Dual-atom catalyst screening method, and iron-vanadium dual-atom catalyst and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a dual-atom catalyst screening method, and an iron-vanadium dual-atom catalyst and a preparation method therefor and a use thereof. The screening method comprises: step S1, using adsorption energy and electron transfer quantity as descriptors for evaluating the capacity of a catalyst in adsorbing and activating PMS, performing first-step screening on single-atom-metal-supported M-MXenes according to the adsorption energies ranked in a descending order, obtaining the top n M-MXenes, and screening for n metals M; step S2, pairing the n metals M, and obtaining a dual-atom pair support, i.e., an M1-M2-MXene group; and step S3, performing differential charge calculation, and screening for M1-M2-MXene having the highest electron transfer quantity as a dual-atom catalyst. An MXene-based iron-vanadium dual-atom catalyst screened and prepared in the present invention is capable of activating PMS, exhibits high and stable removal rate and removal efficiency for bisphenol A (BPA), and can completely remove 20 mg / L BPA within 6 min, wherein the maximum reaction rate constant can reach 0.98 min-1. The screening process in the present invention is simple, is easy to control, has high practicability, and is suitable for efficient screening of dual-atom catalysts.

Description

A method for screening diatomic catalysts, an iron / vanadium diatomic catalyst, its preparation method and applications Technical Field

[0001] This invention belongs to the field of water purification technology, and relates to the application of catalysts and related mechanism research in advanced oxidation processes based on peroxymonosulfate. Specifically, it relates to a method for screening diatomic catalysts, an iron / vanadium diatomic catalyst, its preparation method and uses. Background Technology

[0002] With the global shortage of clean water resources becoming increasingly severe, the development of urban water purification technologies has become crucial. Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have shown great practical potential in the field of water purification because they can rapidly remove organic micropollutants from water by activating peroxymonosulfate (PMS) to generate a large number of reactive oxygen species. In PMS-AOPs, the performance of the catalyst is crucial for activating PMS, directly affecting the efficiency of reactive oxygen species generation and the removal effect of organic micropollutants.

[0003] Although single-atom catalysts (SACs) supported on transition metals (iron, copper, cobalt, manganese, etc.) have attracted widespread attention in Fenton-like reactions, their dispersed metal sites, easily tunable electronic structures, and identifiable coordination provide a foundation for studying structure-activity relationships, they have significant limitations in PMS activation. For example, PMS activation involves two key steps: adsorption and activation. The isolated active sites in SACs are difficult to satisfy the scaling relationships of multi-step reactions, which to some extent limits their activation efficiency for PMS and their ability to remove organic micropollutants.

[0004] Compared to SACs, diatomic catalysts (DACs) exhibit higher reactivity in Fenton-like reactions, and the synergistic effect between the two atomic sites provides more possibilities for the catalytic mechanism. However, they also face more complex electronic structure issues. Currently, the primary challenge in DAC research lies in how to accurately design cooperative diatomic pairs to achieve higher reactivity. Furthermore, the lack of suitable descriptors to effectively correlate experimental and theoretical results makes it difficult to explore their catalytic mechanisms and assess their activity, hindering the rapid and accurate screening of highly active diatomic pairs for practical water purification applications. Summary of the Invention

[0005] The purpose of this invention is to improve the efficiency and sustainability of urban water purification and solve the technical challenges of removing organic micropollutants from water. It provides a method for screening diatomic catalysts based on density functional theory calculations. Based on this method, an iron / vanadium diatomic catalyst is screened and prepared, and used to treat organic pollutants in BPA from water and photovoltaic wastewater effluent. The catalyst of this invention exhibits high removal efficiency for BPA and organic pollutants in photovoltaic wastewater effluent, and demonstrates good practicality and stability.

[0006] To achieve the above objectives, the present invention provides a method for screening diatomic catalysts, comprising the following steps:

[0007] Step S1: Using adsorption energy and electron transfer amount as descriptors to evaluate the catalyst's ability to adsorb and activate PMS, the M-MXenes loaded with single-atom metals are sorted from high to low adsorption energy for the first screening step, and the top n M-MXenes are obtained, thus obtaining n metals M.

[0008] Step S2: Pair the n metals M in pairs to obtain the diatomic pairing carrier M1-M2-MXene group;

[0009] Step S3: Perform differential charge calculation on the M1-M2-MXene group and screen out the M1-M2-MXene with the highest electron transfer amount as a diatomic catalyst.

[0010] Optionally, the single-atom metal comprises at least four of the following: iron, copper, cobalt, manganese, vanadium, nickel, and zinc.

[0011] Optionally, n is 3 or 4, and M1-M2-MXene is an iron / vanadium diatomic catalyst.

[0012] This invention also provides a method for preparing an iron / vanadium diatomic catalyst, comprising:

[0013] Step 1, Ti3C2T x MXene was dispersed in ultrapure water to obtain mixture I;

[0014] Step 2: Add FeCl3·6H2O and NH4VO3 to the mixture I and stir until homogeneous to obtain mixture II;

[0015] Step 3: Filter and dry the mixture II to obtain solid powder I;

[0016] Step 4: Place the solid powder I in a tube furnace and calcine it at high temperature under a protective atmosphere to obtain solid powder II;

[0017] Step 5: The solid powder II is acid-washed and water-washed several times until the solution pH > 6.5, filtered, and dried to obtain iron / vanadium diatomic catalyst powder.

