Fenton-like catalyst and preparation method thereof, Fenton-like catalytic system and wastewater treatment method

Abstract

The present invention relates to the field of water treatment technology, specifically to a Fenton-like catalyst and a preparation method thereof, a Fenton-like catalytic system and a wastewater treatment method. The present invention realizes an effective method for producing types of active species in a Fenton-like catalytic system by regulating the single-atom coordination environment, thereby synchronously regulating the catalytic activity and selectivity of the material. Experiments show that the Cu1-MgO-like Fenton catalyst and the Cu1@MgO-like Fenton catalyst provided by the embodiment of the present invention, due to the different coordination environments of Cu single atoms in MgO, the active species produced by the activated PMS are different types of high-valent metal Cu (III), and there are significant differences in the proportion of secondary active species and pollutant degradation characteristics: the Cu1@MgO catalytic system is more inclined to remove electron-deficient organics such as benzoic acid and nitrobenzene, while Cu1-MgO is more inclined to remove electron-rich organics such as phenol and 2-chlorophenol.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a Fenton-like catalyst and a preparation method thereof, a Fenton-like catalytic system and a wastewater treatment method. Background Art

[0002] Persulfate-based Fenton-like advanced oxidation technology can effectively remove non-biodegradable organic pollutants in water and can be used in water treatment and water environment remediation (Chemical Engineering Journal 2021, 410, 128312). This type of technology usually requires the use of a catalyst to activate PMS to produce sulfate radicals (SO4 ·- ), hydroxyl radicals ( · OH), superoxide radicals (O2 ·- ) and other active species, thereby achieving oxidative degradation of pollutants (Accounts of Chemical Research 2018, 51(3), 678-687). However, due to the short lifetime of free radicals and poor reaction selectivity, the removal efficiency of difficult-to-degrade pollutants is often low and secondary pollution is generated, which seriously limits the practical environmental application of such technologies.

[0003] In contrast, non-radical catalytic systems produce singlet oxygen ( 1O2), adsorbed intermediates of peroxymonosulfate (PMS*), and high-valent metals, and other active species have good selectivity for a variety of difficult-to-degrade pollutants. They can not only improve the efficiency of pollutant degradation but also reduce oxidant consumption, and have broad development and application prospects. In recent years, the selective and harmless degradation of various emerging pollutants has become an important development direction of current water treatment technology. The selective regulation of active species has become particularly important. The core lies in the development of highly selective catalysts to achieve precise regulation of the catalytic reaction pathway (Environmental Science & Technology 2022, 56(12), 8833-8843). Although researchers have made some progress in catalyst optimization construction and regulation methods, the existing optimization and regulation methods mainly focus on optimizing the composition structure of the catalyst material itself, and are mainly concentrated in the field of metal oxides / carbon nanomaterials (Accounts of Chemical Research 2018, 51(3), 678-687, Environmental Science & Technology 2022, 56(12), 8984-8992, Proceedings of the National Academy of Sciences 2022, 119(31)). Most catalysts find it difficult to have both high catalytic activity and selectivity.

[0004] In recent years, Fenton-like advanced oxidation technologies based on single-atom catalysts have developed rapidly due to their high reactivity and extremely low catalyst dosage (Chemical Society Reviews 2021, 50(8), 5281-5322). The existing common single-atom coordination regulation methods include: regulating the type of coordinating atoms and the number of atoms in the single-atom active sites, the interaction between heteroatoms introduced into the substrate and single atoms, the interaction between adjacent single-atom active sites, and changes in the spatial microenvironment (Nano-micro letters 2021, 13(1), 136). However, these methods generally have problems such as complex regulation means and poor stability, and it is difficult to achieve joint regulation of selectivity and catalytic activity. In summary, there is still a lack of a method for regulating the types of active species produced in single-atom Fenton-like catalytic systems that is simple to prepare, stable and controllable. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a Fenton-like catalyst and a preparation method thereof, a Fenton-like catalytic system and a wastewater treatment method. The catalyst provided by the present invention can regulate the types and proportions of active species in the Fenton-like catalytic system, thereby achieving efficient and selective degradation of different types of organic pollutants.

