

[0030] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with reference to specific embodiments.

[0031] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0032] Example 1 Preparation of the Ionic Covalent Organic Polymer of the Present Invention

[0033] (1) The method for synthesizing 1,3,5-tribromo-2,4,6-trimethylbenzene using mesitylene as the starting material is as follows:

[0034] First, the flask should be equipped with an exhaust device. Subsequently, aluminum bromide (0.27 g, 0.001 mol) and liquid bromine (96 g, 0.6 mol) are placed in a 1 L three-necked flask under the condition of 0 °C. Next, mesitylene (12 g, 0.1 mol) is slowly added within 1.5 hours. Then, the mixture is heated to room temperature and stirred for 2 days. After the reaction is completed, 50 mL of water is added, and the crude product is filtered, washed with water, and recrystallized with CHCl₃ to obtain colorless fine needles.

[0035] (2) The method for synthesizing 1,3,5-tris(bromomethyl)-2,4,6-tribromobenzene using 2,4,6-tribromomesitylene as the raw material is as follows:

[0036] Dissolve 1,3,5-tribromo-2,4,6-trimethylbenzene (35.7 g, 0.1 mol) in 150 mL of 1,2-dibromoethane, and then add liquid bromine (48 g, 0.3 mol). Stir at room temperature for 30 minutes. Immediately heat the mixture to reflux for 20 hours. After the reaction is completed, cool to room temperature. Filter the crude product, wash it with a small amount of 1,2-dibromoethane, and recrystallize with CHCl₃ to obtain a colorless powder.

[0037] (3) The method for synthesizing 1,3,5-tetrakis(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene using 1,3,5-tris(bromomethyl)-2,4,6-tribromobenzene as the raw material is as follows:

[0038] Dissolve 1,3,5-tris(bromomethyl)-2,4,6-tribromobenzene (17.52 g, 20 mmol) in cold anhydrous tetrahydrofuran, and then add 1-vinylimidazole (13.26 g, 72 mmol). Heat to reflux for 24 hours. After the reaction is completed, cool to room temperature. Filter and wash with ethyl acetate. Dry the obtained solid.

[0039] (4) The method for synthesizing iCOP-Br using 1,3,5-tetrakis(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as the raw material is as follows:

[0040] Take 1,3,5-tetrakis(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene (1 g) and dissolve it in a mixture of ethanol and water with a ratio of (3:1). Then add azobisisobutyronitrile (0.1 g) and heat to reflux for 24 hours. After the reaction is completed, filter the solid, and then wash it with ethanol and water. Dry the solid.

[0041] (5) The method for ion exchange using iCOP-Br is as follows:

[0042] Disperse iCOP-Br (1 g) into a saturated aqueous sodium chloride solution and stir for 24 hours. After the reaction is completed, filter the solid, and then wash it with water and ethanol. Dry the solid to obtain iCOP.

[0043] The structure of iCOP can be determined by X-ray powder diffraction pattern (PXRD). Below, the porous ion covalent organic polymer prepared in Example 1 will be described. Figure 1-4 for illustration.

[0044] As Figure 1 shown, a strong peak appears at 24° in the PXRD spectrum, indicating that iCOP is an amorphous phase, similar to most porous ion organic polymers. The iCOP was characterized by infrared spectroscopy. As Figure 2 shown, the peak at 1113 cm -1 in the infrared spectrum of iCOP is attributed to the imidazole functional group. 13 The peaks in the Figure 3 CNMR spectrum all correspond to the relevant carbon atoms in the expected structure of iCOP. As 13 shown, the peaks appearing at 124 and 135 ppm are attributed to the carbons on the imidazole ring, while the peaks appearing at 40 and 56 ppm are attributed to the carbons on the methylene group. The results of the FT-IR and Figure 4 CNMR spectra indicate that the porous ion organic polymer iCOP was successfully synthesized by this method. As

[0045] Example 2 The ion covalent organic polymer of the present invention for capturing ReO4 in water -

[0046] Add the ion covalent organic polymer prepared in Example 1 above to the NaOH aqueous solution added with ReO4 - respectively for adsorption kinetics and isotherm experiments.

[0047] Isotherm: The content of rhenium added in the 3M NaOH aqueous solution is 10 - 150 ppm, and the addition amount of iCOP is 0.5 g / L.

[0048] Filter the adsorbed suspension with a 0.22 μm microporous filter membrane and measure the absorbance with a UV spectrophotometer.