[0018] Optionally, the FeCl3·6H2O and NH4VO3 are in a molar ratio of 1:(1-2).

[0019] Optionally, in step 4, the high-temperature calcination temperature is 500℃~900℃, and the heating rate is 3-10℃·min. -1 .

[0020] The present invention also provides an iron / vanadium diatomic catalyst, which is formed by supporting iron and vanadium in Ti3C2Tx MXene, wherein the molar ratio of iron to vanadium is 1:(1-2), and the molar ratio of Fe to Ti3C2Tx MXene is (0.25-1:1).

[0021] The present invention also provides an application of the above-mentioned iron / vanadium diatomic catalyst for treating bisphenol A in water or for treating photovoltaic wastewater.

[0022] Optionally, the method for treating bisphenol A in water includes: adding the iron / alum diatomic catalyst to the water to be treated and mixing it, then adding potassium persulfate to adjust the pH of the water to 3-11 and the water temperature to 293-313K; wherein the dosage of the iron / alum diatomic catalyst is 0.5-2.0 g / L.

[0023] Optionally, the method for treating photovoltaic wastewater includes: fixing the iron / vanadium diatomic catalyst in a filtration device, allowing photovoltaic wastewater mixed with potassium persulfate to pass through, and discharging the treated water.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention employs a screening method based on density functional theory calculations, using adsorption energy and electron transfer as primary descriptors to predict material properties. Based on these descriptors, iron / alum diatomic catalyst materials are screened. This screening method is simple, efficient, and low-cost. The stated iron / alum diatomic catalyst material exhibits high and stable efficiency in activating PMS and removing BPA contaminants within a pH range of 3-11 in water, achieving a removal rate of 100% within 6 minutes and a reaction rate constant of 0.98 min. -1 .

[0026] Furthermore, the composite material described in this invention exhibits good stability. The Fe-V-MXene / PVDF / PMS system developed based on this catalyst still achieves a removal rate of over 70% after 8 hours of continuous flow treatment of photovoltaic wastewater effluent. Attached Figure Description

[0027] Figure 1 shows the calculated adsorption energy and electron transfer diagrams of various M-MXenes; where (a) represents the adsorption energy diagram of PMS on MXene supports with different metal atoms, and (b) represents the electron transfer diagram between various metals and PMS.

[0028] Figure 2 shows the charge density difference diagram for the calculation implementation.

[0029] Figure 3 shows the atomic local structure and chemical state of Fe-V-MXene. (a) represents the normalized XANES spectrum of Fe; (b) represents the Fourier transform k-values ​​of Fe-V-MXene and the reference samples (FeO, Fe₂O₃, Fe₃O₄, Fe foil). 3 (c) shows the fitted data of Fe element in Fe-V-MXene in Figure (b); (d) shows the normalized XANES spectrum of V element in R space (a schematic diagram of the position of V in space); (e) shows the Fourier transform k of Fe-V-MXene and reference samples (VO2, V2O3, V2O5, V foil (vanadium foil)). 3 Weighted EXAFS data, (f) is the fitted data of V element in Fe-V-MXene in (e) of the figure, and (g)-(j) represent the k of Fe-V-MXene and the reference sample. 3 Wavelet transform of weighted EXAFS data.

[0030] Figure 4 shows the XRD pattern of Fe-V-MXene.

[0031] Figure 5 shows the FT-IR spectrum of Fe-V-MXene.

[0032] Figure 6 shows the removal efficiency of BPA by Fe-V-MXene activated PMS under different pH conditions in Examples 6-12;

[0033] Figure 7 shows the removal efficiency of PMS by Fe-V-MXene under different catalyst dosages in Examples 13-15 for BPA removal.

[0034] Figure 8 shows the experimental flowchart of the Fe-V-MXene / PVDF system.

[0035] Figure 9 shows the operating efficiency of the Fe-V-MXene / PVDF system for photovoltaic wastewater effluent. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Fenton-like reactions are extensions and improvements of the traditional Fenton reaction. The traditional Fenton reaction refers to the reaction under acidic conditions where ferrous ions (Fe...) react to react. 2+ The process involves the reaction of hydrogen peroxide (H₂O₂) to produce hydroxyl radicals (·OH) and other reactive oxidizing agents. The Fenton-like reaction, however, achieves a similar oxidation process under broader conditions, utilizing different catalysts or triggering mechanisms to generate highly oxidizing free radicals, thereby degrading various organic pollutants. The Fenton-like reaction is an advanced oxidation technology with wide applications in environmental protection and medicine.

