Preparation method of layered confined space v2c and application thereof

Abstract

This invention discloses a method for preparing V2C with layered confined spaces and its applications, belonging to the field of water treatment technology. The invention provides a method for preparing V2C MXenes materials by high-temperature in-situ etching of the V2AlC MAX phase using hydrofluoric acid. Due to its thin and loose layered structure, more active sites are exposed. The layered structure forms nano-confined spaces, which can better activate persulfate or peracetic acid, resulting in good removal effects on emerging pollutants in water. In this invention, the V2C / PMS system exhibits a rapid degradation rate for BPA, achieving 100% complete degradation within 7.5 minutes. The V2C / PAA system also exhibits a rapid degradation rate for BPA, achieving 90% degradation within 40 minutes.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for preparing V2C with layered confined space and its application. Background Technology

[0002] Confined catalysis, by regulating the structure, morphology, and electronic state of catalysts, can effectively control the adsorption, diffusion, and reaction processes of reactant molecules on the catalyst surface, thereby enhancing catalytic efficiency and reactivity. It is currently a hot topic in catalytic reaction research.

[0003] Currently, biological methods, adsorption methods, and membrane filtration are the mainstream strategies for treating emerging pollutants (ECs) in urban wastewater treatment plants. However, these methods suffer from high energy consumption and cost, as well as poor EC removal efficiency, severely limiting their application in real-world environments. Therefore, developing a highly efficient and clean EC removal technology that can be widely applied in practical environments is a current research hotspot and focus.

[0004] Advanced oxidation processes (AOPs) are an important method for removing emerging pollutants from water. Currently, the most researched AOPs include activated hydrogen peroxide (H2O2), electrochemical oxidation, and catalytic ozone oxidation. Persulfate advanced oxidation (SR-AOP) and peracetic acid advanced oxidation (PAA-AOP) are emerging AOP technologies for treating recalcitrant pollutants in water. Compared with traditional AOPs based on the formation and oxidation of hydroxyl radicals (·OH), they have a wider pH range of applicability, stronger oxidizing power under neutral conditions, and a longer free radical half-life, attracting widespread attention from researchers.

[0005] As emerging two-dimensional materials, transition metal carbides, nitrides, and carbonitrides (MXenes) possess broad transition metal planes, hydrophilic terminal functional groups (-O, -OH, or -F), and easily tunable surface / interface structures, leading to their widespread application in environmental remediation, energy storage, and biomedicine. Furthermore, the hierarchical structure of MXenes facilitates the formation of nanoscale confined spaces, significantly reducing reaction energy barriers in catalytic processes and enhancing catalytic activity.

[0006] Currently, in PMS-based advanced oxidation processes, most researchers focus on Ti3C2T x The research, however, on Ti3C2T x It is characterized by low catalytic activity, poor cycle stability, and easy deactivation of low-valent titanium sites, resulting in low pollutant removal efficiency and poor cycle stability. Compared to Ti3C2T... xNovel V2Cs exhibit superior catalytic activity and cycle stability. However, most current research focuses on the development and design of bulk V2Cs, which greatly limits the activity of the limited multi-oxide-state vanadium sites, making it unable to efficiently activate persulfate and peracetic acid. Summary of the Invention

[0007] To address the aforementioned issues, this invention employs a high-temperature wet chemical method. By efficiently removing the Al layer from V2AlC in a localized high-temperature environment, it achieves effective layered stratification of V2C. The accordion-like structure provides ample reaction sites for persulfate and peracetic acid and naturally constructs a "confined catalytic space," enabling V2C to remove recalcitrant organic pollutants from water bodies with high stoichiometric efficiency by activating persulfate and peracetic acid.

[0008] A method for preparing V2C with layered confined space is specifically carried out according to the following steps:

[0009] 1. Mix V2AlC and hydrofluoric acid solution evenly, then put it into a polytetrafluoroethylene bottle and stir it in a constant temperature water bath for a certain period of time to obtain a mixed solution.

