Preparation and application of a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water

Abstract

The present invention belongs to the technical field of organic pollutant degradation, and discloses the preparation and application of a confined Fenton-like catalytic material for high-efficiency mineralization and removal of perfluorinated compounds in water. The preparation process of the confined single-atom Co-MXenes material is simple, and the amount of ClCo2-6H2O can be adjusted to achieve the loading amount of single-atom Co. At the same time, the confined single-atom material can retain free radicals when activating persulfate, so that it can react with perfluorinated compounds for defluorination, making the oxidation of perfluorinated compounds more efficient. In addition, the nano-confined space of MXenes can shield the interference of organic macromolecules in the water environment, and still maintain an efficient mineralization ability for perfluorinated compounds in complex wastewater. The above process does not require external energy, and realizes reduction defluorination and oxidation removal in one system, which has profound reference significance for the treatment of wastewater containing perfluorinated pollutants.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic pollutant degradation, and more specifically, relates to the preparation and application of a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water. Co single atoms are anchored in the confined environment of the nanolayer of MXenes to activate persulfate to produce and Free radicals are used for the defluorination and degradation of perfluorinated pollutants in water. Background Art

[0002] Perfluorinated compounds are widely used in various consumer products and industrial production due to their oil-proof, water-proof, high-temperature resistance and extremely high chemical stability. However, they are highly toxic, persistent and bioaccumulative, and enter the environment in large quantities through industrial wastewater discharge, causing lasting damage to humans and the ecological environment. Currently, due to the lack of standards to limit the emission of perfluorinated compound pollutants, most industrial wastewater treatment plans do not have facilities designed to eliminate perfluorinated compounds. Therefore, after industrial wastewater treatment plants, only a small part of perfluorinated compounds (up to 15%) can be removed (mainly through physical and biological adsorption), and the removed part is quickly released back into the wastewater treatment plant or the environment, followed by treatment steps such as media filter backwashing and sludge application. At the same time, an increasing number of perfluorinated intermediates have been found in wastewater treatment plant discharges after conventional treatment processes, making it difficult to achieve complete removal of perfluorinated compounds. Therefore, the ideal treatment method is to develop chemical treatment technology to deeply remove perfluorinated pollutants and achieve decomposition and mineralization.

[0003] Due to the strength of the C-F bond, perfluorinated compounds are difficult to destroy by most oxidants used in water treatment. Although advanced oxidation technology (AOP) can decompose some perfluorinated compounds, the direct oxidation process is energy-intensive and inefficient. Zhang et al. revealed in "Oxidation of Per-and Polyfluoroalkyl Ether Acids and Other Per-and Polyfluoroalkyl Substances by Sulfate and Hydroxyl Radicals: Kinetic Insights from Experiments and Models" that the second-order rate constant of most perfluorinated compounds with free radicals does not exceed 10 5 M -1 s -1. At present, the pretreatment mode of "reduction defluorination" of perfluorinated pollutants can accelerate and improve the subsequent AOP treatment effect, and the development of corresponding treatment technology has become a hot research direction in recent years. For example, Liu et al. used the thermal activation of persulfate combined with UV-sulfite reduction in "Near-Quantitative Defluorination of Perfluorinated and Fluorotelomer Carboxylates and Sulfonates with Integrated Oxidation and Reduction" to achieve the defluorination and degradation of most perfluorinated compounds. Nevertheless, since the currently reported treatment methods rely on the catalytic reaction process of external light, heat or electrical energy, they have strict requirements on the structure of the reactor, water quality conditions, operating parameters and other aspects, the operating cost is high, and the maintenance is difficult, and the conditions for large-scale application are not yet met.

[0004] Fenton-like water treatment technology is currently the preferred technology for dealing with high-load and difficult-to-degrade organic pollutants in industrial wastewater treatment. Among them, the persulfate-based Fenton-like process has many advantages over traditional Fenton technology, such as high reaction intensity, applicability to neutral pH, and easy storage / transportation / dosing of reagents, and is therefore of great development and application value. Compared with traditional oxidation systems, catalytic reactions occurring under spatial confinement can change the physicochemical properties of free radicals (including the coordinated water environment, the ability to gain or lose electrons, mass transfer efficiency, etc.), thereby affecting the kinetics and thermodynamic properties of the reaction; in the article "Subnanoscale spatially confined heterogeneous Fenton reaction enables mineralization of perfluorooctanoic acid", Zhang et al. designed a FeOCl confined reaction layer that can enhance the reduction function of superoxide radicals and be used for dehalogenation.