[0006] The present invention provides a Fenton-like catalyst comprising a first metal single atom and a second metal oxide;

[0007] The first metal single atom is doped in the crystal lattice of the second metal oxide;

[0008] The first metal and the second metal are different;

[0009] The first metal single atom is selected from transition metal single atoms.

[0010] The present invention dopes the first metal single atom into the crystal lattice of the second metal oxide, wherein the first metal single atom is specifically selected from at least one of Cu single atom, Fe single atom, Co single atom or Ni single atom, preferably selected from Cu single atom. The doping amount of the first metal single atom of the present invention is wt% to 10wt%, preferably 0.5wt%. The second metal oxide of the present invention is selected from at least one of MgO or Al2O3, preferably MgO. In one embodiment, the Fenton-like catalyst of the present invention comprises Cu single atoms and MgO; the Cu single atoms are doped in the crystal lattice of the MgO; the doping amount of the Cu single atoms is 0.25wt% to 10wt%, preferably 0.5wt%.

[0011] The present invention also provides a Fenton-like catalyst comprising a first metal single atom and a second metal oxide;

[0012] The metal single atom is supported on the surface of the metal oxide;

[0013] The first metal and the second metal are different;

[0014] The first metal single atom is selected from transition metal single atoms.

[0015] The present invention loads the first metal single atom on the surface of the second metal oxide, and the first metal single atom is specifically selected from at least one of Cu single atom, Fe single atom, Co single atom or Ni single atom, preferably selected from Cu single atom. The loading amount of the first metal single atom of the present invention is 0.25wt% to 10wt%, preferably 0.5wt%. The second metal oxide of the present invention is selected from at least one of MgO or Al2O3, preferably MgO. In one embodiment, the Fenton-like catalyst of the present invention includes Cu single atoms and MgO; the Cu single atoms are loaded on the surface of the MgO; the loading amount of the Cu single atoms is 0.25wt% to 10wt%, preferably 0.5wt%.

[0016] The Fenton-like catalyst provided by the present invention can regulate the types and proportions of active species in the Fenton-like catalytic system by regulating the doping position of the first metal single atom in the second metal oxide, thereby achieving efficient degradation of different types of organic pollutants; when the first metal single atom in the Fenton-like catalyst is doped in the lattice of the second metal oxide, the Fenton-like catalyst is more suitable for removing electron-deficient organic substances such as benzoic acid or nitrobenzene; when the first metal single atom in the Fenton-like catalyst is loaded on the surface of the second metal oxide, the Fenton-like catalyst is more suitable for removing electron-rich organic substances such as phenol and 2-chlorophenol.

[0017] The present invention also provides a method for preparing the aforementioned Fenton-like catalyst. Specifically, when a single atom of the first metal in the Fenton-like catalyst is doped into the crystal lattice of a second metal oxide, the method for preparing the Fenton-like catalyst comprises the following steps: calcining a co-precipitate of the first metal source and the second metal source to obtain the Fenton-like catalyst. In certain embodiments of the present invention, the first metal source, the second metal source, and a precipitant are mixed and heated to react to obtain a co-precipitate of the first metal source and the second metal source; and calcining the co-precipitate of the first metal source and the second metal source in air to obtain the Fenton-like catalyst.

[0018] The present invention first prepares a co-precipitate of a first metal source and a second metal source. Specifically, the present invention first mixes the first metal source, the second metal source, and a precipitant, and heats the mixture to react, thereby obtaining a co-precipitate of the first metal source and the second metal source. In certain embodiments of the present invention, the present invention first dissolves the first metal source and the second metal source in water to obtain an aqueous solution of the first metal source and the second metal source. The aqueous solution of the first metal source and the second metal source is then mixed with an aqueous solution of the precipitant, and heated to react, thereby obtaining a co-precipitate of the first metal source and the second metal source.

[0019] In one embodiment, the first metal source is selected from at least one of copper nitrate, iron nitrate, cobalt nitrate or nickel nitrate, preferably copper nitrate; the second metal source is selected from at least one of magnesium nitrate or aluminum nitrate, preferably magnesium nitrate; the precipitant is selected from at least one of Na2CO3 or sodium hydroxide, preferably Na2CO3. In one embodiment, the molar ratio of the first metal source, the second metal source and the precipitant is (0.00159-0.063):1:1. In one embodiment, the molar ratio of the copper nitrate, magnesium nitrate and sodium carbonate is (0.00159-0.063):1:1. In one embodiment, the temperature of the heating reaction is 60°C to 75°C, and the time of the heating reaction is 1h to 10h, preferably the temperature is 75°C and the time is 2h.