[0010] 2. Pour the mixed solution into a centrifuge tube, centrifuge it in a centrifuge, and wash the mixed solution repeatedly with deionized water until the supernatant after centrifugation is neutral;

[0011] 3. Collect the precipitate after centrifugation, place it in a vacuum drying oven for vacuum drying, and collect it in a sealed bag to obtain V2C with layered confined space.

[0012] A layered confined space V2C is used to activate persulfate to degrade bisphenol A; the persulfate is potassium persulfate or sodium persulfate.

[0013] A layered confined space V2C is used to activate peracetic acid to degrade bisphenol A; the peracetic acid has a mass fraction of 35%.

[0014] Advantages of this invention:

[0015] I. This invention provides a method for preparing V2C MXenes materials by high-temperature in-situ etching of V2AlC MAX phase with hydrofluoric acid. Due to its thin and loose layered structure, more active sites are exposed. The layered structure forms a nano-confined space, which can better activate persulfate or peracetic acid and has a good removal effect on emerging pollutants in water.

[0016] Second, the V2C / PMS system in this invention has a fast degradation rate of BPA, and can achieve 100% complete degradation of BPA within 7.5 minutes.

[0017] Third, the V2C / PAA system in this invention has a fast degradation rate of BPA, and can achieve 90% degradation of BPA within 40 minutes. Attached Figure Description

[0018] Figure 1 The images are SEM images, where (a) and (b) are V2AlC, and (c) and (d) are V2C with layered confined space prepared in Example 1.

[0019] Figure 2 XRD patterns of V2AlC and V2C with layered confined space prepared in Example 1;

[0020] Figure 3 Degradation performance and rate constant of BPA by V2AlC and V2C activated PMS with layered confined space prepared in Example 1;

[0021] Figure 4 Degradation performance and rate constant of BPA by V2AlC and V2C activated with layered confined space prepared in Example 1. Detailed Implementation

[0022] Specific Implementation Method 1: This implementation method describes a method for preparing V2C with layered confined space, which is specifically completed according to the following steps:

[0023] 1. Mix V2AlC and hydrofluoric acid solution evenly, then put it into a polytetrafluoroethylene bottle and stir it in a constant temperature water bath for a certain period of time to obtain a mixed solution.

[0024] 2. Pour the mixed solution into a centrifuge tube, centrifuge it in a centrifuge, and wash the mixed solution repeatedly with deionized water until the supernatant after centrifugation is neutral;

[0025] 3. Collect the precipitate after centrifugation, place it in a vacuum drying oven for vacuum drying, and collect it in a sealed bag to obtain V2C with layered confined space.

[0026] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass fraction of the hydrofluoric acid solution mentioned in step one is 30%~70%. The other steps are the same as in Specific Implementation Method One.

[0027] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the mass ratio of V2AlC to the volume ratio of hydrofluoric acid solution in step one is 2.0 g:(50 mL~150 mL). The other steps are the same as in Specific Implementation Method One or Two.

[0028] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the water bath stirring temperature in step one is 35℃~100℃, and the water bath stirring time is 72h~168h. Other steps are the same as in Specific Implementation Methods One to Three.

[0029] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the centrifugation speed in step two is 6000 rpm to 8000 rpm, and the centrifugation time is 3 min / cycle to 10 min / cycle. The other steps are the same as in Specific Implementation Methods One to Four.

[0030] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the vacuum drying temperature in step three is 60℃~80℃, and the vacuum drying time is 24h~48h. The other steps are the same as in Specific Implementation Methods One to Five.

[0031] Specific Implementation Method Seven: This implementation method uses a layered confined space V2C to activate persulfate to degrade bisphenol A; the persulfate is potassium peroxymonosulfate or sodium persulfate.

[0032] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that it has a layered confined space V2C for activating persulfate degradation of bisphenol A, specifically accomplished according to the following steps:

[0033] V2C with layered confined space was added to a neutral aqueous solution containing bisphenol A and stirred for 3 to 5 minutes. Then persulfate was added and stirred for 0.5 to 8 minutes to obtain an aqueous sample of bisphenol A degraded.