[0005] Therefore, the present invention utilizes the special effect of nano-confinement to regulate the reduction and defluorination function. Free radicals and those with oxidative decomposition function The two work together to achieve the special effect of mineralizing and treating various perfluorinated compound pollutants in industrial wastewater. Summary of the Invention

[0006] In view of the above problems, the purpose of the present invention is to provide a preparation and application of a confined Fenton-like catalytic material for the high-efficiency mineralization removal of perfluorinated compounds in water. The prepared Co-MXenes and alumina ceramic ball composite catalyst can be loaded into the Fenton-like bed reaction layer, and the confined environment is constructed by the MXenes interlayer spacing to activate the production of persulfate. and It can be used for the defluorination and removal of perfluorinated compound pollutants in water bodies.

[0007] The technical solution of the present invention:

[0008] A method for preparing a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water comprises the following steps:

[0009] (1) Lithium fluoride is dissolved in concentrated hydrochloric acid under magnetic stirring to form a homogeneous solution; titanium aluminum carbide powder is gradually added to the homogeneous solution under heating and stirring conditions, and the Al layer in the titanium aluminum carbide is removed after etching for 24 hours, and the resulting solid residue is washed several times with distilled water; finally, the mixed solution is centrifuged and ultrasonically treated in an ice bath under an argon atmosphere to obtain a multilayer two-dimensional MXenes sheet suspension;

[0010] (2) Under magnetic stirring, a multilayer two-dimensional MXenes sheet suspension is dispersed in distilled water to form a uniform dispersion of MXenes; the uniform dispersion of MXenes and the ClCo2-6H2O solution are then ultrasonically treated under argon; under stirring, the ClCo2-6H2O solution is slowly added dropwise to the uniform dispersion of MXenes. After sufficient reaction, the Co-MXenes are precipitated with acetone for half an hour and collected by centrifugation. The product is dried under vacuum to obtain Co-MXenes;

[0011] (3) The Co-MXenes and ceramic balls obtained in step 2 are dispersed in ethanol and ball-milled to obtain a composite catalyst of Co-MXenes and alumina ceramic balls, which is a confined Fenton-like catalytic material.

[0012] In step (1), the mass ratio of lithium fluoride to titanium aluminum carbide in concentrated hydrochloric acid is 3:2, the molar concentration of concentrated hydrochloric acid is 12M, the concentration of lithium fluoride in concentrated hydrochloric acid is controlled to be 100g / L, and the ultrasonic time is 30 minutes.

[0013] In step (2), the molar concentration ratio of the multilayer two-dimensional MXenes sheet to ClCo2-6H2O in the reaction system is 5:(3-6).

[0014] In step (3), the mass ratio of Co-MXenes to alumina ceramic balls is 1:(5-10), wherein the ball milling condition of Co-MXenes is 500 rpm for 2-3 hours.

[0015] The application of the above-mentioned confined Fenton-like catalytic material in the oxidation and degradation of perfluorinated compound pollutants in water bodies is as follows:

[0016] Under stirring conditions, Co-MXenes, alumina ceramic ball composite catalyst and persulfate are added to the perfluorinated pollutant wastewater to be treated. The control conditions are: normal pressure, reaction temperature of 20-30°C; the input ratio of catalyst and persulfate in the reaction system is (2-6): (0.15-0.3), and the reaction is carried out at a rotation speed of 400rpm-500rpm for 1-6 hours to degrade the perfluorinated pollutants in the water.

[0017] The perfluorinated pollutant is perfluorooctanoic acid.

[0018] The persulfate is potassium peroxymonosulfate (PMS).

