Ionic liquid-doped Nb2CT x Preparation method and application of MOF composite materials

Abstract

The present invention discloses an ionic liquid doped Nb2CT x Preparation method and application of MOF composite materials, Nb2AlC is prepared by using ionic liquid and hydrochloric acid as an etchant to prepare Nb2CT x The Nb2CT was prepared by in-situ synthesis. x @MOF composite material, after calcination, improves the interface and structural stability of the composite material. At the same time, it shows excellent catalytic performance in the reaction of activating periodate to degrade levofloxacin antibiotics, greatly shortening the reaction time and improving the reaction efficiency. The improved stability is conducive to enhancing the recycling rate of the composite material in the catalytic reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of Mxene@MOF composite functional materials and removal of antibiotics in water, and specifically relates to an ionic liquid-doped Nb2CT x @Preparation method and application of MOF composite materials. Background Art

[0002] Antibiotics have gradually become an emerging pollutant. They are easily enriched and persist in the environment for a long time, are not easily biodegraded, and traditional methods cannot effectively remove antibiotics from water. Therefore, there is an urgent need to develop new materials to degrade antibiotics in water.

[0003] In recent years, two-dimensional materials have been increasingly used to treat various pollutants in the environment. For example, metal organic frameworks (MOFs) are often used in advanced oxidation reactions because of their large surface area, abundant active sites, and flexible and adjustable microstructures. x The surface contains abundant functional groups such as hydroxyl groups, which are helpful for in-situ nucleation reaction with MOF materials to form composite materials. The combination of the two materials can not only overcome the shortcomings of each material, but also produce unique physical and chemical properties for degrading antibiotics in water.

[0004] MOF materials have unique porous structures and structural diversity. However, they are prone to forming nanoparticles from nanoclusters during the reaction process, which can reduce the mass transfer rate and catalytic activity. Therefore, it is necessary to stabilize MOF on a suitable matrix to make it uniformly dispersed and optimize its performance. x It has excellent electrical conductivity, rich surface functional groups and excellent mechanical flexibility, so it has a wide range of applications. x The formed composite materials are often used in electrochemical reactions. The synergistic effect between them will form electron transfer channels in the structure, which will improve the efficiency of electron transfer in the reaction. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide an ionic liquid doped Nb2CT x @MOF composite material preparation method, which uses ionic liquid as an etchant to etch Nb2AlC to prepare Nb2CT x , and then Nb2CT was prepared by in situ synthesis x @MOF composite material, which can be used to activate periodate to degrade antibiotics in water.

[0006] The present invention adopts the following technical solutions to solve the above technical problems: Nb2CT doped with ionic liquid xThe preparation method of the MOF composite material is characterized by the following specific steps:

[0007] Step S1: Ionic liquid etching of Nb2AlC to prepare Nb2CT x

[0008] 1-Ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid was added to a hydrochloric acid solution, stirred and mixed, and then Nb2AlC was added. The centrifuge tube containing the mixture was sealed and placed in an oil bath and heated to 328K for 3-5 days. The reaction system was then stirred and protected from light. After the reaction was completed, the reaction system was cooled to room temperature and washed and centrifuged several times until the pH value of the supernatant was 6-7. After collecting the substrate, a multilayer IL-Nb2CT was obtained. x , then multilayer IL-Nb2CT x Place it in water and fill it with N2 until it is saturated. Ultrasonicate it in N2 atmosphere. Then divide the ultrasonic product into centrifuge tubes and collect the dark green supernatant by centrifugation, which is the IL-Nb2CT containing a single layer or a few layers. x suspension of nanosheets;

[0009] Step S2: In-situ synthesis of Nb2CT x @MOF composite materials

[0010] Co(NO3)2·6H2O and Ni(NO3)2·6H2O were dissolved in methanol and added to the IL-Nb2CT containing a single layer or a few layers obtained in step S1 after ultrasonication at room temperature. x The suspension of nanosheets was ultrasonically mixed and then added with a methanol solution of 2-methylimidazole. The ultrasonication was continued and then magnetic stirring was performed. The obtained product was centrifuged and washed several times with methanol. The centrifuged product was collected and then placed in a vacuum drying oven at 50-60 ° C to dry. The dried sample was placed in a tube furnace and heated to 800-1000 ° C at a heating rate of 2-5 ° C / min under an inert gas atmosphere. Heat treatment was performed for 2-6 hours, and then naturally cooled to room temperature to finally obtain Nb2CT x @MOF composite materials.