[0040] The core idea of ​​density functional theory (DFT) is to express the properties of a system as a function of electron density. In quantum mechanics, solving the Schrödinger equation for multi-electron systems is extremely complex, while DFT greatly simplifies the calculation by expressing the system's energy as a functional of electron density. Specifically, the total energy of a system can be divided into several parts: kinetic energy, inter-electron interaction energy, and external potential energy (interaction between atomic nuclei and electrons). The expressions for the system's ground-state electron density and energy can be obtained using variational methods. DFT introduces exchange-correlation functionals to describe the complex interactions between electrons. The application of DFT involves the following steps: 1) Selecting a suitable exchange-correlation functional based on the nature and precision requirements of the research problem; 2) Constructing a system model: First, determining the geometric and electronic structure of the system under study. For Fenton-like reactions, a catalyst model can be constructed, including its crystal structure and surface structure. Simultaneously, the adsorption of reactants (such as H₂O₂, organic pollutants, etc.) on the catalyst surface needs to be considered. Then, quantum chemistry software, such as VASP and Gaussian, is used to model and calculate the system. During modeling, it is necessary to set appropriate calculation parameters, such as basis sets and cutoff energies, to ensure the accuracy and efficiency of the calculations. 3) Perform calculations and analysis: Utilize density functional theory to calculate the energy, electron density, charge distribution, and other properties of the system. By analyzing these properties, the mechanism of Fenton-like reactions can be revealed, such as the electron transfer process on the catalyst surface and the determination of active sites. For Fenton-like reactions, descriptors can be calculated, such as OO bond lengths, adsorption energies, charge transfer, and d-band centers. These descriptors can help us understand the activity and selectivity of the catalyst, as well as the kinetics and thermodynamic processes of the reaction.

[0041] In the field of Fenton-like reactions, although density functional theory calculations have been widely used for mechanism exploration, and numerous descriptors (such as O / O bond lengths, adsorption energies, charge transfer, and d-band centers) are frequently used to reveal catalytic mechanisms, existing descriptors still cannot fully correlate with experimental results in this field due to the complex electronic structure and reaction mechanisms of diatomic catalysts (DACs). Furthermore, these descriptors are often only used in research to describe mechanisms, and are rarely studied in catalyst design. Therefore, in the Fenton-like field, there is still a lack of methods and practices for predicting the activity of diatomic catalysts using density functional theory calculations, thus hindering the development of highly efficient catalysts.

[0042] Therefore, the present invention provides a specific process for screening Fe-V-MXene materials, comprising the following steps:

[0043] Step S1 involves using adsorption energy and the amount of electron transfer between the support and persulfate molecules as the main descriptors for evaluating the catalyst's ability to adsorb and activate PMS. M-MXenes loaded with single-atom metals are sorted by adsorption energy from high to low for the first screening step, obtaining the top n M-MXenes, thus identifying n metals M. In some embodiments, the single-atom metals include at least four of the following: iron, copper, cobalt, manganese, vanadium, nickel, and zinc.

[0044] Step S2 involves pairing the n metals M in pairs to obtain a biatomic pairing support group M1-M2-MXene. In this example, V, Mn, and Fe, which rank among the top three in adsorption energy, are paired in pairs to obtain bimetallic atom groups containing V-Mn, V-Fe, and Mn-Fe.

[0045] Step S3 involves performing differential charge calculations on the M1-M2-MXene group to screen out the M1-M2-MXene with the highest electron transfer capacity as a diatomic catalyst. Specifically, M1-M2-MXene with high adsorption energy or high electron transfer between the support and persulfate molecules is considered a potential high-efficiency catalyst. The high-efficiency electron transfer between the diatoms is further analyzed using charge density difference and differential charge (i.e., the charge after PMS adsorption minus the charge before adsorption), thus screening out highly active diatomic catalysts, namely, iron / vanadium diatomic catalysts.

[0046] Figure 1(a) shows the adsorption energy diagram of PMS on the MXene support with different metal atoms loaded on it, and Figure 1(b) shows the density of states diagram of the support and PMS.

[0047] As shown in Figure 1(a), the adsorption energies of MXene loaded with PMS by V, Mn, Fe, Co, Cu, Ni, and Zn are -4.01, -3.91, -3.62, -3.06, -2.61, -2.83, and -3.52 eV, respectively. Subsequently, three atoms (V, Mn, and Fe) were selected for further diatomic loading calculations due to their higher adsorption energies. Ultimately, Fe-V-MXene exhibited the highest adsorption energy (-5.33 eV), indicating that this structure possesses the highest PMS adsorption energy. The activation ability of the catalyst was further evaluated using Bader charge analysis via charge transfer, as shown in Figure 1(b). Fe-V-MXene exhibited the highest charge transfer value of 2.60|e|, significantly higher than both Fe-MXene and V-MXene, thus selecting the Fe-V diatomic catalyst.

[0048] The charge density difference further reveals charge transfer between different metal sites. Figure 2 shows the charge density difference (i.e., differential charge density) plots for V-MXene-PMS, Fe-MXene-PMS, and Fe-MXene-PMS. As shown in Figure 2, stronger chemical interactions involving charge transfer are observed around the Fe-V diatoms and PMS molecules in Fe-V-MXene-PMS. Furthermore, the charge density near the iron atom (Fe-MXene-PMS) is significantly enhanced, and V-MXene-PMS exhibits similar results (Figure 2). However, the formation of Fe-V diatomic sites significantly alters the charge density difference. The charge density near the Fe-V diatomic region exhibits a bipolar distribution, with an electron accumulation region forming near the Fe atom and an electron depletion region forming near the V atom. This indicates that with the redistribution of electrons, electrons from the V atom further transfer to the Fe atom, which is conducive to coordination between the Fe-V diatoms and promotes the catalytic reaction. In this example, an iron / vanadium (Fe-V) diatomic catalyst was screened.