[0019] Working principle of the invention: The invention provides a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water, including a carrier and single-atom Co-MXenes loaded on the carrier; the carrier is an alumina ceramic ball; the mass of MXenes-Co is 6.4% of the carrier mass, wherein the multilayer MXenes sheet provides a confined reaction space of 1.5nm. When free radicals are generated in the confined interlayer, their hydration state is destroyed, the hydration coordination energy gap is lower, and they are converted into The energy barrier to SO5 increases, so SO5 can remain in solution and remain sufficiently reactive. After contacting with the CF bond at the head end of perfluorooctanoic acid, H / F exchange occurs, and then the carboxyl group formed by carboxylation is oxidized and removed by sulfate radicals. and The alternating effects achieve defluorination degradation and deep mineralization of perfluorinated pollutants.

[0020] The beneficial effects of the present invention are: a confined Fenton-like catalytic material for high-efficiency mineralization and removal of perfluorinated compounds in water. The preparation process of the confined single-atom Co-MXenes material is simple, and the amount of ClCo2-6H2O can be adjusted to achieve the loading amount of single-atom Co. At the same time, the confined single-atom material can retain the persulfate when activating free radicals, which enable them to react with perfluorinated compounds to defluorinate, allowing The oxidation of perfluorinated compounds is more efficient. Furthermore, the nano-confined space of MXenes can shield interference from organic macromolecules in the aqueous environment, maintaining efficient mineralization of perfluorinated compounds in complex wastewater. This process, which requires no external energy and achieves both reductive defluorination and oxidative removal in a single system, holds valuable implications for the treatment of wastewater containing perfluorinated pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 yes Figure 6The X-ray absorption near-edge structure (XANES) spectrum and extended X-ray absorption fine structure spectrum (EXAFS) spectrum of Co-MXenes-1 prepared in Example 1 are shown in Figure 1; wherein, a is the XANES spectrum of Co-MXenes-1, and b is the EXAFS spectrum of Co-MXenes-1;

[0022] Figure 2 1 is an X-ray diffractometer pattern (XRD) of the catalysts prepared in Example 1 of the present invention and Comparative Example 1;

[0023] Figure 3 These are scanning electron micrographs and transmission electron micrographs of the Co-MXenes and alumina ceramic ball composite catalysts prepared in Example 1 of the present invention and Comparative Example 1; wherein a is a scanning electron micrograph of Co-MXenes-1, and b is a transmission electron micrograph of S / Co-MXenes;

[0024] Figure 4 The electron paramagnetic resonance spectra of Co-MXenes-1 and S / Co-MXenes catalyst activated persulfate prepared in Example 1 of the present invention and Comparative Example 1, and the liquid phase retention diagram of hydroxyl radical probe terephthalic acid; wherein a is the free radical electron paramagnetic resonance spectrum, and b is the liquid phase product signal retention diagram after the reaction of terephthalic acid (TPA);

[0025] Figure 5 Figure 1 is a graph showing the degradation effects of Co-MXenes-1 and S / Co-MXenes catalysts prepared in Example 1 and Comparative Example 1 of the present invention on the removal of diphenylamine in 1-hexanol and benzoic acid in aqueous solution by activating persulfate; wherein a is a graph showing the degradation effects of removing diphenylamine (DPA) from 1-hexanol, and b is a graph showing the degradation effects of removing benzoic acid (BA) in aqueous solution;

[0026] Figure 6 The removal curves and defluorination curves of perfluorooctanoic acid degradation by persulfate activated by Co-MXenes-1, Co-MXenes-2, Co-MXenes-3 and S / Co-MXenes catalysts prepared in Examples 1, 2, 3 and Comparative Example 1 of the present invention are shown; wherein a is the perfluorooctanoic acid removal curve, and b is the defluorination rate of perfluorooctanoic acid.

[0027] Figure 7 The following are the removal and mineralization curves of three representative perfluorinated compounds degraded by activated persulfate in Example 1 of the present invention. Here, a is the removal curve of a representative perfluorinated compound, and b is the total organic carbon (TOC) removal rate and defluorination rate of the representative perfluorinated compound. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0029] Example 1

[0030] A method for preparing a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water comprises the following steps:

[0031] (1) Under magnetic stirring, 1.5 g of lithium fluoride was dissolved in 15 mL of concentrated hydrochloric acid. After a homogeneous solution was formed, 1 g of titanium aluminum carbide powder was gradually added and mixed with the solution. The solution was heated and stirred under magnetic stirring. The resulting solid residue was washed several times with distilled water. Finally, the mixture was centrifuged and ultrasonically treated in an ice bath under an argon atmosphere for 30 min to obtain multilayer two-dimensional MXenes sheets.

