Crown ether functionalized Mxene adsorbent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sewage treatment, and provides a crown ether functionalized Mxene adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly, carrying out amino functionalization on Ti3C2Tx by adopting an amino-containing silanization reagent, and then introducing 4-nitrobenzene-15-crown-5 ether on the Ti3C2Tx through a coupling reaction, so as to obtain the crown ether functionalized Mxene adsorbent. The crown ether functionalized Mxene adsorbent prepared by the invention has relatively high adsorption capacity and selectivity to rubidium ions, has unique corrosion resistance, and still shows good stability after rubidium adsorption is completed in a simulated metallurgical wastewater environment; the problem that rubidium and cesium are difficult to separate is effectively solved, selective recovery of rubidium in the metallurgical wastewater can be achieved, and the method has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a crown ether functionalized Mxene adsorbent and a preparation method and application thereof. Background Art

[0002] Rubidium (Rb), cesium (Cs), and their compounds, due to their unique physicochemical properties, have been widely used in novel energy conversion models, attracting the attention of the global energy community. For example, thermionic power generation utilizes the principle of a secondary vacuum tube and the thermionic activity of Rb(I) plasma to directly convert thermal energy into electrical energy. Furthermore, due to its excellent optical, electrical, thermal, physical, and chemical properties, Rb(I) is an important raw material in lasers, quantum sensors, thermoelectromagnetic materials, specialty glasses, and pharmaceuticals. Furthermore, Rb, Cs, and their compounds also play an important role in modern industry, aerospace, and defense.

[0003] The metallurgical industry generates large amounts of wastewater containing Rb and Cs during smelting processes. The enrichment or separation of Rb and Cs has become a challenging and hot topic. Over the past few decades, researchers have developed and evaluated various methods for capturing Rb and Cs from wastewater, such as evaporation, precipitation, ion exchange, adsorption, solvent extraction, and membrane separation. Among these, adsorption technology has been recognized as one of the most promising methods for metal ion enrichment due to its simplicity, low cost, and high efficiency. However, most current adsorbents adsorb Rb and Cs simultaneously, making it difficult to achieve the desired separation. Summary of the Invention

[0004] In view of this, the present invention provides a crown ether functionalized Mxene adsorbent and its preparation method and application. The crown ether functionalized Mxene adsorbent provided by the present invention can selectively adsorb Rb, thereby achieving effective separation of Rb and Cs in wastewater.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for preparing a crown ether functionalized Mxene adsorbent comprises the following steps:

[0007] Ti3C2T x The dispersion was mixed with an aminosilane reagent to undergo a silanization reaction to obtain amino-functionalized Ti3C2T x Material;

[0008] The crosslinker, 4-nitrobenzo-15-crown-5 ether, amino-functionalized Ti3C2T x The material and water are mixed to undergo a coupling reaction to obtain a crown ether functionalized Mxene adsorbent.

[0009] Preferably, the Ti3C2T x The preparation method of the dispersion comprises: x After ultrasonic dispersion in alcohol solvent, the supernatant was taken as Ti3C2T x dispersion; the Ti3C2T x The dosage ratio of the Ti3C2T x The dosage ratio of the aminosilane reagent is 1g: (8-15)mL; the ultrasonic dispersion time is 24-48h; the standing temperature is -5-10°C, and the standing time is 6-12h.

[0010] Preferably, the Ti3C2T x The preparation method includes: mixing LiF, hydrochloric acid solution and Ti3AlC2 to perform etching reaction to obtain Ti3C2T x ; The mass ratio of LiF and Ti3AlC2 is 1:(1~2); the concentration of the hydrochloric acid solution is 5~7.5mol / L; the usage ratio of LiF and hydrochloric acid solution is (2~3)g:(20~30)mL; the temperature of the etching reaction is 35~40℃, and the time is 48~72h.

[0011] Preferably, the aminosilane reagent includes one or more of 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and 3-(4-aminomethylphenyl)-aminopropyltriethoxysilane; the temperature of the silanization reaction is 55-65°C and the time is 1-2h.

[0012] Preferably, the crosslinking agent is a dialdehyde crosslinking agent; the amount ratio of the crosslinking agent to 4-nitrobenzo-15-crown-5 ether is 1g:(1-1.5)mL; the amino-functionalized Ti3C2T x The ratio of material and 4-nitrobenzo-15-crown-5 ether is 1 g: (1-4) mL;

[0013] The coupling reaction temperature is 50-60° C., and the reaction time is 10-14 h.