[0049] The present invention provides an iron / vanadium diatomic catalyst (Fe-V-MXene) with the atomic local structure and chemical state shown in Figure 3. In Figure 3, (a) represents the normalized XANES spectrum of Fe; and (b) represents the Fourier transform k-values ​​of Fe-V-MXene and reference samples (FeO, Fe2O3, Fe3O4, and Fe foil). 3 (c) shows the fitted data of Fe element in Fe-V-MXene in Figure (b); (d) shows the normalized XANES spectrum of V element in R space (a schematic diagram of the position of V in space); (e) shows the Fourier transform k of Fe-V-MXene and reference samples (VO2, V2O3, V2O5, V foil (vanadium foil)). 3 Weighted EXAFS data, (f) is the fitted data of V element in Fe-V-MXene in (e) of the figure, and (g)-(j) represent the k of Fe-V-MXene and the reference sample. 3 The wavelet transform of the weighted EXAFS data reveals the fitted k-space curves, showing the atomic pairing of Fe-V-MXene.

[0050] As shown in Figure 3(a), the K-edge absorption threshold of Fe in Fe-V-MXene is between FeO and Fe2O3, indicating that the valence state of Fe in Fe-V-MXene is between +2 and +3. The Fourier transform (FT) of Fe K-edge... 3The weighted EXAFS image, see Figure 3(c), shows two peaks at 1.7 and 2.6, corresponding to Fe-O and Fe-V, respectively. Furthermore, the VK edge absorption threshold of Fe-V-MXene is closer to the standard reference V₂O₃ (Figure 3d), indicating that V in Fe-V-MXene is in the oxidized state. Additionally, k is shown in Figures 3(g)-(j). 3 Wavelet transforms of the weighted EXAFS data show that the Fe-V sites in Fe-V-MXene are well-paired and well-distributed. These results confirm the good dispersion of Fe and V atoms on the Fe-V-MXene surface.

[0051] Figure 4 shows the XRD patterns of Fe-Mxene, V-MXene, and Fe-V-MXene. In the XRD patterns, Fe-V-MXene exhibits a peak surface similar to that of V-MXene, indicating that the overall structure of Fe-V-MXene is more similar to that of V-MXene.

[0052] Figure 5 shows the FT-IR spectrum, in which characteristic peaks of oxygen-containing functional groups -OH, C=O, and Ti-O were detected. This indicates that oxygen-containing functional groups are widely present on the MXene surface, which is beneficial for the coordination and fixation of Fe and V atoms.

[0053] The present invention also provides a method for preparing the iron / vanadium diatomic catalyst material, comprising the following steps:

[0054] Step 1: Disperse 400 mg Ti3C2Tx MXene in 200 mL of ultrapure water and sonicate to obtain mixture I;

[0055] Step 2: Add a certain mass of FeCl3·6H2O and NH4VO3 to mixture I and stir until homogeneous to obtain mixture II;

[0056] Step 3: After filtering the mixture II, dry it under vacuum at 60°C in a vacuum drying oven to obtain solid powder I;

[0057] Step 4: Place solid powder I in a tube furnace and heat it at 5°C / min under a protective atmosphere (nitrogen in this example). -1 After the heating rate is increased to a certain temperature, it is held for 2 hours to obtain solid powder II; the purpose of the protective atmosphere is to isolate oxygen and prevent the carbon in the material from being oxidized and lost.

[0058] Step 5: Wash solid powder II with 0.2M HCl solution, then sonicate at 25°C (300W, 25kHz) for 4 hours; then wash the product several times with ethanol and ultrapure water until the solution pH>6.5, filter, and vacuum dry at 60°C to finally obtain the iron / vanadium diatomic catalyst.

[0059] In some embodiments, the mass of FeCl3·6H2O and NH4VO3 is 0.166-1.66 g and 0.072-0.72 g, respectively, and the heating temperature is 500-900℃.

[0060] The present invention also provides a method for treating bisphenol A in water, wherein the iron / vanadium diatomic catalyst is first added and mixed evenly, and then PMS is added.

[0061] In some embodiments, the pH of the water is 3 to 11, and the water temperature is 293 to 313 K; the dosage of the composite material is 0.5 to 2.0 g / L.

[0062] This invention also provides a method for deep treatment of photovoltaic wastewater effluent. The method comprises: fixing the iron / vanadium diatomic catalyst in a filtration device, allowing photovoltaic wastewater mixed with potassium persulfate to pass through, thus completing the photovoltaic wastewater treatment, and discharging the treated water. In some embodiments, the iron / vanadium diatomic catalyst is placed in a columnar reactor (filtration device), with PVDF membranes fixed at the top and bottom of the reactor, respectively. Potassium persulfate is added to the photovoltaic wastewater, mixed thoroughly, and then enters the reactor from the top, with water exiting from the bottom. The PVDF membrane is used to fix the iron / vanadium diatomic catalyst so that the photovoltaic wastewater can pass through the catalyst uniformly.

[0063] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0064] Unless otherwise specified, all raw materials and reagents used in the embodiments of this invention are commercially available. Specifically, Ti3C2Tx MXene was purchased from Shanghai Maclean's Biochemical Technology Co., Ltd.