[0034] The mass ratio of the layered confined space V2C to the volume ratio of the aqueous solution containing bisphenol A is 5 mg: 100 mL.

[0035] The mass ratio of the persulfate to the volume ratio of the aqueous solution containing bisphenol A is 5 mg: 100 mL.

[0036] The concentration of bisphenol A in the aqueous solution containing bisphenol A is 10 mg / L to 20 mg / L. Other steps are the same as in embodiments one through seven.

[0037] Specific Implementation Method Nine: This implementation method uses a layered confined space V2C to activate peracetic acid to degrade bisphenol A; the mass fraction of the peracetic acid is 35%.

[0038] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that it has a layered confined space V2C for activating the hydrolysis of bisphenol A by peracetic acid, specifically accomplished according to the following steps:

[0039] V2C with layered confined space was added to a neutral aqueous solution containing bisphenol A and stirred for 3 to 5 minutes. Then peracetic acid was added and stirred for 5 to 40 minutes to obtain water after bisphenol A degradation.

[0040] The mass ratio of the layered confined space V2C to the volume ratio of the aqueous solution containing bisphenol A is 10 mg: 100 mL.

[0041] The volume ratio of the peracetic acid to the aqueous solution containing bisphenol A is 0.05 mL: 100 mL.

[0042] The concentration of bisphenol A in the aqueous solution containing bisphenol A is 10 mg / L to 20 mg / L. Other steps are the same as in embodiments one through nine.

[0043] The beneficial effects of the present invention are verified using the following embodiments:

[0044] The instruments used in the following embodiments and test examples are: scanning electron microscope (manufacturer: Zeiss, Germany, model: Zeiss Gemini 300); fully automated X-ray diffractometer (manufacturer: Bruker, Germany, model: Bruker D8 Advance); high performance liquid chromatograph (manufacturer: Shimadzu, Japan, model: Shimadzu LC-16).

[0045] Example 1: A method for preparing V2C with layered confined space, specifically completed according to the following steps:

[0046] 1. Mix 2.0g V2AlC and 100mL hydrofluoric acid solution evenly, then put the mixture into a polytetrafluoroethylene bottle and stir continuously for 96 hours in a constant temperature water bath at 35℃ to obtain a mixed solution.

[0047] The hydrofluoric acid solution mentioned in step one has a mass fraction of 40%.

[0048] 2. Pour the mixed solution into a centrifuge tube, centrifuge it in a centrifuge, and wash the mixed solution repeatedly with deionized water until the supernatant after centrifugation is neutral;

[0049] The centrifugation speed in step two is 6000 rpm, and the centrifugation time is 5 min / cycle;

[0050] 3. Collect the precipitate after centrifugation, place it in a vacuum drying oven for vacuum drying, and collect it in a sealed bag to obtain V2C with layered confined space;

[0051] The vacuum drying temperature in step three is 60°C, and the vacuum drying time is 24 hours.

[0052] Figure 1 The images are SEM images, where (a) and (b) are V2AlC, and (c) and (d) are V2C with layered confined space prepared in Example 1.

[0053] from Figure 1 As can be seen, Example 1 prepared V2C with layered confined spaces using hydrofluoric acid etching. Compared to the bulk structure of V2AlC MAX phase, the V2CMXenes material after hydrofluoric acid etching exhibits a honeycomb layered morphology on the surface, with a thin and loose structure that exposes more active sites. The layered structure forms nano-confined spaces, which enhances the catalytic reaction process.

[0054] Figure 2 XRD patterns of V2AlC and V2C with layered confined space prepared in Example 1;

[0055] from Figure 2 It can be seen that the diffraction peaks at 2θ=13.6° and 41.3° correspond to the characteristic diffraction peaks of V2AlC. Compared with V2AlC, the characteristic peak intensity of V2C is reduced, and a new (002) diffraction peak appears at 2θ=7.7°, indicating that V2C MXenes layered materials with confined space were successfully prepared by in-situ hydrofluoric acid etching.