[0014] Preferably, the coupling reaction comprises: dissolving a cross-linking agent and 4-nitrobenzo-15-crown-5 ether in a portion of water to obtain a cross-linking agent-crown ether mixture;

[0015] Functionalizing Ti3C2T with amino groups x The material was dispersed in the remaining water to obtain amino-functionalized Ti3C2T x Material dispersion;

[0016] The amino-functionalized Ti3C2Tx The material dispersion is heated to 50-60°C, and then the amino-functionalized Ti3C2T x The cross-linking agent-crown ether mixed solution is added dropwise to the material dispersion, and after the addition is completed, the mixture is reacted at 50-60° C. for 10-14 hours.

[0017] The present invention also provides a crown ether functionalized Mxene adsorbent prepared by the preparation method described in the above scheme, including amino functionalized Ti3C2T x Materials and coupling on the amino-functionalized Ti3C2T x 4-Nitrobenzo-15-crown-5 ether on the materials.

[0018] The present invention also provides the use of the crown ether functionalized Mxene adsorbent described in the above solution in the selective adsorption of rubidium.

[0019] The present invention also provides a method for separating rubidium and cesium in metallurgical wastewater, comprising the following steps: mixing the metallurgical wastewater and the crown ether functionalized Mxene adsorbent described in the above scheme to selectively adsorb rubidium; the pH value of the metallurgical wastewater is 4-9; and the metallurgical wastewater contains rubidium ions and cesium ions.

[0020] Preferably, after the selective adsorption of rubidium, the process further comprises regenerating the adsorbed crown ether functionalized Mxene adsorbent; the regeneration comprises soaking the adsorbed crown ether functionalized Mxene adsorbent in a regeneration liquid; the regeneration liquid is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.1 to 0.5 mol / L, and the soaking time is 1 to 2 hours.

[0021] The present invention provides a method for preparing a crown ether functionalized Mxene adsorbent, comprising the following steps: x The dispersion was mixed with an aminosilane reagent to undergo a silanization reaction to obtain amino-functionalized Ti3C2T x Materials: Crosslinker, 4-nitrobenzo-15-crown-5 ether, amino-functionalized Ti3C2T x The material and water are mixed to carry out coupling reaction to obtain crown ether functionalized Mxene adsorbent. The present invention first uses an amino-containing silanization reagent to x The amino functionalization was carried out and then Ti3C2T x4-Nitrobenzo-15-crown-5 ether is introduced. The crown ether functionalized Mxene adsorbent prepared by the present invention has a high negative charge, and 4-nitrobenzo-15-crown-5 ether can preferentially adapt to Rb ions, and enhance the electrostatic attraction to Rb ions through the nitro electron-withdrawing effect, thereby achieving selective adsorption of Rb. The results of the embodiment show that the crown ether functionalized Mxene adsorbent prepared by the present invention has a high adsorption capacity and selectivity for Rb, and has unique corrosion resistance. After the adsorption of Rb is completed in a simulated metallurgical wastewater environment, it still shows good stability; the crown ether functionalized Mxene adsorbent prepared by the present invention has the advantages of high efficiency, selectivity, pollution-free and stability, effectively solves the problem of difficult separation of Rb and Cs, can achieve selective recovery of Rb in metallurgical wastewater, and has broad application prospects. DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing a crown ether functionalized Mxene adsorbent, comprising the following steps:

[0023] Ti3C2T x The dispersion was mixed with an aminosilane reagent to undergo a silanization reaction to obtain amino-functionalized Ti3C2T x Material;

[0024] The crosslinker, 4-nitrobenzo-15-crown-5 ether, amino-functionalized Ti3C2T x The material and water are mixed to undergo a coupling reaction to obtain a crown ether functionalized Mxene adsorbent.