[0065] Example 1

[0066] 1. Screening of diatomic catalysts

[0067] Adsorption energy and the amount of electron transfer between the support and persulfate molecules were considered as the main descriptors for evaluating the catalyst's ability to adsorb and activate PMS. A first-step screening was performed on M-MXenes supported on single-atom metals (V, Mn, Fe, Co, Cu, Ni, Zn). M-MXenes (V, Mn, Fe) with the highest adsorption energy or the amount of electron transfer between the support and persulfate molecules were considered potential diatomic pairing options. Further, new diatomic paired supports, M1-M2-MXenes, were obtained through two pairing methods. M1-M2-MXenes with the highest adsorption energy or the amount of electron transfer between the support and persulfate molecules were considered potential high-efficiency catalysts. The efficient electron transfer between diatoms was further analyzed using charge density difference and differential charge, and the highly active diatomic catalyst Fe-V-MXene was screened.

[0068] 2. Synthesis of Fe-V-MXene

[0069] (1) Disperse 400 mg Ti3C2Tx MXene in 200 mL of ultrapure water and sonicate to obtain mixture I;

[0070] (2) Add 0.83g of FeCl3·6H2O and 0.36g of NH4VO3 to mixture I and stir until homogeneous to obtain mixture II;

[0071] (3) After filtering the mixture II, it was vacuum dried at 60°C in a vacuum drying oven to obtain solid powder I;

[0072] (4) Solid powder I was placed in a tube furnace and heated to 600°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 2 hours to obtain solid powder II.

[0073] (5) Solid powder II was washed with 0.2M HCl solution, then ultrasonically treated at 25°C (300W, 25kHz) for 4 hours, and then washed with ethanol and ultrapure water several times until the solution pH>6.5. The product was then filtered and vacuum dried at 60°C to finally obtain the iron / vanadium diatomic catalyst.

[0074] Example 2

[0075] 1. The screening of diatomic catalysts is the same as in Example 1.

[0076] 2. Synthesis of Fe-V-MXene

[0077] (1) Disperse 400 mg Ti3C2Tx MXene in 200 mL of ultrapure water and sonicate to obtain mixture I;

[0078] (2) Add 1.66g of FeCl3·6H2O and 0.72g of NH4VO3 to mixture I and stir until homogeneous to obtain mixture II;

[0079] (3) After filtering the mixture II, it was vacuum dried at 60°C in a vacuum drying oven to obtain solid powder I;

[0080] (4) Solid powder I was placed in a tube furnace and heated to 600°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 2 hours to obtain solid powder II.

[0081] (5) Solid powder II was washed with 0.2M HCl solution, then ultrasonically treated at 25°C (300W, 25kHz) for 4 hours, and then washed with ethanol and ultrapure water several times until the solution pH>6.5. The product was then filtered and vacuum dried at 60°C to finally obtain the iron / vanadium diatomic catalyst.

[0082] Example 3

[0083] 1. The screening of diatomic catalysts is the same as in Example 1.

[0084] 2. Synthesis of Fe-V-MXene

[0085] (1) Disperse 400 mg Ti3C2Tx MXene in 200 mL of ultrapure water and sonicate to obtain mixture I;

[0086] (2) Add 0.83g of FeCl3·6H2O and 0.36g of NH4VO3 to mixture I and stir until homogeneous to obtain mixture II;

[0087] (3) After filtering the mixture II, it was vacuum dried at 60°C in a vacuum drying oven to obtain solid powder I;

[0088] (4) Solid powder I was placed in a tube furnace and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 2 hours to obtain solid powder II.

[0089] (5) Solid powder II was washed with 0.2M HCl solution, then ultrasonically treated at 25°C (300W, 25kHz) for 4 hours, and then washed with ethanol and ultrapure water several times until the solution pH>6.5. The product was then filtered and vacuum dried at 60°C to finally obtain the iron / vanadium diatomic catalyst.

[0090] Example 4

[0091] 1. The screening of diatomic catalysts is the same as in Example 1.

[0092] 2. Synthesis of Fe-V-MXene

[0093] (1) Disperse 400 mg Ti3C2Tx MXene in 200 mL of ultrapure water and sonicate to obtain mixture I;

[0094] (2) Add 0.83g of FeCl3·6H2O and 0.36g of NH4VO3 to mixture I and stir until homogeneous to obtain mixture II;

[0095] (3) After filtering the mixture II, it was vacuum dried at 60°C in a vacuum drying oven to obtain solid powder I;

[0096] (4) Solid powder I was placed in a tube furnace and heated to 600°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 2 hours to obtain solid powder II.

[0097] (5) Solid powder II was washed with 0.2M HCl solution, then ultrasonically treated at 25°C (300W, 25kHz) for 4 hours, and then washed with ethanol and ultrapure water several times until the solution pH>6.5. The product was then filtered and vacuum dried at 60°C to finally obtain the iron / vanadium diatomic catalyst.

