Water treatment method based on non-radical synergistic oxidation

Abstract

The application discloses a water treatment method based on non-radical synergistic oxidation, which comprises the following steps: adding Mn-C-N catalyst and persulfate into water, and utilizing the Mn-C-N catalyst to catalyze the decomposition of the persulfate to form singlet oxygen and electron transfer, and then performing non-radical synergistic oxidation purification treatment on pollutants in the water; and the preparation method of the Mn-C-N catalyst comprises the following steps: adding sodium alginate solution into calcium chloride solution, screening, and obtaining calcium alginate hydrogel, and then obtaining Mn-based precursor through ion exchange; mixing the Mn-based precursor with urea, and then sequentially performing nitrogen atmosphere calcination, acid pickling to remove surface Mn ions, water washing to neutral, and drying, so as to obtain the Mn-C-N catalyst. The Mn-C-N catalyst preparation method is simple, the Mn-C-N catalyst has two active sites which can respectively generate singlet oxygen and electron transfer two non-radical active species, and can synergistically accelerate the degradation and mineralization of organic pollutant wastewater.

Description

Technical Field

[0001] This invention relates to the field of water catalytic oxidation treatment technology, and more specifically to a water treatment method based on non-radical synergistic oxidation. Background Technology

[0002] Refractory organic pollutants have garnered significant attention over the past few decades due to their potential adverse effects on human and wildlife health. Ring-opening and mineralization of these pollutants via peroxides have become a commonly used remediation strategy. In recent years, persulfate-based advanced oxidation technologies have demonstrated great potential for removing recalcitrant organic pollutants. This is primarily due to the activation of persulfate (PMS) under the influence of catalysts or external energy, generating reactive species with high redox potentials, namely hydroxyl radicals (·OH, E₂). 0 =1.9~2.7V NHE ) and sulfate radicals (SO4) ·- E0 = 2.6~3.1V NHE While free radicals can efficiently mineralize pollutants into CO2 and H2O, they are easily annihilated by solute components, inorganic ions, and even pH fluctuations, thus increasing the ineffective consumption of oxidants. Therefore, there is an urgent need to improve the effective utilization efficiency of PMS, thereby reducing operating costs and enhancing the sustainability of wastewater remediation processes.

[0003] Besides free radical mechanisms, PMS also utilizes non-free radicals as the primary degradation mechanism in heterogeneous catalytic degradation of pollutants, including electron transfer processes (ETP) and singlet oxygen (SO2). 1 O2) and high-valence metal oxides. The aforementioned non-radical oxidation processes have been observed on various catalysts, including single-atom catalysts, nano-carbon materials, and metal oxides. Compared to free radicals, non-radicals exhibit higher catalytic efficiency and stronger selectivity in complex aqueous matrices and for electron-rich organic pollutants, effectively addressing the ineffective consumption of active species by interfering substances. These properties reduce PMS consumption in non-radical oxidation processes. From this perspective, non-radical oxidation provides a promising direction for promoting the sustainability of advanced oxidation technologies that heavily rely on chemicals. However, due to the low redox potential of non-radical species such as those undergoing electron transfer, their mineralization ability for pollutants is poor. Therefore, improving the treatment efficiency of non-radical oxidation processes is of great significance for their application in the treatment of recalcitrant wastewater.

[0004] During pollutant degradation, various intermediates with different structural properties are generated. Therefore, we reasonably hypothesize that more efficient and rapid pollutant removal performance can be achieved by synergistically coupling different non-free mechanisms within a single catalytic system. Although carbon catalysts and MnO have been previously reported... xDifferent non-radical activation mechanisms exist on catalysts, but these mechanisms suffer from unsatisfactory processing performance. Therefore, it is essential to appropriately design two independent active sites on a catalyst and adjust their exposure levels to achieve a rate trade-off that does not involve non-radical pathways.

[0005] Carbon materials have attracted widespread attention from researchers due to their large specific surface area, abundant reserves, and resistance to acids and alkalis. In recent years, it has been confirmed that carbon materials can activate persulfate to produce active substances that rapidly degrade pollutants. For example, reduced graphene oxide can activate polymethyl methacrylate (PMS) and degrade phenols and organic dyes; carbon nanotubes can activate PMS to produce… 1 O2 and SO4 ·- This process degrades benzyl alcohol. More importantly, using carbon catalysts in wastewater remediation can overcome narrow pH range limitations. Sodium alginate, an organic cross-linking agent, is a natural polysaccharide that is abundant and non-toxic. It contains numerous "egg-box" structures that can accommodate metal ions by coordinating with negatively charged gluconates. By altering the metal salt solution, the type and quantity of metal ions immobilized on the "egg-boxes" can be adjusted to achieve the desired effect. Summary of the Invention