[0025] The present invention combines Ti3C2T x The dispersion was mixed with an aminosilane reagent to undergo a silanization reaction to obtain amino-functionalized Ti3C2T x In the present invention, the Ti3C2T x In, T x represents the surface functional group; the Ti3C2T x The method for preparing the dispersion preferably comprises: x After ultrasonic dispersion in alcohol solvent, the supernatant was taken as Ti3C2T x dispersion; the alcohol solvent is preferably ethanol, specifically anhydrous ethanol; the Ti3C2T x The dosage ratio of the Ti3C2T4O4 solvent is preferably (1-1.5) g: (100-200) mL, specifically 1 g: 100 mL, 1.2 g: 120 mL or 1.5 g: 200 mL. xThe dosage ratio of the aminosilane reagent is preferably 1g: (8-15) mL, specifically 1g: 8 mL, 1g: 10 mL or 1g: 15 mL; the ultrasonic dispersion time is preferably 24-48 h, specifically 24 h, 32 h or 48 h; the standing temperature is preferably -5-10 ° C, and the standing time is preferably 6-12 h, specifically 6 h, 8 h or 12 h; after the standing is completed, the supernatant is separated; the present invention removes thick Ti3C2T x , and obtain a uniformly dispersed supernatant.

[0026] In the present invention, the Ti3C2T x The preparation method preferably comprises: mixing LiF, hydrochloric acid solution and Ti3AlC2 to perform etching reaction to obtain Ti3C2T x The mass ratio of LiF to Ti3AlC2 is preferably 1:(1-2), specifically 1:1, 1:1.5 or 1:2; the mesh size of Ti3AlC2 is preferably greater than or equal to 400 mesh; the concentration of the hydrochloric acid solution is preferably 5-7.5 mol / L, specifically 5 mol / L, 6 mol / L or 7.5 mol / L; the amount ratio of LiF to hydrochloric acid solution is preferably 2-3 g:20-30 mL; the temperature of the etching reaction is preferably 35-40 ° C, specifically It can be 35°C, 38°C or 40°C, and the etching reaction time is preferably 48 to 72 hours, specifically 48 hours, 60 hours or 72 hours; the etching reaction is preferably carried out in a polytetrafluoroethylene-lined reactor; the etching reaction is preferably carried out in a constant temperature water bath; in a specific embodiment of the present invention, it is preferred to first add LiF and hydrochloric acid solution to the reactor and stir for 30 minutes to obtain a transparent solution, and then slowly add Ti3AlC2 to the reactor, and then react under constant temperature water bath conditions. During the etching reaction, HF generated by LiF and hydrochloric acid selectively removes the aluminum element in Ti3AlC2, and functional groups such as -OH, -F, and -O in the solution will adhere to the surface of Ti3C2 to form Ti3C2T x .

[0027] After the etching reaction is completed, the present invention preferably centrifuges, washes and dries the obtained reaction solution in sequence; the centrifugal speed is preferably 3500-4500 rpm, and the centrifugal time is preferably 5-10 min; the washing is performed until the pH value of the supernatant reaches 6; the drying is preferably vacuum drying, the vacuum drying temperature is preferably 50-70°C, and the time is preferably 12-16 h.

[0028] In the present invention, the aminosilane reagent preferably includes one or more of 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and 3-(4-aminomethylphenyl)-aminopropyltriethoxysilane, more preferably 3-aminopropyltriethoxysilane; the temperature of the silanization reaction is preferably 55 to 65°C, specifically 55°C, 60°C or 65°C, and the time of the silanization reaction is preferably 1 to 2 hours. In a specific embodiment of the present invention, it is preferred to firstly x The dispersion is heated to 55-65° C., and then an aminosilane reagent is added under stirring, followed by reaction under heat preservation conditions.

[0029] After the silanization reaction is completed, the present invention preferably cools the obtained reaction solution to room temperature and then performs solid-liquid separation to obtain a solid product; the solid product is washed and freeze-dried to obtain amino-functionalized Ti3C2T x Materials; the detergent used in the washing is preferably deionized water; the freeze-drying temperature is preferably -50 to -45°C, and the drying time is preferably 12 to 14 hours.

[0030] Obtain amino-functionalized Ti3C2T x After the material is prepared, the present invention combines a crosslinking agent, 4-nitrobenzo-15-crown-5 ether, amino-functionalized Ti3C2T x The material and water are mixed to carry out a coupling reaction to obtain a crown ether functionalized Mxene adsorbent. In the present invention, the cross-linking agent is preferably a dialdehyde cross-linking agent, and the dialdehyde cross-linking agent preferably includes one or more of glutaraldehyde, o-phthalaldehyde, succinyldialdehyde and furan dicarboxaldehyde, more preferably glutaraldehyde; the amount ratio of the cross-linking agent and 4-nitrobenz-15-crown-5 ether is preferably 1g: (1-1.5)mL, specifically 1g: 1mL, 1g: 1.2mL or 1g: 1.5mL; the amino-functionalized Ti3C2T x The usage ratio of the material and 4-nitrobenzo-15-crown-5 ether is 1g:(1-4)mL, specifically 1g:3mL or 1.3g:4.5mL; the temperature of the coupling reaction is preferably 50-60°C, specifically 50°C, 55°C or 60°C, and the time of the coupling reaction is preferably 10-14h, specifically 10h, 12h or 14h.