[0032] (2) A 2 g / L MXene suspension was dispersed in 50 mL of distilled water under magnetic stirring to form a clear solution. The MXene suspension and 50 mL of 7 mM ClCo2-6H2O were then ultrasonically treated under argon for 30 min. The ClCo2-6H2O solution was slowly added dropwise to the MXene under stirring. After sufficient reaction, the Co-MXenes were precipitated with acetone for half an hour and collected by centrifugation. The product was then dried under vacuum.

[0033] (3) 0.25 g of the Co-MXenes and 2.5 g of ceramic balls prepared in step (2) were dispersed in 50 mL of ethanol and ball-milled at 500 rpm for 2 h to obtain a composite catalyst of Co-MXenes and alumina ceramic balls, which is the catalytic material. Single-atom Co accounts for 6.8% of the MXene, and is designated as Co-MXenes-1.

[0034] Furthermore, the reactor containing the wastewater to be treated is placed on a stirring table, and the Co-MXenes and alumina ceramic ball composite catalyst and persulfate prepared in step (3) are added to the wastewater. The control conditions are: normal pressure, reaction temperature of 20-30°C; the amount of the MnO2 nanotube and alumina ceramic ball composite material prepared in step 4 in the reaction system is 6 g / L, the concentration of persulfate in the reaction system is 1 mM, and the reaction is carried out at a rotation speed of 400 rpm for 5 hours to oxidize and degrade organic pollutants in the water.

[0035] Example 2

[0036] This embodiment differs from Specific Example 1 in that the concentration of ClCo2-6H2O in step (2) is controlled to 5 mM, resulting in a catalytic material in which the Co-MXene content in the ceramic spheres is 5.3%, which is recorded as Co-MXenes-2. The rest of the process is the same as Specific Example 1.

[0037] Example 3

[0038] This embodiment differs from Specific Example 1 in that the concentration of ClCo2-6H2O in step (2) is controlled to 3 mM, resulting in a catalytic material in which the Co-MXene content in the ceramic spheres is 3.8%, which is recorded as Co-MXenes-3. The rest of the process is the same as Specific Example 1.

[0039] Example 4

[0040] This embodiment differs from Specific Example 1 in that the ball milling time in step (3) is controlled to 3 hours, resulting in a catalytic material in which the Co-MXene content in the ceramic balls is 8.9%, which is recorded as Co-MXenes-4. Other aspects are the same as Specific Example 1.

[0041] Example 5

[0042] This embodiment differs from Specific Example 1 in that the dosages of Co-MXenes and ceramic balls in step (3) are controlled to be 0.25 g and 1.25 g, respectively, to obtain a catalytic material having a Co-MXene content of 5.6% in the ceramic balls, which is designated as Co-MXenes-5. Other aspects are the same as Specific Example 1.

[0043] Example 6

[0044] This embodiment differs from Specific Example 1 in that the dosages of Co-MXenes and ceramic balls in step (3) are controlled to be 0.25 g and 1.75 g, respectively, to obtain a catalytic material having a Co-MXene content of 5.9% in the ceramic balls, which is designated as Co-MXenes-6. The remainder of the process is the same as Specific Example 1.

[0045] Comparative Example 1

[0046] A method for preparing a non-confined Fenton-like catalytic material for treating perfluorinated compounds in water comprises the following steps:

[0047] This embodiment differs from Specific Example 1 in that the Co-MXenes dispersion obtained in step (2) is continuously stirred at 35°C for 30 minutes, then ultrasonically treated in an ice bath under an argon atmosphere for 2 hours, and centrifuged at 6000 rpm for 20 minutes. The above process is repeated three times and freeze-dried to obtain a single-layer Co-MXene structure, denoted as S / Co-MXenes. Other aspects are the same as Specific Example 1.