[0006] To address the aforementioned technical problems and shortcomings in this field, the present invention provides a water treatment method based on non-radical synergistic oxidation, using a Mn-CN catalyst prepared by a specific method. This catalyst possesses two active sites with different functions, wherein the active site CN can efficiently catalyze the decomposition of persulfate to form singlet oxygen. 1 O2), the active site Mn-N can efficiently catalyze the decomposition of persulfate to form electron transfer (ETP). The synergistic effect of these two can achieve non-radical synergistic oxidation purification of pollutants in water (such as organic pollutants such as diclofenac), and accelerate the degradation and mineralization of organic pollutants.

[0007] The specific technical solution is as follows:

[0008] A water treatment method based on non-radical synergistic oxidation involves adding a Mn-CN catalyst and persulfate to water. The Mn-CN catalyst catalyzes the decomposition of persulfate to form singlet oxygen and electron transfer, thereby purifying pollutants in the water through non-radical synergistic oxidation. For example, the persulfate may be a potassium peroxymonosulfate complex salt (2KHSO5·KHSO4·K2SO4).

[0009] The preparation method of the Mn-CN catalyst includes the following steps:

[0010] (1) Sodium alginate solution was added dropwise to calcium chloride solution, sieved, and calcium alginate hydrogel was obtained. Then, it was immersed in hydrochloric acid and sonicated to complete the Ca... 2+ With H + After ion exchange and sieving, the resulting hydrogel is then added to a MnCl2 solution for impregnation with H2O. + With Mn 2+ Ion exchange, filtration and drying yielded the Mn-based precursor;

[0011] (2) The Mn-based precursor is mixed with urea, and then calcined in a nitrogen atmosphere, acid washed to remove surface Mn ions, washed with water until neutral, and dried to obtain the Mn-CN catalyst.

[0012] The inventors discovered that if urea is not added in step (2), i.e., only the Mn-based precursor is sequentially calcined under nitrogen atmosphere, acid-washed to remove surface Mn ions, washed with water until neutral, and dried, the resulting Mn-C catalyst used in water treatment for catalyzing the decomposition of persulfate mainly forms singlet oxygen, with the corresponding active sites being oxygen-containing functional groups, and its catalytic effect on persulfate decomposition is not as good as that of the Mn-CN catalyst. The inventors further conducted an oxygen-containing functional group masking experiment on the Mn-CN catalyst and found that when the oxygen-containing functional groups of the Mn-CN catalyst were masked, the Mn-CN catalyst still exhibited activity, indicating that oxygen-containing functional groups are not the main active sites of the Mn-CN catalyst.

[0013] In one embodiment, in step (1), the mass concentration of the sodium alginate solution is 0.8% to 1.2%.

[0014] In one embodiment, in step (1), the mass concentration of the calcium chloride solution is 0.4% to 0.6%.

[0015] In one embodiment, in step (1), the volume ratio of the sodium alginate solution to the calcium chloride solution is 0.2 to 0.3:1.

[0016] In one embodiment, in step (1), the concentration of the hydrochloric acid is 0.8 to 1.2 M.

[0017] In one embodiment, in step (1), the amount of hydrochloric acid used is excessive, so that all Ca in the calcium alginate hydrogel is dissolved. 2+ All were exchanged for H by ions + .

[0018] Mn 2+ Immobilization with hydrogels is achieved through ion exchange.

[0019] In one embodiment, in step (1), the concentration of the MnCl2 solution is 0.08 to 0.12 M. If the MnCl2 concentration is too high, the form in which Mn species exist in the catalyst may change, which in turn leads to changes in the active sites, ultimately resulting in a decrease in catalyst activity and a deterioration in catalytic performance; if the MnCl2 concentration is too low, the catalyst performance is poor.

[0020] In one embodiment, in step (1), the amount of MnCl2 solution used is excess, so that all H+ in the hydrogel is absorbed. + All were ion-exchanged into Mn 2+ .

[0021] In one embodiment, in step (2), the mass ratio of the Mn-based precursor to the urea is 3 to 5:1. This mass ratio range can ensure that an appropriate amount of N element is doped into the catalyst to obtain a catalyst with optimal performance.

[0022] Nitrogen atmosphere calcination mainly carbonizes Mn-based precursors, forming porous carbon with abundant pores, and anchoring Mn metal atoms to the carbon framework.

[0023] In one embodiment, in step (2), the calcination temperature in the nitrogen atmosphere is 780–820°C.