[0049] Kinetics: The content of rhenium added in the 3M NaOH aqueous solution is 28 ppm, and the addition amount of iCOP is 1 g / L. The solution is taken out regularly, the suspension is filtered with a 0.22 μm microporous filter membrane, and the absorbance is measured with a UV spectrophotometer.

[0050] The technical effect of the ionic covalent organic polymer of the present invention shown in Example 2 in capturing ReO4 in water - can be described in combination with the attached Figure 5-6 for illustration.

[0051] As Figure 5 shown, the adsorption kinetics of iCOP and commercial resins. The content of rhenium added in 3M NaOH aqueous solution is 28 ppm, and the addition amounts of iCOP and two commercial resins are 1 g / L. The solution is taken out regularly and completed within one hour. The suspension is filtered through a 0.22 μm microporous membrane, and the absorbance is measured with a UV spectrophotometer.

[0052] The adsorption isotherm experiment of iCOP. The content of rhenium added in the NaOH aqueous solution is 10 - 150 ppm, and the addition amount of iCOP is 0.5 g / L. The suspension after adsorption is filtered through a 0.22 μm microporous membrane, and the absorbance is measured with a UV spectrophotometer. As Figure 6 shown, the adsorption isotherm of iCOP is 110 mg / g.

[0053] Those skilled in the art will readily conceive of other embodiments of the present disclosure upon considering the specification and practice disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims of this application.

Claims

1. A preparation method of an ionic covalent organic polymer, comprising the following steps: (1) Using mesitylene as the initial raw material to synthesize 1,3,5-tribromo-2,4,6-trimethylbenzene; (2) Using 1,3,5-tribromo-2,4,6-trimethylbenzene as the raw material to synthesize 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene; (3) Using 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene as the raw material to synthesize 1,3,5-tris(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene; (4) Using 1,3,5-tris(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as the raw material to synthesize iCOP-Br; (5) Performing ion exchange on iCOP-Br to obtain iCOP; (6) The reagents used in the above experiments are analytical pure products; In the reaction of using 1,3,5-tris(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene as the raw material to synthesize iCOP-Br in step (4), take 1,3,5-tris(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene and dissolve it in ethanol and water, then add azobisisobutyronitrile and heat under reflux. After the reaction is completed, filter the solid, then wash it with ethanol and water, and dry the solid; In the reaction of performing ion exchange on iCOP-Br to obtain iCOP in step (5), take iCOP-Br and disperse it in a saturated sodium chloride aqueous solution and stir. After the reaction is completed, filter the solid, then wash it with water and ethanol, and dry the solid to obtain iCOP.

2. According to the preparation method described in claim 1, in the reaction of using mesitylene as the initial raw material to synthesize 1,3,5-tribromo-2,4,6-trimethylbenzene in step (1), put aluminum bromide and liquid bromine into a three-necked flask under the condition of 0 °C, then slowly add 1,3,5-trimethylbenzene, heat the mixture to room temperature and stir. After the reaction is completed, add water, filter the crude product, wash it with water and recrystallize it with CHCl3 to obtain colorless fine needles.

3. According to the preparation method described in claim 1, in the reaction of using 1,3,5-tribromo-2,4,6-trimethylbenzene as the raw material to synthesize 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene in step (2), dissolve 1,3,5-tribromo-2,4,6-trimethylbenzene in 1,2-dibromoethane, then add liquid bromine and stir at room temperature. Immediately heat the mixture under reflux. After the reaction is completed, cool it to room temperature, filter the crude product, wash it with 1,2-dibromoethane and recrystallize it with CHCl3 to obtain a colorless powder.

4. According to the preparation method described in claim 1, in step (3), the reaction of synthesizing 1,3,5-tris(1'-methylene-3'-vinylimidazolium bromide)-2,4,6-tribromobenzene using 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene as the raw material is as follows: dissolve 1,3,5-tribromo-2,4,6-tris(bromomethyl)benzene in cold anhydrous tetrahydrofuran, then add 1-vinylimidazole, heat under reflux, cool to room temperature after the reaction is completed, filter, wash with ethyl acetate, and dry the obtained solid.

5. A method for capturing ReO4 in water using the ion covalent organic polymer obtained by any one of the preparation methods of claims 1-4 - is to add the said ion covalent organic polymer into an aqueous solution containing ReO4 - for adsorbing ReO4 - .

6. The method for capturing ReO4 in water by the ion covalent organic polymer according to claim 5 - , wherein the aqueous solution containing ReO4 - is a 3M NaOH aqueous solution containing ReO4 - .

7. Use of the ion covalent organic polymer prepared by the preparation method according to any one of claims 1-4 for capturing ReO4 in water - in water.

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