[0011] The Nb2CT of the present invention x @MOF composite materials are used to activate periodate to degrade antibiotics in water.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] 1. The present invention utilizes Nb2CT etched by ionic liquid xThe strong synergistic effect between the two two-dimensional materials can form a charge transfer channel in the composite material, thereby improving the performance of activated periodate and having the characteristics of rapid electron transfer in the process of antibiotic degradation. Nb in the composite material has a strong adsorption affinity, which can adsorb metal ions to form active metal sites. At the same time, adding an appropriate amount of Nb2CT x It can increase the surface area and pore volume of the composite material, which is more conducive to improving the mass transfer rate of reactant molecules and catalytic performance, thus shortening the degradation time of antibiotics and improving the degradation efficiency of antibiotics.

[0014] 2. Nb2CT doped with ionic liquid x @MOF composite materials, ionic liquids can be coated on Nb2CT as etchants x surface, which not only improves the Nb2CT x The antioxidant capacity of Nb2CT x It provides a good medium for bonding with other two-dimensional materials. The functional groups of the organic bridge in MOF can bond with Nb2CT x The surface end groups are bonded, which greatly enhances the interface stability and structural stability of the composite material, thereby ensuring the recyclability of the material in the degradation reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Nb2CT is obtained by etching Nb2AlC in Example 1 with ionic liquid + hydrochloric acid solution. x SEM images of .

[0016] Figure 2 Nb2CT prepared in Example 1 x @SEM image of MOF composite material.

[0017] Figure 3 Nb2CT x , MOF and Nb2CT x @The concentration of levofloxacin degraded by MOF composite material changes over time.

[0018] Figure 4 Ti3C2T x @MOF、Mo2CT x @MOF and Nb2CT x @The concentration of levofloxacin degraded by MOF composite material changes over time. DETAILED DESCRIPTION

[0019] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention.

[0020] Example 1

[0021] Preparation of Nb2CT by Ionic Liquid Etching of Nb2AlC x

[0022] First, prepare 20mL of 9M hydrochloric acid solution in a 50mL centrifuge tube, weigh 1.314g of 1-ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid ([Emim]PF6), slowly pour it into the hydrochloric acid solution, stir for 10 minutes, weigh 1g of Nb2AlC and slowly add it to the previous mixed solution. Subsequently, seal the centrifuge tube and place it in an oil bath. After heating to 328K, react for 3d. The system is slowly stirred and protected from light. After the reaction is completed, the system is cooled to room temperature, centrifuged at 3000rpm for 15min, and the supernatant is poured out. Add 30mL of secondary water to the centrifuge tube, continue centrifugation, and pour out the supernatant. Repeat this operation until the pH value of the supernatant is about 6. After collecting the substrate, multilayer IL-Nb2CT is obtained. x Then, multilayer IL-Nb2CT x Place in a 250 mL round-bottom flask, add about 200 mL of secondary water, fill with N2 to saturation, and ultrasonicate in N2 atmosphere for 3 hours. Then, divide the ultrasonicated product into centrifuge tubes and centrifuge at 3000 rpm for 40 minutes. The collected dark green supernatant is the IL-Nb2CT containing a single layer or a few layers. x Suspension of nanosheets.

[0023] In-situ synthesis of Nb2CT x @MOF composite materials

[0024] Co(NO3)2·6H2O and Ni(NO3)2·6H2O were dissolved in methanol and added to 20 mL of the previously prepared IL-Nb2CT containing single or few layers after ultrasonication at room temperature for 10 min. x The mixture was ultrasonicated for 20 min, 2-methylimidazole was dissolved in methanol solution, and the Nb2CT xThe suspension was mixed with a methanol solution containing 2-methylimidazole, ultrasonicated for 30 minutes, and then magnetically stirred at room temperature for 8 hours. The obtained product was centrifugally washed with methanol four times, collected by centrifugation, and then dried in a vacuum drying oven at 60°C. The dried sample was placed in a tubular furnace, vacuumed and passed through N2 three times to expel the air inside the tube, and then heated to 900°C at a heating rate of 3°C / min and maintained at 900°C for 5 hours, and then naturally cooled to room temperature. All heating and cooling steps were carried out in a N2 atmosphere. The obtained calcined product was directly used in the subsequent reaction.

[0025] Example 2

[0026] Preparation of Nb2CT by Ionic Liquid Etching of Nb2AlC x

[0027] First, prepare 20mL of 9M hydrochloric acid solution in a 50mL centrifuge tube, weigh 1.314g of 1-ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid ([Emim]PF6), slowly pour it into the hydrochloric acid solution, stir for 10 minutes, weigh 1g of Nb2AlC and slowly add it to the previous mixed solution. Subsequently, seal the centrifuge tube and place it in an oil bath. After heating to 328K, react for 3d. The system is slowly stirred and protected from light. After the reaction is completed, the system is cooled to room temperature, centrifuged at 3000rpm for 5min, and the supernatant is poured out. Then 30mL of secondary water is added to the centrifuge tube, and the supernatant is poured out after continuing centrifugation. Repeat this operation until the pH value of the supernatant is about 6. After collecting the substrate, multilayer IL-Nb2CT is obtained. x Then, multilayer IL-Nb2CT x Place in a 250 mL round-bottom flask, add about 200 mL of secondary water, fill with N2 to saturation, and ultrasonicate in N2 atmosphere for 3 hours. Then, divide the ultrasonicated product into centrifuge tubes and centrifuge at 3000 rpm for 40 minutes. The collected dark green supernatant is the IL-Nb2CT containing a single layer or a few layers. x Suspension of nanosheets.