[0024] In one embodiment, in step (2), the calcination time in the nitrogen atmosphere is 1.5 to 2.5 hours.

[0025] In one embodiment, in step (2), the acid used for pickling is 1 mol·L⁻¹. -1 The hydrochloric acid was used, and the pickling was performed three times.

[0026] In one embodiment, in step (2), the drying temperature is 60-70°C.

[0027] In one embodiment, the water treatment method based on non-radical synergistic oxidation, wherein the persulfate is a potassium peroxymonosulfate complex salt 2KHSO5·KHSO4·K2SO4, and the pollutant in the water is diclofenac.

[0028] As a general inventive concept, this invention also provides the application of the Mn-CN catalyst in catalyzing the decomposition of persulfates (such as potassium peroxymonosulfate complex salt (2KHSO5·KHSO4·K2SO4) etc.) to form singlet oxygen and electron transfer for non-radical synergistic oxidation purification of pollutants in water.

[0029] In the aforementioned applications, the preparation method of the Mn-CN catalyst and the specific selection of related technical solutions can refer to the water treatment method based on non-radical synergistic oxidation described above.

[0030] In one embodiment, the persulfate is a potassium peroxymonosulfate complex salt 2KHSO5·KHSO4·K2SO4, and the pollutant in the water is diclofenac.

[0031] The present invention can identify and characterize the non-radical types of persulfate decomposition catalyzed by the Mn-CN catalyst by the following method: using the Mn-CN catalyst to activate persulfate, and confirming the formation of singlet oxygen and electron transfer through quenching experiments and constant potential time-current response experiments.

[0032] In one embodiment, the mass of the Mn-CN catalyst in the quenching experiment is 5–10 mg.

[0033] In one embodiment, the concentration of persulfate in the quenching experiment is 0.65 mM.

[0034] In one embodiment, the concentrations of ethanol and tert-butanol in the quenching experiment were independently 65–130 mM, respectively, verifying the absence of ·OH and SO42- in the Mn-CN / PMS system at high concentrations. ·- .

[0035] In one embodiment, the concentration of β-carotene in the quenching experiment was 0.185–0.370 mM, indicating the presence of β-carotene in the Mn-CN / PMS system. 1 O2.

[0036] In one embodiment, the mass of the Mn-CN catalyst in the constant potential time-current response experiment is 5-10 mg, and the resulting suspension can adhere to the working electrode.

[0037] In one embodiment, the concentration of persulfate in the constant potential time-current response experiment is 0.125 mM.

[0038] In one embodiment, the concentration of diclofenac in the constant potential time-current response experiment is 50 mg / L.

[0039] Compared with the prior art, the beneficial effects of this invention are as follows:

[0040] 1. Sodium alginate, an organic crosslinking agent, is impregnated in a metal salt solution. The unique internal structure of the crosslinking agent is used to anchor metal atoms and disperse active sites. Then, Mn-CN catalyst is prepared by ion exchange, which simplifies the operation steps.

[0041] 2. The preparation method of the Mn-CN catalyst of the present invention is simple. It has two active sites that can generate singlet oxygen and electron transfer, two non-radical active species, respectively, which can synergistically accelerate the degradation and mineralization of organic pollutant wastewater.

[0042] 3. The wastewater treatment method in this invention is low in cost, has no stringent requirements for experimental conditions, is suitable for application in the treatment of actual wastewater, and has excellent degradation performance. Attached Figure Description

[0043] Figure 1 The image shows a scanning electron microscope (SEM) image of the Mn-CN catalyst prepared in Example 1.

[0044] Figure 2 Here is a SEM image of the Mn-C catalyst prepared in Example 1;

[0045] Figure 3 The X-ray diffraction (XRD) patterns of the Mn-CN catalyst and the Mn-C catalyst prepared in Example 1 are shown.

[0046] Figure 4 The X-ray photoelectron spectroscopy (XPS) spectra of the Mn-CN catalyst prepared in Example 1 are shown in (a) as C1s spectrum of carbon, (b) as O1s spectrum of oxygen, (c) as N1s spectrum of nitrogen, and (d) as Mn 2p spectrum of manganese.

[0047] Figure 5 The images shown are EDS energy spectrum images of the Mn-CN catalyst prepared in Example 1, where (a) is a transmission electron microscope (TEM) image of the Mn-CN catalyst, (b) is the EDS energy spectrum of carbon, (c) is the EDS energy spectrum of nitrogen, and (d) is the EDS energy spectrum of manganese.

[0048] Figure 6 The figure shows the quenching experiment results of the Mn-CN catalyst in Example 2;

[0049] Figure 7 The potential-time-current response diagram of the Mn-CN catalyst in Example 3 is shown.