[0020] After obtaining a co-precipitate of a first metal source and a second metal source, the present invention calcines the co-precipitate of the first metal source and the second metal source to obtain the Fenton-like catalyst. Specifically, the present invention calcines the co-precipitate of the first metal source and the second metal source in air to obtain the Fenton-like catalyst. In one embodiment, the calcination temperature is 800°C to 850°C, preferably 850°C; the calcination time is 2 hours to 5 hours, preferably 5 hours; and the calcination heating rate is 2°C / min to 10°C / min, preferably 5°C / min.

[0021] The present invention also provides another method for preparing the aforementioned Fenton-like catalyst. Specifically, when the first metal atom in the Fenton-like catalyst is supported on the surface of the second metal oxide, the method for preparing the Fenton-like catalyst comprises the following steps: mixing the oxide of the second metal source with the first metal source and calcining the mixture to obtain the Fenton-like catalyst. In certain embodiments of the present invention, the second metal source and a precipitant are mixed and reacted, and the resulting reaction product is oxidized and calcined to obtain the oxide of the second metal source; and the oxide of the second metal source is mixed with the first metal source and calcined to obtain the Fenton-like catalyst.

[0022] The present invention first prepares an oxide of the second metal source. Specifically, the present invention first mixes the second metal source and a precipitant for reaction, and then oxidizes and calcines the resulting product to obtain the oxide of the second metal source. In certain embodiments of the present invention, the present invention dissolves the second metal source in water to obtain an aqueous solution of the second metal source, mixes the aqueous solution of the second metal source with an aqueous solution of the precipitant for reaction, and then oxidizes and calcines the resulting product to obtain the oxide of the second metal source.

[0023] In one embodiment, the second metal source is selected from at least one of magnesium nitrate or aluminum nitrate, preferably magnesium nitrate; the precipitant is selected from at least one of Na2CO3 or sodium hydroxide, preferably Na2CO3. In one embodiment, the molar ratio of the second metal source and the precipitant is 1:1. In one embodiment, the temperature of the mixed reaction is 60°C to 75°C, and the time of the mixed reaction is 1h to 10h, preferably the temperature is 75°C and the time is 2h. In one embodiment, the temperature of the oxidative calcination is 800°C to 850°C, preferably the temperature is 850°C; the time of the oxidative calcination is 2h to 5h, preferably 5h; the heating rate of the oxidative calcination is 2°C / min to 10°C / min, preferably the heating rate is 5°C / min.

[0024] After obtaining the oxide of the second metal source, the present invention mixes the oxide of the second metal source with the first metal source and calcines them to obtain the Fenton-like catalyst. Specifically, the oxide of the second metal source is mixed with the first metal source and calcined in air to obtain the Fenton-like catalyst. In one embodiment, the first metal source is selected from at least one of copper nitrate, iron nitrate, cobalt nitrate, and nickel nitrate, preferably copper nitrate. In one embodiment, the molar ratio of the oxide of the second metal source to the first metal source is 1:(0.00159-0.063). In one embodiment, the molar ratio of the magnesium nitrate to copper nitrate is 1:(0.00159-0.063). In one embodiment, the calcination temperature is 500°C to 550°C, preferably 550°C; the calcination time is 2 hours to 5 hours, with the time being 2 hours; and the calcination heating rate is 2°C / min to 10°C / min, with the heating rate being 5°C / min.

[0025] The present invention also provides a Fenton-like catalytic system comprising a catalyst and a persulfate; the catalyst is the aforementioned Fenton-like catalyst or a Fenton-like catalyst prepared by the aforementioned preparation method. The present invention has no particular limitations on the persulfate; it may be any persulfate well known to those skilled in the art that can constitute a Fenton-like catalytic system, such as at least one of peroxymonosulfate (PMS) and peroxydisulfate (PDS). In one embodiment, the mass ratio of the catalyst to the persulfate is (0.05-0.4):(0.1-0.4).