[0048] The present invention is verified by the following test:

[0049] Experiment 1: This experiment was to detect the active species produced by persulfate activation of Co-MXenes and S / Co-MXenes catalysts. 1 mL of 2 mM PMS mother liquor prepared in deionized water was added to 100 mL of perfluorooctanoic acid solution prepared in deionized water to a concentration of 0.02 mM perfluorooctanoic acid and 1 mM perfluorooctanoic acid, respectively. The solution was thoroughly mixed at 400 rpm in a mechanical stirrer. After adding 200 mg of catalyst, the timer was started. Samples were taken after 5 minutes of reaction. After passing through a 0.22 μm PES polyethersulfone membrane, 1 mL of the filtered sample was placed in a centrifuge tube. 2,2,6,6-tetramethyl-4-piperidinol (TEMP, >99%) was dissolved in phosphate buffer solution (pH = 7.4) to a final concentration of 50 mM. Then, 40 μL of the TEMP solution was mixed with the extracted 40 μL filtered sample. The mixed solution of TEMP is absorbed by the quartz capillary and the signal corresponding to singlet oxygen is detected from the spin-trapping adduct in EPR. The signal of singlet oxygen in EPR is as follows: Figure 4 As shown in a.

[0050] Experiment 2: This experiment is to detect the persulfate-specific probe experiment for the activation of Co-MXenes and S / Co-MXenes catalysts. The probe (TPA, BA and DPA) and PMS concentrations were configured to be 0.05mM and 0.5mM, respectively, and thoroughly mixed at 400rpm in a mechanical stirrer. After adding 200mg of catalyst, the timer was started, and samples were taken at intervals within 5 minutes. After passing through a 0.22μm PES polyethersulfone membrane, 1mL of the filtered sample was taken and placed in a centrifuge tube. TBA and BA were detected by high-performance liquid chromatography, and DPA was detected by UV-visible light analyzer.

[0051] Experiment 3: This experiment is to use the designed catalyst to activate the removal of perfluorinated pollutants in persulfate water, and compare the removal effects of confined catalysts with different single-atom contents (Co-MXenes-1, Co-MXenes-2 and Co-MXenes-3) and non-confined S / Co-MXenes on perfluorinated pollutants. 0.5 mL of 100 mM PMS mother liquor prepared with deionized water was added to 100 mL of perfluorooctanoic acid solution prepared with deionized water, so that the concentrations of perfluorooctanoic acid and PMS in the solution were 0.02 mM and 1 mM, respectively, and the mixture was thoroughly mixed at 400 rpm in a mechanical stirrer. After adding 200 mg of catalyst, the timing was started, and sampling was performed at different sampling times. After passing through a 0.22 μm PES polyethersulfone membrane, 1 mL of the filtered sample was placed in a centrifuge tube, and 0.5 mL of 10 mmol / L sodium thiosulfate was added to quench the sample. The sample was stored at low temperature (4 ° C) and the concentration of perfluorinated pollutants at different sampling times was determined by high performance liquid chromatography-mass spectrometry; the removal of fluoride ions and total organic carbon in the reaction was detected by ion chromatography and total organic carbon analyzer. The corresponding results are shown in Figure 2. Figure 6 、 7 shown.

[0052] Figure 1 a is the XANES spectrum of Co-MXenes-1 prepared in Example 1. XANES is used to study the electronic state of Co atoms. The results show that the valence state of Co in Co-MXenes-1 is between that of Co foil and Co3O4. This indicates that the Co species in Co-MXenes-1 are positively charged. Figure 1 b EXAFS measurement further confirms the chemical structure of Co atoms fixed on MXenes. No Co-Co bonds (present in the Co foil EXAFS spectrum) were detected nearby. There is a main peak at , which is related to the Co-O bonding configuration. The Co-O coordination number is 2.9 and the bond length is The above results clearly show that single-atom Co is successfully anchored in MXenes with Co-O3 coordination.

[0053] Figure 2It is an X-ray diffractometer diagram of the catalyst prepared in Example 1 of the present invention and Comparative Example 1; Co-MXenes nanosheets loaded with Co single atoms. The X-ray diffraction patterns of MXenes and Co-MXenes show that the interlayer spacing does not change after the introduction of Co single atoms. According to the Bragg equation (2dsinθ=nλ, where θ is the angle between the incident ray, the reflected ray and the reflected crystal plane, λ is the wavelength 0.1542, and n is the reflection order 1), the interlayer spacing of Co-MXenes and MXenens can be calculated to be 1.5nm. After repeated centrifugal ultrasound, the layered Co-MXenes structure is peeled off, and the 002 characteristic peak in the XRD of the corresponding MXenes almost disappears.