[0098] Treatment of Bisphenol A (BPA) in water bodies

[0099] BPA determination: The concentration of BPA was determined by high performance liquid chromatography (HPLC). Detection parameters: wavelength 278 nm, mobile phase methanol-deionized water (70:30, v / v), flow rate 1.0 mL / min. -1 The injection volume was 50 μL. All degradation experiments were conducted in a batch reactor using 150 mL Erlenmeyer flasks with magnetic stirring at 25 °C. First, 25 mg of catalyst (0.5 g·L⁻¹) was added. -1 Add 50 mL of BPA (20 mg·L⁻¹) -1 The solution was added to 2 mM PMS, and then the conical flask was placed on a constant temperature shaker at a speed of 170 rad·min. -1 The initial pH of the solution was adjusted using H₂SO₄ and / or NaOH solution. Subsequently, the reaction solution was sampled at regular intervals and filtered through a 0.45 μm membrane filter. Because PMS continuously generates free radicals that further oxidize and interfere with the measurement data, in some embodiments, Na₂S₂O₃ solution (0.1 M) was added to the solution as an inhibitor to prevent continued oxidation.

[0100] Example 5: Treatment of BPA in water

[0101] The initial pH of the solution was adjusted to 3 using H₂SO₄ solution. BPA concentration was measured every 1 minute, and the concentration was 0 mg / L after 5 minutes.-1 The calculated removal efficiency is 100%.

[0102] Example 6: Treatment of BPA in water

[0103] The initial pH of the solution was adjusted to 5 using H₂SO₄ solution. BPA concentration was measured every 1 minute, and the concentration was 0 mg / L after 5 minutes. -1 The calculated removal efficiency is 100%.

[0104] Example 7: Treatment of BPA in water

[0105] The initial pH of the solution was adjusted to 7 using H₂SO₄ and NaOH solutions. BPA concentration was measured every 1 minute, and after 5 minutes, the BPA concentration was 0.27 mg·L⁻¹. -1 The calculated removal efficiency is 98.9%.

[0106] Example 8: Treatment of BPA in water

[0107] The initial pH of the solution was adjusted to 9 using NaOH solution. BPA concentration was measured every 1 minute, and the concentration was 0 mg / L after 5 minutes. -1 The calculated removal efficiency is 100%.

[0108] Example 9: Treatment of BPA in water

[0109] The initial pH of the solution was adjusted to 11 using NaOH solution. BPA concentration was measured every 1 minute, and after 5 minutes, the BPA concentration was 0.49 mg·L⁻¹. -1 The calculated removal efficiency is 97.6%.

[0110] Figure 6 shows the removal efficiency of bisphenol A (BPA) by Fe-V-MXene in PMS activated in Examples 5-9. The figure shows that the initial solution pH has a relatively limited effect on BPA removal in the Fe-V-MXene / PMS system. As shown in Figure 6, Fe-V-MXene exhibits significant catalytic activity over a wide pH range (3.0-11.0). Within the initial pH range of 3.0-9.0, the BPA removal efficiency remained above 98% after 5 minutes, with a corresponding reaction rate constant (k...). obs The value ranges from 0.98 to 1.25 min. -1 However, at a solution pH of 11, BPA degradation was observed to be slightly inhibited, k obs Reduced to 0.82 min -1 This inhibition is mainly attributed to the presence of HSO5 under strongly alkaline conditions. - Converted to SO5 2-And the conversion of BPA molecules into BPA - (pKa = 9.6), thus hindering the catalytic process.

[0111] Example 10: Treatment of BPA in water

[0112] All degradation experiments were conducted in a batch reactor using 150 mL Erlenmeyer flasks with magnetic stirring at 25 °C. First, 25 mg of catalyst (0.5 g·L⁻¹) was added... -1 Add 50 mL of BPA (20 mg·L⁻¹) -1 The solution was added to 2 mM PMS, and then the conical flask was placed on a constant temperature shaker at a speed of 170 rad·min. -1 Subsequently, the reaction solution was sampled at regular intervals and filtered through a 0.45 μm membrane filter. Na₂S₂O₃ solution (0.1 M) was added to the solution to prevent continuous oxidation. The BPA concentration was measured to be 0.27 mg·L⁻¹ after 5 minutes. -1 The calculated removal efficiency is 98.9%.

[0113] Example 11: Treatment of BPA in water

[0114] Same as Example 10, except that the catalyst dosage is 0.25 g·L⁻¹. -1 The BPA concentration was measured to be 2.11 mg·L⁻¹ after 5 minutes. -1 The calculated removal efficiency is 89.5%.

[0115] Example 12: Treatment of BPA in water

[0116] Same as Example 10, except that the catalyst dosage is 1.0 g·L⁻¹. -1 The BPA concentration was measured to be 0 mg·L⁻¹ after 5 minutes. -1 The calculated removal efficiency is 100%.

[0117] Figure 7 shows the removal efficiency of Fe-V-MXene on BPA by activated PMS in Examples 10-12, where C t The concentration changes over time, with C0 representing the initial concentration. The graph shows that the catalyst dosage was increased from 0.25 g·L⁻¹. -1 Increase to 1 g·L -1 While keeping the PMS dosage constant, the removal efficiency was significantly improved, with kobs decreasing from 0.45 min. -1 Increased to 1.39 min -1 This improvement is attributed to the increase in active sites after catalyst addition, which promotes the generation of more active species.