[0026] The present invention also provides a wastewater treatment method, using the above-mentioned Fenton-like catalytic system to treat wastewater. Specifically, the above-mentioned Fenton-like catalytic system is mixed with wastewater to treat the wastewater. In certain embodiments of the present invention, the above-mentioned Fenton-like catalyst and wastewater are mixed, stirred for 15 to 60 minutes to reach adsorption equilibrium, and then the above-mentioned persulfate is added to treat the wastewater; preferably, the above-mentioned Fenton-like catalyst and wastewater are mixed, stirred for 30 minutes to reach adsorption equilibrium, and then the above-mentioned persulfate is added to treat the wastewater. In one embodiment, the concentration of the Fenton-like catalyst in the wastewater is 0.05 g / L to 0.4 g / L, and the concentration of the persulfate in the wastewater is 0.1 g / L to 0.4 g / L. The wastewater of the present invention includes at least one organic pollutant selected from the group consisting of phenol, 2-chlorophenol, benzoic acid, and nitrobenzene. The initial concentration of the organic pollutants in the wastewater of the present invention is 0.05 mmol / L to 0.2 mmol / L. In certain embodiments of the present invention, the present invention terminates the wastewater treatment process of the above-mentioned Fenton-like catalytic system by adding Na2SO3 to the wastewater.

[0027] The present invention provides a Fenton-like catalyst and a preparation method thereof, a Fenton-like catalytic system and a wastewater treatment method. Different from the existing common single-atom coordination regulation method, the present invention intends to realize an effective method for regulating the types of active species in the Fenton-like catalytic system by regulating the single-atom coordination environment, thereby simultaneously regulating the catalytic activity and selectivity of the material. The Fenton-like catalyst of the present invention is based on low-cost metal oxides (such as magnesium oxide), and has the advantages of flexible and adjustable structure, green and cheap raw materials, simple preparation method, and suitability for large-scale production applications. The catalyst can achieve efficient and selective degradation of a variety of organic pollutants. For example, the Cu1-MgO Fenton-like catalyst provided in the embodiment of the present invention can remove 98% of phenol within 3 minutes, and exhibits good pollutant removal effects in a wide pH range (pH = 3 to 10) and in the presence of a variety of interfering ions, effectively overcoming the shortcomings of traditional Fenton-like catalysts such as complicated preparation, low catalytic efficiency, and severe environmental interference.

[0028] The present invention achieves effective regulation of Fenton-like catalytic pathways and the types of active species produced by optimizing and designing the unique coordination environment of metal single atoms in the oxide substrate. Specifically, the present invention utilizes the diversity and flexible adjustability of the composition and structure of bimetallic oxide materials, optimizes the unique coordination environment of metal single atoms by changing the embedding depth of metal single atoms in the oxide substrate, and respectively embeds another metal atom into the lattice of the metal substrate or loads it on the surface, thereby preparing two groups of Cu / MgO single-atom nanomaterials with unique composition structures, achieving simultaneous regulation of catalytic activity and selectivity.

[0029] Experiments show that the Cu1-MgO-type Fenton catalyst and the Cu1@MgO-type Fenton catalyst provided by the embodiment of the present invention have different coordination environments of Cu single atoms in MgO, resulting in different types of high-valent metal Cu (III) active species generated by the activated PMS. There are significant differences in the proportion of secondary active species and pollutant degradation characteristics: the Cu1@MgO catalytic system is more inclined to remove electron-deficient organics such as benzoic acid and nitrobenzene, while Cu1-MgO is more inclined to remove electron-rich organics such as phenol and 2-chlorophenol. The experiment also shows that the two catalysts of the present invention have good chemical stability. After being reused 4 times in the activated PMS to degrade phenol, they still maintain more than 80% of their activity. The Cu ion dissolution is only 6-8ug / L, and the catalytic performance can be fully restored by heat treatment, indicating that the material has good reusability and huge environmental application potential. Not only that, the regulation method provided by the present invention is also applicable to Fenton-type catalytic systems of other types of metal single atoms (such as Fe, Co, Ni). The research results of the present invention confirm that the types of active species produced and the organic matter degradation mechanism in the metal single-atom Fenton catalytic system are determined by the single-atom coordination environment, which can provide theoretical and technical references for achieving water environment treatment of specific pollution types. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the XRD pattern of the Cu1@MgO material obtained in Example 1;