[0031] In the present invention, the coupling reaction preferably comprises: dissolving glutaraldehyde and 4-nitrobenzo-15-crown-5 ether in a portion of water to obtain a crosslinker-crown ether mixture; x The material was dispersed in the remaining water to obtain amino-functionalized Ti3C2T x Material dispersion; the amino functionalized Ti3C2T xThe material dispersion is heated to 50-60°C, and then the amino-functionalized Ti3C2T x The crosslinker-crown ether mixture is added dropwise to the material dispersion, and the mixture is reacted at 50-60° C. for 10-14 hours. The ratio of the crosslinker to water in the crosslinker-crown ether mixture is preferably 3 g: (100-120) mL. The amino-functionalized Ti3C2T x Amino-functionalized Ti3C2T in material dispersion x The ratio of material to water is preferably (1-1.3) g: (100-120) mL; the dispersion is preferably carried out under ultrasonic dispersion and mechanical stirring conditions, and the dispersion time is preferably 30 min; the time for adding the crosslinker-crown ether mixture dropwise is preferably 30 min; in a specific embodiment of the present invention, the amino-functionalized Ti3C2T x The material dispersion is heated to 50-60°C and maintained for 1 hour, and then the crosslinker-crown ether mixture is added dropwise.

[0032] After the coupling reaction is completed, the present invention preferably filters the obtained reaction solution to obtain a solid product, washes the solid product and freeze-dries it to obtain a crown ether functionalized Mxene adsorbent; the detergent used for the washing is preferably deionized water; the freeze-drying temperature is preferably -50 to -45°C, and the drying time is preferably 12 to 14 hours.

[0033] The present invention also provides a crown ether functionalized Mxene adsorbent prepared by the preparation method described in the above scheme, including amino functionalized Ti3C2T x Materials and coupling on the amino-functionalized Ti3C2T x 4-Nitrobenzo-15-crown-5 ether on the materials.

[0034] The present invention also provides the use of the crown ether functionalized Mxene adsorbent described in the above solution in the selective recovery of rubidium.

[0035] The present invention also provides a method for separating rubidium and cesium from metallurgical wastewater, comprising the following steps: mixing the metallurgical wastewater with a crown ether-functionalized MXene adsorbent for selective adsorption of rubidium. In the present invention, the pH value of the metallurgical wastewater containing rubidium and cesium is 4 to 9, specifically 4, 5, 6, 7, 8, or 9; the rubidium ion and cesium ion content of the metallurgical wastewater containing rubidium and cesium is preferably 1 to 300 mg / L, and the cesium ion content is preferably 1 to 300 mg / L; the amount of the crown ether-functionalized MXene adsorbent used is preferably 0.5 to 1 g / L, specifically 0.5 g / L, 0.8 g / L, or 1 g / L; the rubidium selective adsorption is preferably performed for 2 to 4 hours at room temperature; and the rubidium selective adsorption is preferably performed under stirring. After the adsorption is completed, the present invention preferably performs solid-liquid separation on the adsorbed feed liquid to obtain the adsorbed crown ether functionalized Mxene adsorbent and the separation liquid; during the adsorption process, the cesium ions are adsorbed onto the crown ether functionalized Mxene adsorbent, and the rubidium ions remain in the liquid phase, thereby achieving the separation of rubidium and cesium.

[0036] In the present invention, after the selective adsorption of rubidium, the adsorbent is preferably regenerated. The regeneration preferably comprises soaking the adsorbed crown ether-functionalized Mxene adsorbent in a regeneration solution. The regeneration solution is preferably a hydrochloric acid solution with a concentration of 0.1 to 0.5 mol / L, and the soaking time is preferably 1 to 2 hours. During the regeneration process, the coordination bond between the cesium ion and the adsorbent is destroyed, thereby releasing the cesium ion into the liquid phase, resulting in a regenerated adsorbent.