[0054] Figure 3 These are scanning electron microscope images and transmission electron microscope images of the Co-MXenes, S / Co-MXenes and alumina ceramic ball composite catalysts prepared in Example 1 and Comparative Example 1 of the present invention. Figure 3 b shows that the multilayer structure of Co-MXenes is accordion-shaped, and after the multilayer Co-MXenes are peeled off, Figure 3 Single-layer S / Co-MXenes are also clearly shown in b.

[0055] Figure 4 a is the electron paramagnetic resonance spectra of Co-MXenes-1 and S / Co-MXenes catalyst activated persulfate prepared in Example 1 of the present invention and Comparative Example 1. Both systems show strong mixed peaks of sulfate and hydroxyl radical signals. In order to distinguish specific free radical species, we use terephthalic acid, a specific probe for hydroxyl radicals, as the detection substance. The principle is that hydroxyl reacts with TPA to generate hydroxyterephthalic acid (hTPA), and the addition product can be detected in the liquid phase. Figure 4 b. To better illustrate the results, we used the classic Fenton system to generate hydroxyl radicals. The hTPA peak appeared at a liquid phase retention time of 10 minutes. However, the Co-MXenes-1 and S / Co-MXenes catalysts prepared in the examples and comparative examples were unable to generate hydroxyl radicals. Combined with the electron paramagnetic resonance results, it was shown that the above catalysts could only activate persulfate to produce sulfate radicals.

[0056] Figure 5 a is the curve of the removal of DPA in 1-hexanol by Co-MXenes-1 and S / Co-MXenes catalysts prepared in Example 1 of the present invention and Comparative Example 1, which can be used to detect the reducibility of PMS produced in the Haber-Weiss cycle. Shows sufficient reactivity with aromatic amines, among which The free radicals and OH hydroxyl groups were completely quenched in the organic solvent, and the characteristic signal peak of DPA at UV 285nm disappeared rapidly, indicating that However It is extremely unstable in aqueous solution and will be consumed through various side reactions. Free radicals are easily converted into like Figure 5 b. Benzoic acid (BA) is used as a free radical probe to quantify the free radical concentration in the reaction system. The BA kinetics induced by the S / Co-MXenes catalyst prepared in Comparative Example 1 is significantly better than that of the Co-MXenes-1 prepared in Example 1, which indicates that after the confined structure of Co-MXenes-1 is stripped off, Due to the hydration effect, it is quickly converted into Free radicals.

[0057] Figure 6 These are the removal curves and defluorination curves of perfluorooctanoic acid degradation by persulfate activated by Co-MXenes-1, Co-MXenes-2, Co-MXenes-3 and S / Co-MXenes catalysts prepared in Examples 1, 2, 3, 4 of the present invention and Comparative Example 1. The free radicals first undergo H / F exchange with perfluorooctanoic acid, inducing the CF bond to transform into a CH bond, resulting in an unstable perfluorocarbon chain structure. Free radicals are more likely to remove the carboxyl group in perfluorooctanoic acid, and the exposed CH bond is carboxylated in water to form a carboxyl group, which is then Oxidative removal. and The removal of perfluorooctanoic acid is completed by alternating action. Among them, as the catalyst content in Co-MXenes-1, Co-MXenes-2, and Co-MXenes-3 decreases successively, the efficiency of catalyst activation PMS in removing perfluorooctanoic acid and the defluorination rate also decrease successively. For Co-MXenes-4 prepared in Example 4, although a higher catalyst composite ratio is obtained, the excessively thick accumulation of Co-MXenes on the surface of the ceramic ball affects the mass transfer of the reaction solution, resulting in a worse catalytic performance than the catalyst prepared in Examples 1 and 2 with lower loading. When the S / Co-MXenes obtained by peeling off the confined structure in the comparative example, due to the generation of Disproportionately hydrated There is no chance to react with PFOA, and PFOA is difficult to remove by oxidation alone, even if S / Co-MXenes produces more The corresponding PFOA removal and defluorination rates were also extremely weak.