[0056] Application Experiment 1:

[0057] The degradation of bisphenol A using potassium persulfate with layered confined space V2C activated by the material prepared in Example 1 was carried out according to the following steps:

[0058] The catalytic reaction system was carried out in a 100 mL beaker at a constant temperature of 25°C in a constant temperature magnetically stirred water bath. With the initial pH of the solution neutral, 100 mL of BPA aqueous solution (10 mg / L) was added to each beaker. After stirring at a constant temperature for 3 min to ensure uniformity of the pollutant and the system, 5 mg of V2C prepared in Example 1 and 5 mg of V2AlC were added to each beaker, and stirring was continued for 3 min. Then, 5 mg of PMS (potassium peroxymonosulfate) was added to each beaker to conduct the BPA (bisphenol A) degradation experiment. Samples were taken using a 1 mL syringe at 30 s, 60 s, 120 s, 210 s, 330 s, and 450 s after the addition of PMS. After filtration through a 0.22 μm nylon 66 filter, the samples were mixed with excess sodium thiosulfate to terminate the reaction. Finally, high-performance liquid chromatography (HPLC) analysis was performed.

[0059] As a control, V2C and V2AlC were omitted. The experimental results are as follows: Figure 3 As shown.

[0060] Figure 3Degradation performance and rate constant of BPA by V2AlC and V2C activated PMS with layered confined space prepared in Example 1;

[0061] from Figure 3 It can be seen that without a catalyst, PMS removes approximately 5% of BPA, exhibiting almost no degradation performance. When only V2C catalyst is added without PMS, the system shows almost no adsorption or degradation of BPA, with a removal rate of only about 5%, indicating that neither the catalyst nor PMS itself degrades BPA. Adding both PMS and unmodified MAX phase material V2AlC has almost no degradation effect on BPA. However, when PMS and V2C coexist, the V2C / PMS system shows a faster degradation rate of BPA in the first 4 minutes, achieving 100% complete degradation within 7.5 minutes. This demonstrates that V2C has an activating effect on PMS; the layered structure of V2C forms a nano-confined space, which is beneficial for catalytic activation of PMS to generate highly oxidizing active species, promoting the catalytic degradation of BPA. Figure 3 As shown in (b), the kinetic constant of the V2C+PMS system is about 100 times that of other systems, indicating that V2C has good PMS catalytic activity.

[0062] Application Experiment 2:

[0063] The degradation of bisphenol A by peracetic acid using V2C activated peracetic acid with layered confined space, prepared in Example 1, was carried out according to the following steps:

[0064] The catalytic reaction system was carried out in a 100 mL beaker at a constant temperature of 25℃ in a constant temperature magnetically stirred water bath. Under the condition that the initial pH of the solution was neutral, 100 mL of BPA aqueous solution (10 mg / L) was added to each beaker. After stirring at a constant temperature for 3 min to ensure that the pollutants were homogeneous with the system, 10 mg of V2C and 10 mg of V2AlC were added to each beaker respectively. Stirring was continued for about 3 min. Then, 0.05 mL of 35% PAA (peracetic acid) was added to each beaker to carry out the BPA (bisphenol A) degradation experiment. Samples were taken using a 1 mL syringe at 2 min, 5 min, 10 min, 15 min, 25 min and 40 min after the addition of PAA. The samples were filtered through a 0.22 μm nylon 66 filter and mixed with excess sodium thiosulfate to terminate the reaction. Finally, high performance liquid chromatography analysis was performed.

[0065] As a control, V2C and V2AlC were omitted. The experimental results are as follows: Figure 4 As shown.

[0066] from Figure 4It can be seen that without a catalyst, PAA removes approximately 10% of BPA, exhibiting almost no degradation performance. When only V2C catalyst is added without PAA, the system shows almost no adsorption or degradation of BPA, with a removal rate of only about 6%, indicating poor degradation effects of both the catalyst and PAA alone. Adding both PAA and unmodified MAX phase material V2AlC has almost no degradation effect on BPA. However, when PAA and V2C coexist, the V2C / PAA system shows a faster degradation rate of BPA within the first 25 minutes, achieving 90% degradation within 40 minutes. This demonstrates that V2C has an activating effect on PAA; the layered structure of V2C forms a nano-confined space, which is beneficial for providing more active sites for PAA activation, generating highly oxidizing active species, and promoting the catalytic degradation of BPA. Figure 4 As shown in (b), the kinetic constant of the V2C+PAA system is about 1000 times that of other systems.