[0050] Figure 8 This is a graph showing the degradation curves of diclofenac in different water environments in Example 4;

[0051] Figure 9 The figure shows the degradation experiment results of Example 5. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0053] Example 1: Preparation of Mn-CN and Mn-C catalysts

[0054] 250 mL of a 1% (w / w) aqueous solution of sodium alginate, an organic crosslinking agent, was added dropwise to 1000 mL of a 0.5% (w / w) calcium chloride solution. The solution was sieved to obtain a calcium alginate hydrogel. This hydrogel was then immersed in 300 mL of 1 M hydrochloric acid and sonicated to complete the Ca2+ crosslinking process. 2+ With H + After ion exchange, the hydrogel was sieved and then added to 200 mL of 0.1 M MnCl2 solution for impregnation with H2O. + With Mn 2+ Ion exchange, filtration and drying yield Mn-based precursor.

[0055] 1.5 g of the above Mn-based precursor was mixed with 0.3 g of urea and calcined at 800 °C for 2 h under a nitrogen atmosphere. The calcined product was then subjected to 1 mol·L⁻¹ water treatment. -1 The surface Mn metal ions were removed by treating with hydrochloric acid three times, followed by washing with distilled water until the washing solution was neutral, and then dried in a vacuum drying oven at 70°C for 5 hours. The dried product was then thoroughly ground in an agate grinding mortar for 60 minutes to obtain the Mn-CN catalyst.

[0056] 1.5 g of the above Mn-based precursor was calcined at 800 °C for 2 h in a nitrogen atmosphere. The calcined product was then subjected to 1 mol·L⁻¹ water treatment. -1 The surface Mn metal ions were removed by treating with hydrochloric acid three times, followed by washing with distilled water until the washing solution was neutral, and then dried in a vacuum drying oven at 70°C for 5 hours. The dried product was then thoroughly ground in an agate grinding mortar for 60 minutes to obtain the Mn-C catalyst.

[0057] Figure 1 The image shows a SEM image of the Mn-CN catalyst described above. As can be seen from the image, the Mn-CN catalyst of the present invention is a material with abundant network pores.

[0058] Figure 2 The image shows a SEM image of the Mn-C catalyst. As can be seen from the image, due to the absence of urea doping, the porous structure of Mn-C is different from that of the Mn-CN catalyst.

[0059] Figure 3 The above are the XRD patterns of the Mn-CN catalyst and the Mn-C catalyst. As can be seen from the figure, there are obvious carbon-related peaks in both the Mn-CN catalyst and the Mn-C catalyst of the present invention. No other crystal phase peaks related to manganese were observed. This is probably because the size of the manganese-related species is too small and the dispersion is very high, making it difficult for the XRD detection to show the peaks.

[0060] Figure 4The above-mentioned Mn-CN catalyst's XPS spectra show that the C element XPS spectrum has a very strong peak, which is C=C (284.8 eV), representing graphitized carbon. The O element XPS spectrum can be divided into two peaks, corresponding to CO and C=O respectively. The N element N1s XPS spectrum can be fitted as a superposition of three peaks, corresponding to three different nitrogen atoms: pyridine N (398.5 eV), pyrrole N (399.8 eV), and graphitic N (400.8 eV). The Mn 2p XPS results show almost no Mn peaks. This is likely because the XPS test method itself can only detect the elemental composition at a depth of a few nanometers on the material surface. The Mn-CN catalyst of this invention has had its surface manganese metal ions removed by acid washing, making it difficult to detect by XPS.

[0061] Figure 5 The figure shows the EDS spectrum of the Mn-CN catalyst. As can be seen from the figure, C, N, and Mn are uniformly distributed on the Mn-CN catalyst, indicating that the Mn-CN catalyst was successfully prepared. The combination of EDS spectrum results with XPS and XRD test results shows that in the Mn-CN catalyst of this invention, Mn-related species are mainly distributed in the bulk catalyst phase and have a high degree of dispersion.

[0062] Example 2 Quenching experiment of Mn-CN catalyst

[0063] The Mn-CN catalyst (10 mg) prepared in Example 1 was added to three beakers containing 50 mL of 50 mg / L diclofenac solution and stirred for 20 min to ensure adsorption-desorption equilibrium. Then, 0.379 mL of ethanol, 0.621 mL of tert-butanol, and 1 mL of β-carotene solution were added to the three beakers respectively, so that the concentrations of ethanol and tert-butanol in their respective solutions were 130 mM, and the concentration of β-carotene solution was 0.37 mM. At the same time as adding the above three quenchers, 0.1 mL of PMS stock solution (i.e., 0.2 g / mL potassium peroxymonosulfate complex salt (2 KHSO5·KHSO4·K2SO4) solution) was added to each of the three beakers, so that the concentration of PMS in the solution was 0.65 mM. At certain time intervals, 0.5 mL of the reaction mixture solution was transferred to a centrifuge tube pre-filled with 0.1 mL of methanol, and then immediately centrifuged at 13000 rpm. After centrifugation, 200 μL of the supernatant was taken and the concentration of diclofenac was determined by high performance liquid chromatography.