[0118] Example 13: Deep treatment of photovoltaic wastewater effluent

[0119] Continuous flow experiments were conducted using photovoltaic wastewater effluent. Specific water samples were taken from the secondary sedimentation tank effluent of the industrial wastewater treatment plant in the Zero-Carbon Industrial Park of the Mengsu Economic Development Zone, Ordos City. The continuous flow experiment was carried out in a column reactor with a diameter of 3 cm at a reaction temperature of 25℃. As shown in Figure 8, the catalyst was highly dispersed and vacuum filtered onto a polyvinylidene fluoride (PVDF) membrane to assemble a continuous flow treatment device, which was used for further advanced treatment of the photovoltaic wastewater effluent. The continuous flow treatment device comprises, from bottom to top, a supporting substrate IV, a PVDF membrane III, a Fe-V-MXene II, and a PVDF membrane I.

[0120] Photovoltaic wastewater mainly contains organic matter (such as polyethylene glycol) and various inorganic ions (F... - Cl - (etc.), which are difficult to biodegrade and present significant challenges in practical treatment. Specific experimental results are shown in Figure 9; the effluent flow rate from the Fe-V-MXene / PVDF membrane was maintained at 80–100 L·m⁻¹. -2 ·h -1 After an 8-hour long-term test, the actual effluent showed a COD removal rate of >70% and a TOC removal rate of >45%. This result demonstrates the good long-term stability and practical application potential of Fe-V-MXene.

[0121] In this invention, the composite material adsorbs and removes Cd. 2+ The effective pH range is 4 to 7, which is close to the pH value of cadmium-polluted water, so this adsorbent can be used for the treatment of actual water bodies.

[0122] Example 14: Comparison with similar catalysts

[0123] Table 1: Parameters compared with similar catalysts

[0124] Note: The references in Table 1 are:

[0125] [1]

[0126] [2]X.Chen,F.O.Gudda,X.Hu,M.G.Waigi,Y.Gao,Degradation of bisphenol A in an oxidation system constructed from Mo2C MXene and peroxymonosulfate,npj Clean Water,5(2022)66.

[0127] [3]Y.Long,Z.Cao,W.Wu,W.Liu,P.Yang,X.Zhan,R.Chen,D.Liu,W.Huang,Rational modulation of Fe single-atom electronic structure in a Fe-N2B4 configuration for preferential 1O2 generation in Fenton-like reactions,Applied Catalysis B-Environment and Energy,344(2024).

[0128] [4]Y.Liu,R.Luo,Y.Li,J.Qi,C.Wang,J.Li,X.Sun,L.Wang,Sandwich-like Co3O4 / MXene composite with enhanced catalytic performance for Bisphenol A degradation,Chemical Engineering Journal,347(2018)731-740.

[0129] [5]P.Yang,Z.Cao,Y.Long,D.Liu,W.Huang,S.Zhan,M.Li,Regulating the Local Electronic Structure of Copper Single Atoms with Unsaturated B,O-Coordination for Selective 1O2 Generation,ACS Catalysis,13(2023)12414-12424.

[0130] [6]P.Yang,S.Li,L.Xiaofu,A.Xiaojing,D.Liu,W.Huang,Singlet oxygen-dominated activation of peroxymonosulfate by CuO / MXene nanocomposites for efficient decontamination of carbamazepine under high salinity conditions:Performance and singlet oxygen evolution mechanism,Separation and Purification Technology,285(2022)120288.

[0131] [7]Q.Zhou,P.Hong,X.Shi,Y.Li,K.Yao,W.Zhang,C.Wang,J.He,K.Zhang,L.Kong,Efficient degradation of tetracycline by a novel nanoconfinement structure Cu2O / Cu@MXene composite,Journal of Hazardous Materials,448(2023)130995.

[0132] [8]X.Cui,S.-S.Zhang,Y.Geng,J.Zhen,J.Zhan,C.Cao,S.-Q.Ni,Synergistic catalysis by Fe3O4-biochar / peroxymonosulfate system for the removal of bisphenol a,Separation and Purification Technology,276(2021)119351.

[0133] [9]Z.Yang,Z.Wang,G.Liang,X.Zhang,X.Xie,Catalyst bridging-mediated electron transfer for nonradical degradation of bisphenol A via natural manganese ore-cornstalk biochar composite activated peroxymonosulfate,Chemical Engineering Journal,426(2021)131777.

[0134]

[0010] Z.Zhang,H.Ding,Y.Li,J.Yu,L.Ding,Y.Kong,J.Ma,Nitrogen-doped biochar encapsulated Fe / Mn nanoparticles as cost-effective catalysts for heterogeneous activation of peroxymonosulfate towards the degradation of bisphenol-A:Mechanism insight and performance assessment,Separation and Purification Technology,283(2022)120136.

[0135]

[0011] X.Wang,W.Li,L.Yang,G.Zhao,J.Zhang,Q.Zhao,Phytic acid-modulated iron phosphide / biochar catalyst activates persulfate for rapid sulfamethoxazole removal:Synergy between iron phosphides and biochar,Chemical Engineering Journal,472(2023)144897.

[0136]

[0012] P.Zhang, X.Tan, S.Liu, Y.Liu, G.Zeng, S.Ye, Z.Yin,

[0137]

[0013] C.Wang, X.Wang, W.Wu, Y.Zong, Z.Zhang, Y.Li, S.Qin, F.Wang, Technology,323(2023)124302.