[0028] In-situ synthesis of Nb2CT x @MOF composite materials

[0029] Co(NO3)2·6H2O and Ni(NO3)2·6H2O were dissolved in methanol and added to 20 mL of the previously prepared IL-Nb2CT containing single or few layers after ultrasonication at room temperature for 10 min. x The mixture was ultrasonicated for 20 min, 2-methylimidazole was dissolved in methanol solution, and Nb2CT xThe suspension was mixed with a methanol solution containing 2-methylimidazole, ultrasonicated for 30 minutes, and then magnetically stirred at room temperature for 8 hours. The obtained product was centrifugally washed with methanol four times, collected by centrifugation, and then dried in a vacuum drying oven at 60°C. The dried sample was placed in a tubular furnace, vacuumed and passed through N2 three times to expel the air inside the tube, and then heated to 800°C at a heating rate of 3°C / min and maintained at 800°C for 5 hours, and then naturally cooled to room temperature. All heating and cooling steps were carried out in a N2 atmosphere. The obtained calcined product was directly used in the subsequent reaction.

[0030] Example 3

[0031] Preparation of Nb2CT by Ionic Liquid Etching of Nb2AlC x

[0032] First, prepare 20mL of 9M hydrochloric acid solution in a 50mL centrifuge tube, weigh 1.314g of 1-ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid ([Emim]PF6), slowly pour it into the hydrochloric acid solution, stir for 10 minutes, weigh 1g of Nb2AlC and slowly add it to the previous mixed solution. Subsequently, seal the centrifuge tube and place it in an oil bath. After heating to 328K, react for 5 days. The system is slowly stirred and protected from light. After the reaction is completed, the system is cooled to room temperature, centrifuged at 3000rpm for 10 minutes, and the supernatant is poured out. Then 30mL of secondary water is added to the centrifuge tube, and the supernatant is poured out after continuing centrifugation. Repeat this operation until the pH value of the supernatant is about 6. After collecting the substrate, multilayer IL-Nb2CT is obtained. x Then, multilayer IL-Nb2CT x Place in a 250 mL round-bottom flask, add about 200 mL of secondary water, fill with N2 to saturation, and ultrasonicate in N2 atmosphere for 3 hours. Then, divide the ultrasonicated product into centrifuge tubes and centrifuge at 3000 rpm for 40 minutes. The collected dark green supernatant is the IL-Nb2CT containing a single layer or a few layers. x Suspension of nanosheets.

[0033] In-situ synthesis of Nb2CT x @MOF composite materials

[0034] Co(NO3)2·6H2O and Ni(NO3)2·6H2O were dissolved in methanol and added to 20 mL of the previously prepared IL-Nb2CT containing single or few layers after ultrasonication at room temperature for 10 min. x The mixture was ultrasonicated for 20 min, 2-methylimidazole was dissolved in methanol solution, and Nb2CT xThe suspension was mixed with a methanol solution containing 2-methylimidazole, ultrasonicated for 30 minutes, and then magnetically stirred at room temperature for 8 hours. The obtained product was centrifugally washed with methanol four times, collected by centrifugation, and then dried in a vacuum drying oven at 60°C. The dried sample was placed in a tubular furnace, vacuumed and passed through N2 three times to expel the air inside the tube, and then heated to 900°C at a heating rate of 3°C / min and maintained at 800°C for 5 hours, and then naturally cooled to room temperature. All heating and cooling steps were carried out in a N2 atmosphere. The obtained calcined product was directly used in the subsequent reaction.

[0035] Comparative Example 1

[0036] Preparation of Ti3C2T by Ionic Liquid Etching of Ti3AlC2 x

[0037] First, prepare 20mL of 9M HCl solution (15mL of 12M concentrated hydrochloric acid + 5mL of ultrapure water) in a 50mL centrifuge tube, then weigh 1.314g of 1-ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid ([Emim]PF6) and slowly pour it into the hydrochloric acid solution for magnetic stirring. After 10 minutes, slowly add 1g of Ti3AlC2 powder to the mixed suspension. Subsequently, seal the centrifuge tube and place it in an oil bath, heat it to 328K and react for 30 hours, during which the system is slowly stirred. After the reaction is completed, cool the system to room temperature, centrifuge it at 3000rpm for 5 minutes, and pour the supernatant. Then add 30mL of secondary water to the centrifuge tube, continue centrifugation and pour the supernatant. Repeat this process until the pH value of the supernatant is about 6. After collecting the substrate, multilayer IL-Ti3C2T x Then the multilayer IL-Ti3C2T x Place in a 250mL round-bottom flask, add about 200mL of secondary water, fill with N2 to saturation, and ultrasonicate for 1h under N2 atmosphere. Then, divide the ultrasonicated product into centrifuge tubes and centrifuge at 3000rpm for 30min to collect Ti3C2T x Suspension.