[0031] Figure 2 The XRD pattern of the Cu1-MgO material obtained in Example 1;

[0032] Figure 3 This is the SEM image of the Cu1@MgO material obtained in Example 1;

[0033] Figure 4 AC-HAADF-STEM image of the Cu1@MgO material obtained in Example 1;

[0034] Figure 5 This is the SEM image of the Cu1-MgO material obtained in Example 1;

[0035] Figure 6 AC-HAADF-STEM image of the Cu1-MgO material obtained in Example 1;

[0036] Figure 7 The cyclic test diagram of the Cu1@MgO catalyst for the degradation of phenol by activated PMS;

[0037] Figure 8 This is a cyclic test diagram of the performance of Cu1-MgO catalyst in activating PMS to degrade phenol;

[0038] Figure 9 Performance test diagram of Cu1@MgO and Cu1-MgO in degrading different pollutants;

[0039] Figure 10 This is the phenol degradation performance diagram of Cu1@MgO in systems with different pH values;

[0040] Figure 11 This is the phenol degradation performance diagram of Cu1@MgO in the presence of different anions;

[0041] Figure 12 This is the phenol degradation performance diagram of Cu1-MgO in systems with different pH values;

[0042] Figure 13 This is the phenol degradation performance diagram of Cu1-MgO in the presence of different anions;

[0043] Figure 14 The kinetic k value diagram of phenol degradation by activation of PMS by SA@MgO and SA-MgO (SA = Fe, Co, Ni) materials;

[0044] Figure 15 This is the kinetic k value diagram of the degradation of benzoic acid by activating PMS using SA@MgO and SA-MgO (SA = Fe, Co, Ni) materials. DETAILED DESCRIPTION

[0045] The present invention discloses a Fenton-like catalyst and a preparation method thereof, a Fenton-like catalyst and a wastewater treatment method. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters for implementation. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0046] The present invention will be further described below with reference to the embodiments:

[0047] Example 1

[0048] Preparation of single-atom catalyst Cu1@MgO: 3.85 g of Mg(NO3)2·6H2O and 11 mg of Cu(NO3)2·3H2O were dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, stirred at 75°C for 2 h, and then calcined in air at 850°C for 5 h with a heating rate of 5°C / min to obtain single-atom catalyst Cu1@MgO.

[0049] Preparation of the single-atom catalyst Cu1-MgO: 3.85 g of Mg(NO3)2·6H2O was dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, and stirred at 75°C for 2 h. The solution was then calcined in air at 850°C for 5 h at a heating rate of 5°C / min to obtain MgO powder. The resulting MgO powder was ultrasonically dispersed in deionized water, and 11 mg of Cu(NO3)2·3H2O was added. The solution was impregnated at room temperature for 6 h, and then calcined in air at 550°C for 2 h at a heating rate of 5°C / min to obtain the single-atom catalyst Cu1-MgO.

[0050] The material properties of the synthesized single-atom catalyst Cu1@MgO and single-atom catalyst Cu1-MgO were characterized and analyzed:

[0051] (1) Characterization of material morphology and structure: The Cu1@MgO and Cu1-MgO materials synthesized above were ground uniformly and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and spherical aberration corrected high-angle annular dark field scanning transmission microscopy (AC-HAADF-STEM).

[0052] Figure 1 This is the XRD pattern of the Cu1@MgO material obtained in Example 1; Figure 2 is the XRD pattern of the Cu1-MgO material obtained in Example 1; Figure 1 and Figure 2 It can be seen that compared with the standard card, the XRD diffraction spectra of Cu1@MgO and Cu1-MgO materials correspond to the characteristic peaks of the MgO phase and there are no other impurity peaks, indicating that there is no CuO and the doping of Cu single atoms does not change the MgO substrate phase; XRD refinement data show that in the Cu1@MgO material, the Cu ion radius is larger than that of Mg, and the embedding in the crystal lattice squeezes the Mg-O bond, resulting in a shorter bond length, and the Cu single atoms are successfully embedded in the MgO substrate lattice; in the Cu1-MgO material, the Cu single atoms are attached to the surface of the MgO substrate.