[0138] As shown in Table 1, the Fe-V-MXene prepared in this application exhibits strong PMS activation performance. This also demonstrates the feasibility and superiority of the screening method described in this invention. The density functional theory calculation method for screening diatomic catalysts described in this invention demonstrates a highly efficient screening principle. Based on this method, the iron / vanadium diatomic catalyst prepared using MXene as a substrate for PMS activation exhibits high and stable removal rates and efficiencies for bisphenol A within a water pH range of 3-11. (The text also mentions Fe3O4@MXene (0.039 min...), but the connection to the preceding sentence is unclear and requires further context.) -1 ), Mo2C MXene (0.023 min) -1 ), FeNx-B-2Mxene (0.25min) -1 Cu-SA / B-MXene-4 (0.23 min) -1Compared to other catalytic materials, Fe-V-MXene can completely remove 20 mg / L of BPA within 6 minutes, with a maximum reaction rate constant of 0.98 min. -1 Furthermore, it exhibits good anti-interference ability and long-term stability in recalcitrant photovoltaic wastewater.

[0139] In summary, the adsorption energy and charge transfer parameters of this invention are used as descriptors to correspond to the adsorption and activation stages of PMS. The adsorption energy is only used for pre-screening; the actual evaluation also incorporates charge transfer capability, and the performance of the d-band centers and density of states of different diatomic catalysts is further analyzed. The catalyst material of this invention exhibits good stability; after five regeneration tests, the removal rate of BPA remains above 90%. Furthermore, the Fe-V-MXene / PMS / PVDF system developed based on the Fe-V-MXene catalyst shows good application potential for the deep treatment of photovoltaic wastewater, with a TOC treatment efficiency still above 45% after 8 hours of stable operation. Overall, the Fe-V-MXene prepared in this application requires less complex procedures and has a broad reaction range, demonstrating promising application prospects.

[0140] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for screening diatomic catalysts based on density functional theory calculations, characterized in that, Includes the following steps: Step S1: Using adsorption energy and electron transfer amount as descriptors to evaluate the catalyst's ability to adsorb and activate PMS, the M-MXenes loaded with single-atom metals are sorted from high to low adsorption energy for the first screening step, and the top n M-MXenes are obtained, thus obtaining n metals M. Step S2: Pair the n metals M in pairs to obtain the diatomic pairing carrier M1-M2-MXene group; Step S3: Perform differential charge calculation on the M1-M2-MXene group and screen out the M1-M2-MXene with the highest electron transfer amount as a diatomic catalyst.

2. The method for screening diatomic catalysts based on density functional theory calculations as described in claim 1, characterized in that, The single-atom metal includes at least four of the following: iron, copper, cobalt, manganese, vanadium, nickel, and zinc.

3. The method for screening diatomic catalysts based on density functional theory calculations as described in claim 1, characterized in that, The n is 3 or 4, and the M1-M2-MXene is an iron / vanadium diatomic catalyst.

4. A method for preparing an iron / vanadium diatomic catalyst, characterized in that, The method includes: Step 1, Ti3C2T x MXene was dispersed in ultrapure water to obtain mixture I; Step 2: Add FeCl3·6H2O and NH4VO3 to the mixture I and stir until homogeneous to obtain mixture II; Step 3: Filter and dry the mixture II to obtain solid powder I; Step 4: Place the solid powder I in a tube furnace and calcine it at high temperature under a protective atmosphere to obtain solid powder II; Step 5: The solid powder II is acid-washed and water-washed several times until the solution pH > 6.5, filtered, and dried to obtain iron / vanadium diatomic catalyst powder.

5. The method for preparing the iron / vanadium diatomic catalyst as described in claim 4, characterized in that, The FeCl3·6H2O and NH4VO3 are in a molar ratio of 1:(1~2).

6. The method for preparing the iron / vanadium diatomic catalyst as described in claim 4, characterized in that, In step 4, the high-temperature calcination temperature is 500℃~900℃, and the heating rate is 3-10℃·min. -1 .

7. An iron / vanadium diatomic catalyst, characterized in that, It is formed by supporting iron and vanadium in Ti3C2Tx MXene, wherein the molar ratio of iron to vanadium is 1:(1~2), and the molar ratio of Fe to Ti3C2Tx MXene is (0.25~1):

1.

8. The use of the iron / vanadium diatomic catalyst as described in claim 7, characterized in that, Used to treat bisphenol A in water bodies or to treat photovoltaic wastewater.

9. The use of the iron / vanadium diatomic catalyst as described in claim 8, characterized in that, A method for treating bisphenol A in water includes: adding the iron / alum diatomic catalyst to the water to be treated and mixing it, then adding potassium persulfate to adjust the pH of the water to 3-11 and the water temperature to 293-313 K; wherein the dosage of the iron / alum diatomic catalyst is 0.5-2.0 g / L.

10. The use of the iron / vanadium diatomic catalyst as described in claim 8, characterized in that, A method for treating photovoltaic wastewater includes: fixing the iron / vanadium diatomic catalyst in a filtration device, allowing photovoltaic wastewater mixed with potassium persulfate to pass through, and discharging treated water.

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