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1

[0039] (1) 2 g of LiF was slowly added to a polytetrafluoroethylene-lined reactor containing 20 mL of 5 M HCl solution and mechanically stirred continuously for 30 minutes to obtain a transparent solution. Then, 2 g of 400 mesh Ti3AlC2 was slowly added. The reaction solution was transferred to a constant temperature water bath and heated at 35 ° C for 48 hours to complete the etching of Al. After the reaction was completed, the reaction solution was centrifuged at 3500 rpm for 5 minutes and washed with deionized water (DI) until the pH of the supernatant reached 6.0. The solid product was vacuum dried at 50 ° C for 12 hours to obtain Ti3C2T x .

[0040] (2) 1.0g Ti3C2T x The mixture was dispersed in 100 mL of anhydrous ethanol and ultrasonicated for 24 h. The mixture was placed in a refrigerator for 6 h. The supernatant was transferred to a three-necked flask and heated to 55 ° C. 8 mL of 3-aminopropyltriethoxysilane was added under magnetic stirring and kept warm for 1 h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was separated and washed with water, and then freeze-dried at -50 ° C for 12 h to obtain amino-functionalized Ti3C2T x Material.

[0041] (3) First, 3 g of glutaraldehyde and 3 mL of 4-nitrobenz-15-crown-5 ether were dissolved in 100 mL of deionized water to obtain a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether for storage. Then, 1 g of amino-functionalized Ti3C2T x The material was dispersed into 100 mL of deionized water and ultrasonically dispersed for 30 minutes. The ultrasonic dispersion process was accompanied by continuous mechanical stirring to obtain amino-functionalized Ti3C2T x material dispersion, and then amino-functionalized Ti3C2T x The material dispersion was heated to 50°C and maintained for 1 hour, and then a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether was added dropwise within 30 minutes. After the addition was completed, the mixture was reacted at 50°C for 10 hours. After the reaction was completed, it was filtered with filter paper, and the obtained solid product was washed three times with deionized water. Finally, it was freeze-dried at -50°C for 12 hours to obtain the crown ether functionalized Mxene adsorbent.

[0042] The crown ether functionalized Mxene adsorbent prepared in this example is used to selectively recover rubidium from metallurgical wastewater. The specific steps are as follows:

[0043] Rubidium chloride and cesium chloride were used to prepare simulated metallurgical wastewater containing rubidium and cesium, wherein the contents of rubidium ions and cesium ions were both 100 mg / L. The pH value of the wastewater was adjusted to 4.0 using hydrochloric acid. The crown ether functionalized MXene adsorbent was added to the wastewater to be treated at a ratio of 0.5 g per liter of the wastewater to be treated. The adsorbent was stirred for 2 hours, and the supernatant was removed by centrifugal filtration. The concentrations of rubidium and cesium ions in the supernatant were detected. The recovery rate of rubidium ions was 89%, the rubidium adsorption capacity was 178 mg / g, and the recovery rate of cesium was 2.3%.

[0044] A 0.1 mol / L HCl solution was prepared as the regeneration solution, and the adsorbed crown ether functionalized MXene adsorbent was immersed in the regeneration solution for 1 hour to complete the regeneration, with a regeneration efficiency of 92%.

[0045] Example 2

[0046] (1) 2.5 g of LiF was slowly added to a polytetrafluoroethylene-lined reactor containing 25 mL of 6 M HCl solution and mechanically stirred continuously for 30 min to obtain a transparent solution. Then, 3.75 g of 400 mesh Ti3AlC2 was slowly added. The reaction solution was transferred to a constant temperature water bath and heated at 40 ° C for 60 h to complete the etching of Al. After the reaction was completed, the reaction solution was centrifuged at 4000 rpm for 10 min and washed with deionized water (DI) until the pH of the supernatant reached 6.0. The solid product was vacuum dried at 50 ° C for 14 h to obtain Ti3C2T x .

[0047] (2) 1.2g Ti3C2T x The mixture was dispersed in 120 mL of anhydrous ethanol and ultrasonicated for 30 h. The mixture was placed in a refrigerator for 8 h. The supernatant was transferred to a three-necked flask and heated to 60 ° C. 12 mL of 3-aminopropyltriethoxysilane was added under magnetic stirring and kept warm for 2 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed with water and then freeze-dried at -50 ° C for 12 h to obtain amino-functionalized Ti3C2T x Material.