[0038] Comparative Example 2

[0039] Preparation of Mo2CT by Ionic Liquid Etching of Mo2Ga2C x

[0040] First, prepare 20mL of 9M HCl solution (15mL of 12M concentrated hydrochloric acid + 5mL of ultrapure water) in a 50mL centrifuge tube, then weigh 1.576g of 1-ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid ([Emim]PF6) and slowly pour it into the hydrochloric acid solution for magnetic stirring. After 10 minutes, slowly add the weighed 1g of Mo2Ga2C powder to the mixed suspension. Subsequently, the centrifuge tube is sealed and placed in an oil bath, heated to 333K and reacted for 6 days, during which the system is slowly stirred. After the reaction is completed, the system is cooled to room temperature, centrifuged at 3000rpm for 5 minutes, and the supernatant is poured out. Then 30mL of secondary water is added to the centrifuge tube, and the supernatant is poured out after continuing centrifugation. Repeat this process until the pH value of the supernatant is about 6. After collecting the substrate, multilayer IL-Mo2CT is obtained. x Then the multi-layer IL-Mo2CT x Place in a 250mL round-bottom flask, add about 200mL of secondary water, fill with N2 to saturation, and ultrasonicate for 1 hour under N2 atmosphere. Then, divide the ultrasonicated product into centrifuge tubes and centrifuge at 3000rpm for 30min to collect Mo2CT x Suspension.

[0041] Composite materials prepared in Example 1 and Comparative Examples 1-2 activated periodate to degrade antibiotics in water

[0042] In a 50mL beaker, 0.4g / L of different ionic liquid-doped composite materials, 100mM / L NaIO4, and 200mg / L of antibiotic were prepared. The catalyst was dispersed in 100mL of the antibiotic solution. N2 was then saturated, followed by ultrasonic dispersion in an ice-water bath for 15 minutes to establish adsorption-desorption equilibrium on the catalyst surface. 1000µL of NaIO4 solution was added to the reaction system to stimulate the reaction. At regular reaction time intervals (0, 2min, 6min, 8min, 10min, 15min, 20min, and 30min), 5mL samples were removed, filtered, and analyzed for antibiotic concentration using high-performance liquid chromatography.

[0043] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. Ionic liquid-doped Nb2CT x The preparation method of MOF composite material is characterized in that The specific steps are: Step S1: Ionic liquid etching of Nb2AlC to prepare Nb2CT x 1-Ethyl-3-methylimidazolium hexafluorophosphorus ionic liquid was added to a hydrochloric acid solution, stirred and mixed, and then Nb2AlC was added. The centrifuge tube containing the mixture was sealed and placed in an oil bath and heated to 328K for 3-5 days. The reaction system was then stirred and protected from light. After the reaction was completed, the reaction system was cooled to room temperature and washed and centrifuged several times until the pH value of the supernatant was 6-7. After collecting the substrate, a multilayer IL-Nb2CT was obtained. x , then multilayer IL-Nb2CT x Place it in water and fill it with N2 until it is saturated. Ultrasonicate it in N2 atmosphere. Then divide the ultrasonic product into centrifuge tubes and collect the dark green supernatant by centrifugation, which is the IL-Nb2CT containing a single layer or a few layers. x suspension of nanosheets; Step S2: In-situ synthesis of Nb2CT x @MOF composite materials Dissolve Co(NO3)2·6H2O and Ni(NO3)2·6H2O in methanol and add them to the IL-Nb2CT containing a single layer or a few layers obtained in step S1 after ultrasonication at room temperature. x The suspension of nanosheets was ultrasonically mixed and then added with a methanol solution of 2-methylimidazole. The ultrasonication was continued and then magnetic stirring was performed. The obtained product was centrifuged and washed several times with methanol. The centrifuged product was collected and then placed in a vacuum drying oven at 50-60 ° C to dry. The dried sample was placed in a tube furnace and heated to 800-1000 ° C at a heating rate of 2-5 ° C / min under an inert gas atmosphere. Heat treatment was performed for 2-6 hours, and then naturally cooled to room temperature to finally obtain Nb2CT x @MOF composite materials.

2. Ionic liquid-doped Nb2CT prepared according to the method of claim 1 x @MOF composite materials are used to activate periodate to degrade antibiotics in water.

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