Claims

1. An application with layered confined space V2C, characterized in that, A layered confined space V2C is used to activate persulfate to degrade bisphenol A, achieving a degradation rate of 100%. The persulfate is potassium peroxymonosulfate or sodium persulfate. The activation of the persulfate by the layered confined space V2C for bisphenol A degradation is specifically accomplished through the following steps: V2C with layered confined space was added to a neutral aqueous solution containing bisphenol A and stirred for 3 to 5 minutes. Then persulfate was added and stirred for 0.5 to 8 minutes to obtain an aqueous sample of bisphenol A degraded. The mass ratio of the layered confined space V2C to the volume ratio of the aqueous solution containing bisphenol A is 5 mg: 100 mL. The mass ratio of the persulfate to the volume ratio of the aqueous solution containing bisphenol A is 5 mg: 100 mL. The concentration of bisphenol A in the aqueous solution containing bisphenol A is 10 mg / L to 20 mg / L; The V2C surface with layered confined space exhibits a honeycomb layered morphology and has a thin and loose structure. The preparation method is specifically carried out according to the following steps:

1. Mix 2.0g V2AlC and 100mL hydrofluoric acid solution evenly, then put the mixture into a polytetrafluoroethylene bottle and stir continuously for 96 hours in a constant temperature water bath at 35℃ to obtain a mixed solution. The hydrofluoric acid solution mentioned in step one has a mass fraction of 40%.

2. Pour the mixed solution into a centrifuge tube, centrifuge it in a centrifuge, and wash the mixed solution repeatedly with deionized water until the supernatant after centrifugation is neutral; The centrifugation speed in step two is 6000 rpm, and the centrifugation time is 5 min / cycle; 3. Collect the precipitate after centrifugation, place it in a vacuum drying oven for vacuum drying, and collect it in a sealed bag to obtain V2C with layered confined space; The vacuum drying temperature in step three is 60°C, and the vacuum drying time is 24 hours.

2. An application with layered confined space V2C, characterized in that, A layered confined space V2C is used to activate peracetic acid to degrade bisphenol A; the peracetic acid has a mass fraction of 35%; the activation of peracetic acid to degrade bisphenol A using a layered confined space V2C is specifically carried out according to the following steps: V2C with layered confined space was added to a neutral aqueous solution containing bisphenol A and stirred for 3 to 5 minutes. Then peracetic acid was added and stirred for 5 to 40 minutes to obtain water after bisphenol A degradation. The mass ratio of the layered confined space V2C to the volume ratio of the aqueous solution containing bisphenol A is 10 mg: 100 mL. The volume ratio of the peracetic acid to the aqueous solution containing bisphenol A is 0.05 mL: 100 mL. The concentration of bisphenol A in the aqueous solution containing bisphenol A is 10 mg / L to 20 mg / L; The V2C surface with layered confined space exhibits a honeycomb layered morphology and has a thin and loose structure. The preparation method is specifically carried out according to the following steps:

1. Mix 2.0g V2AlC and 100mL hydrofluoric acid solution evenly, then put the mixture into a polytetrafluoroethylene bottle and stir continuously for 96 hours in a constant temperature water bath at 35℃ to obtain a mixed solution. The hydrofluoric acid solution mentioned in step one has a mass fraction of 40%.

2. Pour the mixed solution into a centrifuge tube, centrifuge it in a centrifuge, and wash the mixed solution repeatedly with deionized water until the supernatant after centrifugation is neutral; The centrifugation speed in step two is 6000 rpm, and the centrifugation time is 5 min / cycle; 3. Collect the precipitate after centrifugation, place it in a vacuum drying oven for vacuum drying, and collect it in a sealed bag to obtain V2C with layered confined space; The vacuum drying temperature in step three is 60°C, and the vacuum drying time is 24 hours.

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