[0048] (3) First, 3 g of glutaraldehyde and 3.6 mL of 4-nitrobenz-15-crown-5 ether were dissolved in 110 mL of deionized water to obtain a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether for storage. Then, 1.2 g of amino-functionalized Ti3C2T x The material was dispersed in 110 mL of deionized water and ultrasonically dispersed for 30 min. The ultrasonic dispersion process was accompanied by continuous mechanical stirring to obtain amino-functionalized Ti3C2T x material dispersion, and then amino-functionalized Ti3C2T x The material dispersion was heated to 55°C and maintained for 1 hour, and then a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether was added dropwise within 30 minutes. The mixture was reacted at 55°C for 12 hours. After the reaction was completed, it was filtered with filter paper. The obtained solid product was washed three times with deionized water and then freeze-dried at -50°C for 13 hours to obtain the crown ether functionalized Mxene adsorbent.

[0049] The crown ether functionalized Mxene adsorbent prepared in this example is used to selectively recover rubidium from metallurgical wastewater. The specific steps are as follows:

[0050] The simulated metallurgical wastewater containing rubidium and cesium (prepared in the same manner as in Example 1) had a rubidium ion and cesium ion content of 100 mg / L. The pH of the wastewater was adjusted to 6.0 using hydrochloric acid. The crown ether-functionalized Mxene adsorbent was added to the wastewater to be treated at a ratio of 0.8 g per liter of wastewater to be treated. The mixture was stirred for 3 h, and the supernatant was removed by centrifugal filtration. The concentrations of rubidium and cesium ions in the supernatant were detected. The recovery rate of rubidium ions was 93%, and the recovery rate of cesium was 3.3%.

[0051] A 0.4 mol / L HCl solution was prepared as the regeneration solution, and the adsorbed crown ether functionalized MXene adsorbent was immersed in the regeneration solution for 1 hour to complete the regeneration, with a regeneration efficiency of 95%.

[0052] Example 3

[0053] (1) 3 g of LiF was slowly added to a polytetrafluoroethylene-lined reactor containing 30 mL of 7.5 M HCl solution and mechanically stirred continuously for 30 min to obtain a transparent solution. Then, 6 g of 400 mesh Ti3AlC2 was slowly added. The reaction solution was transferred to a constant temperature water bath and heated at 40 ° C for 72 h to complete the etching of Al. After the reaction was completed, the reaction solution was centrifuged at 4500 rpm for 10 min and washed with deionized water (DI) until the supernatant pH reached 6.0. The resulting solid product was vacuum dried at 60 ° C for 16 h to obtain Ti3C2T x .

[0054] (2) 1.5g Ti3C2T x The mixture was dispersed in 200 mL of anhydrous ethanol and ultrasonicated for 48 h. The mixture was placed in a refrigerator for 12 h. The supernatant was transferred to a three-necked flask and heated to 65 ° C. 15 mL of 3-aminopropyltriethoxysilane was added under magnetic stirring and kept warm for 2 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed with water and then freeze-dried at -45 ° C for 14 h to obtain amino-functionalized Ti3C2T x Material.

[0055] (3) First, 3 g of glutaraldehyde and 4.5 mL of 4-nitrobenz-15-crown-5 ether were dissolved in 120 mL of deionized water to obtain a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether for storage. Then, 1.3 g of amino-functionalized Ti3C2T x The material was dispersed into 120 mL of deionized water and ultrasonically dispersed for 30 min. The ultrasonic dispersion process was accompanied by continuous mechanical stirring to obtain amino-functionalized Ti3C2T x material dispersion, and then amino-functionalized Ti3C2T xThe material dispersion was heated to 60°C and maintained for 1 hour, and then a mixture of glutaraldehyde and 4-nitrobenz-15-crown-5 ether was added dropwise within 30 minutes. The mixture was reacted at 60°C for 14 hours. After the reaction was completed, it was filtered with filter paper. The obtained solid product was washed three times with deionized water and finally freeze-dried at -45°C for 14 hours to obtain a crown ether functionalized Mxene adsorbent sample.

[0056] The crown ether functionalized Mxene adsorbent prepared in this example is used to selectively recover rubidium from metallurgical wastewater. The specific steps are as follows:

[0057] The simulated metallurgical wastewater containing rubidium and cesium (prepared in the same manner as in Example 1) had a rubidium ion and cesium ion content of 100 mg / L. The pH of the wastewater was adjusted to 9.0 using hydrochloric acid. The crown ether-functionalized Mxene adsorbent was added to the wastewater to be treated at a ratio of 1 g per liter of the wastewater to be treated. The mixture was stirred for 4 hours, and the supernatant was removed by centrifugal filtration. The concentrations of rubidium and cesium ions in the supernatant were detected. The recovery rate of rubidium ions was 99%, and the recovery rate of cesium was 4.0%.