[0053] Figure 3 This is the SEM image of the Cu1@MgO material obtained in Example 1. Figure 4 This is the AC-HAADF-STEM image of the Cu1@MgO material obtained in Example 1. Figure 5 This is the SEM image of the Cu1-MgO material obtained in Example 1. Figure 6 AC-HAADF-STEM image of the Cu1-MgO material obtained in Example 1. Figures 3 to 6 It can be seen that SEM and AC-HAADF-STEM show that both catalysts have flower-like nanosheet structures with an average diameter of 2 to 3 μm, and the Cu single atoms are evenly dispersed without clusters.

[0054] (2) Material Chemical Composition Analysis: The synthesized Cu1@MgO and Cu1-MgO materials were thoroughly dissolved in nitric acid and then analyzed by inductively coupled atomic emission spectroscopy (ICP-AES). The test results showed that the Cu mass fraction in Cu1@MgO was 0.498 wt%; the Cu mass fraction in Cu1-MgO was 0.485 wt%. The results showed that the Cu mass fractions in the two materials were the same, and the number of active sites did not affect the reaction rate and selectivity of the system.

[0055] The performance and mechanism of phenol degradation by activating PMS were tested on the single-atom catalyst Cu1@MgO and single-atom catalyst Cu1-MgO materials synthesized above:

[0056] (1) Degradation of phenol (PhOH): 4 mg of the Cu1@MgO and Cu1-MgO catalysts synthesized above were ultrasonically dispersed in 20 mL of 0.2 mmol / L phenol solution, stirred for 30 min to reach adsorption equilibrium, and then 0.3 g / L PMS was added to start the reaction. During the reaction, a fixed amount of sample was added to a Na2SO3 solution to terminate the reaction, and the phenol concentration was tested using high performance liquid chromatography. The Cu1-MgO with better performance achieved a phenol removal rate of 98% within 3 min, and the Cu1@MgO could also achieve a phenol removal rate of 97% within 8 min. After 10 min of reaction, the catalyst was collected by centrifugation, washed with deionized water, and the above steps were repeated. A total of 4 cycles were tested, and the reaction time for each cycle was 10 min. The material collected after the fourth cycle was dried and calcined at 300 ° C for 1 h, and the above experiment was repeated. Figures 7-8 As shown, Figure 7 This is a cyclic test diagram of the performance of Cu1@MgO catalyst in activating PMS to degrade phenol. Figure 8 This is a cyclic test diagram of the performance of Cu1-MgO catalyst in activating PMS to degrade phenol; Figures 7-8 It can be seen that the performance of both Cu1@MgO and Cu1-MgO catalysts decreased slightly after four cycles, but the residual surface pollutant intermediates could be removed by calcination, restoring the catalytic performance. Therefore, the catalysts showed excellent catalytic performance and cyclic stability in activating PMS to degrade organic pollutants. Figures 7-8 The specific data are shown in Table 1, where Figures 7-8 The removal rate unit of the vertical axis is C / C0, where C is the pollutant concentration of the test system at a certain time, and C0 is the initial concentration of the pollutant in the test system. For a more intuitive representation, the removal rates in Table 1 are converted to removal rate percentages, and the calculation formula is % = 100% × (1-C / C0):

[0057] Table 1

[0058]

[0059] (2) Analysis of the catalytic reaction pathway: Ethanol and furfuryl alcohol were added to the reaction system as free radical scavengers, but the degradation of phenol was not completely inhibited. Electron paramagnetic resonance spectroscopy (EPR) results showed that there was no singlet oxygen in the system, but a small amount of hydroxyl radicals were present. At the same time, Raman spectroscopy detected a Cu(III)-OH signal, indicating that the system degraded organic matter using a high-valent metal mechanism, with hydroxyl radicals as secondary active species.