[0058] Figure 7a is the removal curve of three representative perfluorinated pollutants degraded by activated persulfate in Example 1 of the present invention. The structures of the other two representative perfluorinated compounds selected are perfluorooctane sulfonic acid (PFOS, with sulfonic acid group) and perfluoro-4-methoxybutyric acid (PFMA, with carbonyl and carboxyl groups). Although they have structural differences, they are both degraded in the Co-MXenes / PMS oxidation system. and Eliminate quickly. Figure 7 b. All three perfluorinated pollutants exhibited highly effective defluorination, and the corresponding TOC in the reaction system was also removed. This demonstrates that the confined single-atom catalysis designed in this invention effectively destroys perfluorinated pollutants under typical Fenton-like operation, paving a new path for the future development of advanced catalysts with nanostructured single-atom structures.

Claims

1. A method for preparing a confined Fenton-like catalytic material for high-efficiency mineralization removal of perfluorinated compounds in water, characterized in that: The steps include: (1) Lithium fluoride was dissolved in concentrated hydrochloric acid under magnetic stirring to form a homogeneous solution. Titanium aluminum carbide powder was gradually added to the homogeneous solution under heating and stirring conditions. After etching for 24 hours to remove the Al layer in the titanium aluminum carbide, the solid residue was washed several times with distilled water. Finally, the mixture was centrifuged and ultrasonically treated in an ice bath under an argon atmosphere to obtain a multilayer two-dimensional MXenes sheet suspension. (2) Under magnetic stirring, a multilayer two-dimensional MXenes sheet suspension is dispersed in distilled water to form a uniform dispersion of MXenes; the uniform dispersion of MXenes and the ClCo2-6H2O solution are then ultrasonically treated under argon; under stirring, the ClCo2-6H2O solution is slowly added dropwise to the uniform dispersion of MXenes. After sufficient reaction, the Co-MXenes are precipitated with acetone for half an hour and collected by centrifugation. The product is dried under vacuum to obtain Co-MXenes; (3) The Co-MXenes and ceramic balls obtained in step 2 are dispersed in ethanol and ball-milled to obtain a composite catalyst of Co-MXenes and alumina ceramic balls, which is a confined Fenton-like catalytic material.

2. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of lithium fluoride and titanium aluminum carbide in concentrated hydrochloric acid is (2-3): (1-2).

3. The preparation method according to claim 1, characterized in that In step (1), the molar concentration of concentrated hydrochloric acid is 12M.

4. The preparation method according to claim 1, characterized in that In step (1), the concentration of lithium fluoride in concentrated hydrochloric acid is controlled to be 100 g / L.

5. The preparation method according to claim 1, characterized in that In step (1), the ultrasonication time is 30 to 60 minutes.

6. The preparation method according to claim 1, characterized in that In step (2), the molar concentration ratio of the multilayer two-dimensional MXenes sheet to ClCo2-6H2O in the reaction system is 5:(3-6).

7. The preparation method according to claim 1, characterized in that In step (3), the mass ratio of Co-MXenes to alumina ceramic balls is (1-2): (3-5), wherein the ball milling condition of Co-MXenes is 500 rpm for 2-3 hours.

8. Use of the confined Fenton-like catalytic material obtained by the preparation method according to any one of claims 1 to 7 for oxidative degradation of perfluorinated compound pollutants in water, characterized in that: Here are the steps: Under stirring conditions, Co-MXenes, alumina ceramic ball composite catalyst and persulfate are added to the perfluorinated pollutant wastewater to be treated. The control conditions are: normal pressure, reaction temperature of 20~30℃; the reaction is carried out at a speed of 400rpm~500rpm for 1~6 hours to degrade the perfluorinated pollutants in the water.

9. The use of the method for oxidative degradation of perfluorinated compound pollutants in water according to claim 8, characterized in that: The input ratio of catalyst to persulfate in the reaction system is (2-6) g / L: (0.15-0.3) mmol.

10. The use of the method for oxidative degradation of perfluorinated compound pollutants in water according to claim 8, characterized in that: The perfluorinated pollutant is perfluorooctanoic acid, and the persulfate is potassium peroxymonosulfate.

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