[0058] A 0.5 mol / L HCl solution was prepared as the regeneration solution, and the adsorbed crown ether functionalized MXene adsorbent was immersed in the regeneration solution for 2 h to complete the regeneration with a regeneration efficiency of 98%.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a crown ether functionalized Mxene adsorbent, characterized in that: The following steps are involved: Ti3C2T x The dispersion was mixed with an aminosilane reagent to undergo silanization reaction to obtain amino-functionalized Ti3C2T x Material; The crosslinker, 4-nitrobenzo-15-crown-5 ether, amino-functionalized Ti3C2T x The material and water are mixed to undergo a coupling reaction to obtain a crown ether functionalized Mxene adsorbent.

2. The preparation method according to claim 1, characterized in that The Ti3C2T x The preparation method of the dispersion comprises: x After ultrasonic dispersion in alcohol solvent, the supernatant was taken as Ti3C2T x dispersion; the Ti3C2T x The dosage ratio of the Ti3C2T x The dosage ratio of the aminosilane reagent is 1g: (8-15)mL; the ultrasonic dispersion time is 24-48h; the standing temperature is -5-10°C, and the standing time is 6-12h.

3. The preparation method according to claim 2, characterized in that The Ti3C2T x The preparation method includes: mixing LiF, hydrochloric acid solution and Ti3AlC2 to perform etching reaction to obtain Ti3C2T x ; The mass ratio of LiF and Ti3AlC2 is 1:(1~2); the concentration of the hydrochloric acid solution is 5~7.5mol / L; the usage ratio of LiF and hydrochloric acid solution is (2~3)g:(20~30)mL; the temperature of the etching reaction is 35~40℃, and the time is 48~72h.

4. The preparation method according to claim 1, characterized in that The aminosilane reagent includes one or more of 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and 3-(4-aminomethylphenyl)-aminopropyltriethoxysilane; the temperature of the silanization reaction is 55-65° C., and the time is 1-2 hours.

5. The preparation method according to claim 1, characterized in that The crosslinking agent is a dialdehyde crosslinking agent; the amount ratio of the crosslinking agent to 4-nitrobenzo-15-crown-5 ether is 1g:(1-1.5)mL; the amino-functionalized Ti3C2T x The ratio of material and 4-nitrobenzo-15-crown-5 ether is 1 g: (1-4) mL; The coupling reaction temperature is 50-60° C., and the reaction time is 10-14 h.

6. The preparation method according to claim 1, characterized in that The coupling reaction comprises: dissolving a cross-linking agent and 4-nitrobenzo-15-crown-5 ether in a portion of water to obtain a cross-linking agent-crown ether mixture; Functionalizing Ti3C2T with amino groups x The material was dispersed in the remaining water to obtain amino-functionalized Ti3C2T x Material dispersion; The amino-functionalized Ti3C2T x The material dispersion is heated to 50-60°C, and then the amino-functionalized Ti3C2T x The cross-linking agent-crown ether mixed solution is added dropwise to the material dispersion, and after the addition is completed, the mixture is reacted at 50-60° C. for 10-14 hours.

7. The crown ether functionalized Mxene adsorbent prepared by the preparation method according to any one of claims 1 to 6, characterized in that: Including amino-functionalized Ti3C2T x Materials and coupling on the amino-functionalized Ti3C2T x 4-Nitrobenzo-15-crown-5 ether on the materials.

8. Use of the crown ether functionalized Mxene adsorbent according to claim 7 in the selective adsorption of rubidium.

9. A method for separating rubidium and cesium in metallurgical wastewater, characterized in that: The following steps are involved: Metallurgical wastewater and the crown ether functionalized Mxene adsorbent according to claim 7 are mixed to perform selective adsorption of rubidium; the pH value of the metallurgical wastewater is 4-9; and the metallurgical wastewater contains rubidium ions and cesium ions.

10. The method according to claim 9, characterized in that After the selective adsorption of rubidium, the adsorbed crown ether functionalized Mxene adsorbent is regenerated; the regeneration comprises soaking the adsorbed crown ether functionalized Mxene adsorbent in a regeneration liquid; the regeneration liquid is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.1 to 0.5 mol / L, and the soaking time is 1 to 2 hours.