[0060] Example 2

[0061] Performance test of single-atom catalyst Cu1@MgO and single-atom catalyst Cu1-MgO materials for catalytic degradation of different pollutants:

[0062] The single-atom catalyst Cu1@MgO and the single-atom catalyst Cu1-MgO material synthesized in Example 1 were used to degrade four organic pollutants, phenol, 2-chlorophenol, benzoic acid and nitrobenzene, respectively. The concentrations of the catalyst, PMS and organic pollutants were kept consistent with those in Example 1, i.e., 4 mg of the catalyst was dispersed in 20 mL of 0.2 mmol / L organic pollutants, and the concentration of PMS was 0.3 g / L. Figure 9 As shown, Figure 9 The performance test diagram of Cu1@MgO and Cu1-MgO in degrading different pollutants; Figure 9 It can be seen that the degradation efficiency of the two materials for different pollutants is significantly different. Cu1@MgO is more inclined to remove electron-deficient organic compounds such as benzoic acid and benzoic acid. In contrast, Cu1-MgO is more inclined to remove electron-rich organic compounds such as phenol and 2-chlorophenol. Figure 9 The specific data are shown in Table 2:

[0063] Table 2

[0064]

[0065] Example 3

[0066] Cu1@MgO and Cu1-MgO materials are used for efficient degradation and removal of phenol in different water environments.

[0067] The single-atom Cu1@MgO and Cu1-MgO materials synthesized in Example 1 were heated at different pH values (3-10) and different anions (Cl-, SO4 2- , CO3 2- ,HCO3 - ) was used to test the performance of phenol degradation in a system in which phenol was present to evaluate the environmental tolerance of the system, wherein the concentrations of the catalyst, PMS, and phenol were kept consistent with those in Example 1, i.e., 4 mg of the catalyst was dispersed in 20 mL of 0.2 mmol / L phenol, and the concentration of PMS was 0.3 g / L.

[0068] like Figures 10-13 As shown, Figure 10 The phenol degradation performance diagram of Cu1@MgO in systems with different pH values is shown in the figure. Figure 11 The phenol degradation performance diagram of Cu1@MgO in the presence of different anions is shown in Figure 2. Figure 12 The phenol degradation performance diagram of Cu1-MgO in the system with different pH values is shown in the figure. Figure 13 The figure shows the phenol degradation performance of Cu1-MgO in the presence of different anions. Figures 10-13It can be seen that the system shows good removal effect on phenol under different water quality conditions. The system can efficiently degrade phenol within 10 minutes under different pH conditions and the presence of various interfering ions, and has good environmental tolerance, which proves that the system has good environmental applicability and application prospects in water treatment. Figures 10-13 The specific data are shown in Tables 3 to 6, where Figures 10-13 The removal rate unit of the vertical axis is C / C0, where C is the pollutant concentration of the test system at a certain time, and C0 is the initial concentration of the pollutant in the test system. For a more intuitive representation, the removal rates in Tables 3 to 6 are converted to removal rate percentages, and the calculation formula is % = 100% × (1-C / C0):

[0069] Table 3 Phenol degradation performance of Cu1@MgO in systems with different pH values

[0070]

[0071] Table 4 Phenol degradation performance of Cu1@MgO in the presence of different anions

[0072]

[0073] Table 5 Phenol degradation performance of Cu1-MgO in systems with different pH values

[0074]

[0075] Table 6 Phenol degradation performance of Cu1-MgO in the presence of different anions

[0076]

[0077] Example 4

[0078] Preparation of single-atom catalyst Fe@MgO: 3.85 g of Mg(NO3)2·6H2O and 15 mg of Fe(NO3)3·9H2O were dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, stirred at 75°C for 2 h, and then calcined in air at 850°C for 5 h with a heating rate of 5°C / min to obtain single-atom catalyst Fe1@MgO.

[0079] Preparation of the single-atom catalyst Fe1-MgO: 3.85 g of Mg(NO3)2·6H2O was dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, and stirred at 75°C for 2 h. The solution was then calcined in air at 850°C for 5 h at a heating rate of 5°C / min to obtain MgO powder. The resulting MgO powder was ultrasonically dispersed in deionized water, and 15 mg of Fe(NO3)3·9H2O was added. The solution was impregnated at room temperature for 6 h, and then calcined in air at 550°C for 2 h at a heating rate of 5°C / min to obtain the single-atom catalyst Fe1-MgO.

[0080] Preparation of single-atom catalyst Co@MgO: 3.85 g of Mg(NO3)2·6H2O and 12 mg of Co(NO3)2·6H2O were dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, stirred at 75°C for 2 h, and then calcined in air at 850°C for 5 h with a heating rate of 5°C / min to obtain single-atom catalyst Co1@MgO.

[0081] Preparation of the single-atom catalyst Co1-MgO: 3.85 g of Mg(NO3)2·6H2O was dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, and stirred at 75°C for 2 h. The solution was then calcined in air at 850°C for 5 h at a heating rate of 5°C / min to obtain MgO powder. The resulting MgO powder was ultrasonically dispersed in deionized water, and 12 mg of Co(NO3)2·6H2O was added. The solution was impregnated at room temperature for 6 h, and then calcined in air at 550°C for 2 h at a heating rate of 5°C / min to obtain the single-atom catalyst Co1-MgO.

[0082] Preparation of single-atom catalyst Ni@MgO: 3.85 g of Mg(NO3)2·6H2O and 12 mg of Ni(NO3)2·6H2O were dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, stirred at 75°C for 2 h, and then calcined in air at 850°C for 5 h with a heating rate of 5°C / min to obtain single-atom catalyst Ni1@MgO.

[0083] Preparation of the single-atom catalyst Ni1-MgO: 3.85 g of Mg(NO3)2·6H2O was dissolved in deionized water, mixed with an aqueous solution containing 1.59 g of Na2CO3 using a peristaltic pump, and stirred at 75°C for 2 h. The solution was then calcined in air at 850°C for 5 h at a heating rate of 5°C / min to obtain MgO powder. The resulting MgO powder was ultrasonically dispersed in deionized water, and 12 mg of Ni(NO3)2·6H2O was added. The solution was impregnated at room temperature for 6 h, and then calcined in air at 550°C for 2 h at a heating rate of 5°C / min to obtain the single-atom catalyst Ni1-MgO.

[0084] The single-atom catalysts SA@MgO and SA-MgO (SA = Fe, Co, Ni) prepared above were tested for degradation of different pollutants, and the test conditions were consistent with those in Example 2. The test results are shown in Figure 2. Figures 14-15 As shown, Figure 14 The kinetic k value diagram of SA@MgO and SA-MgO (SA = Fe, Co, Ni) materials activating PMS to degrade phenol. Figure 15 The kinetic k value diagram of SA@MgO and SA-MgO (SA = Fe, Co, Ni) materials activating PMS to degrade benzoic acid. Figures 14-15 It can be seen that the control method of the present invention is also applicable to Fenton-like catalytic systems based on single metal atoms such as Fe, Co, and Ni. Figures 14-15 The specific data are shown in Table 7:

[0085] Table 7

[0086]

[0087] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A Fenton-like catalyst, characterized in that including a first metal single atom and a second metal oxide; The first metal single atom is doped in the crystal lattice of the second metal oxide; The first metal and the second metal are different; The first metal single atom is selected from at least one of a Cu single atom, a Fe single atom, a Co single atom or a Ni single atom; The second metal oxide is selected from MgO; The loading amount of the first metal single atom is 0.25 wt% to 0.5 wt%.

2. A Fenton-like catalyst, characterized in that including a first metal single atom and a second metal oxide; The first metal single atom is supported on the surface of the second metal oxide; The first metal and the second metal are different; The first metal single atom is selected from at least one of a Cu single atom, a Fe single atom, a Co single atom or a Ni single atom; The second metal oxide is selected from MgO; The loading amount of the first metal single atom is 0.25 wt% to 0.5 wt%.

3. The method for preparing the Fenton-like catalyst according to claim 1, wherein The following steps are involved: calcining the co-precipitate of the first metal source and the second metal source to obtain the Fenton-like catalyst; The first metal source is selected from a Cu source, an Fe source, a Co source or a Ni source.

4. The method for preparing the Fenton-like catalyst according to claim 2, wherein The following steps are involved: mixing the oxide of the second metal source and the first metal source, and calcining the mixture to obtain the Fenton-like catalyst; The first metal source is selected from a Cu source, an Fe source, a Co source or a Ni source.

5. A Fenton-like catalytic system, characterized in that: including a catalyst and a persulfate; The catalyst is a Fenton-like catalyst as described in any one of claims 1 to 2 or a Fenton-like catalyst prepared by the preparation method as described in any one of claims 3 to 4.

6. The Fenton-like catalytic system according to claim 5, characterized in that: The mass ratio of the catalyst to the persulfate is (0.05-0.4):(0.1-0.4).

7. A wastewater treatment method, characterized in that: The wastewater is treated using the Fenton-like catalytic system described in claim 6.

Images