[0064] Analysis results:

[0065] Figure 6The figure shows the quenching experiment results of the Mn-CN catalyst. As can be seen from the figure, the degradation curve of diclofenac did not change significantly after the addition of ethanol and tert-butanol to the Mn-CN / PMS system. However, the degradation of diclofenac was inhibited after the addition of β-carotene solution. Therefore, it can be concluded that ·OH and SO42- are absent in the Mn-CN / PMS system. ·- However, it exists. 1 O2.

[0066] Example 3: Potential-time-current response diagram of Mn-CN catalyst

[0067] A three-electrode system was assembled using Pt as the counter electrode, Ag / AgCl as the reference electrode, and a glassy carbon electrode as the working electrode. First, 5 mg of the Mn-CN catalyst prepared in Example 1 was added to 0.5 mL of 75 vol% isopropanol solution to prepare a catalyst suspension, which was then ultrasonically dispersed for 20 min. 10 μL of the suspension was dropped onto the surface of the working electrode and left to dry naturally for 30 min. The working electrode was then immersed in a 0.1 M sodium sulfate solution electrolyte for 30 min to ensure complete contact. Once the open-circuit voltage stabilized, the obtained open-circuit voltage was set as the potential of the constant-potential current response curve. Persulfate (specifically potassium peroxymonosulfate complex salt (2KHSO5·KHSO4·K2SO4)) solution and diclofenac were added to the system at 200 s and 400 s, respectively, with final concentrations of 0.125 mM and 25 mg / L. Current changes were recorded using time-current curves.

[0068] Analysis results:

[0069] Figure 7 The figure shows the galvanostatic time-current response of the Mn-CN catalyst. As can be seen, the addition of persulfate significantly increased the current density. Furthermore, by adding diclofenac to the electrolyte, a change in current density could be observed over a certain period. Therefore, it can be concluded that ETP exists in the Mn-CN / PMS system.

[0070] Example 4: Degradation curves of diclofenac under different water conditions

[0071] 50 mg of diclofenac was dissolved in 1 L of deionized water and river water (referred to as actual wastewater), respectively. Then, 10 mg of the Mn-CN catalyst prepared in Example 1 was added to each solution, and the mixture was stirred for 20 min to ensure adsorption-desorption equilibrium. Subsequently, 0.1 mL of PMS stock solution (i.e., a 0.2 g / mL solution of potassium persulfate complex salt (2KHSO5·KHSO4·K2SO4)) was added to initiate the catalytic degradation reaction. At certain time intervals, 0.5 mL of the reaction mixture was transferred to a centrifuge tube pre-filled with 0.1 mL of methanol and immediately centrifuged at 13000 rpm. After centrifugation, 200 μL of the supernatant was used to determine the concentration of diclofenac by high-performance liquid chromatography.

[0072] Analysis results:

[0073] Figure 8 This is a graph showing the degradation curves of diclofenac under different water environments in Example 4. As can be seen from the graph, the Mn-CN / PMS system can efficiently and rapidly degrade diclofenac in different water environments, with reaction rate constants of 0.26 min⁻¹. -1 and 0.18min -1 .

[0074] Example 5: Degradation experiment of diclofenac

[0075] The Mn-CN catalyst (10 mg) and Mn-C catalyst (10 mg) prepared in Example 1 were added to two beakers containing 50 mL of 50 mg / L diclofenac solution and stirred for 20 min to ensure adsorption-desorption equilibrium. After 20 min, another beaker containing 50 mL of 50 mg / L diclofenac solution was prepared, and 0.1 mL of PMS stock solution (i.e., 0.2 g / mL potassium persulfate complex salt (2KHSO5·KHSO4·K2SO4) solution) was added to each of the three beakers to make the PMS concentration in the solution 0.65 mM. At certain time intervals, 0.5 mL of the reaction mixture solution was transferred to a centrifuge tube pre-filled with 0.1 mL of methanol and immediately centrifuged at 13000 rpm. After centrifugation, 200 μL of the supernatant was taken and the concentration of diclofenac was determined by high performance liquid chromatography. Figure 9 This is a degradation curve of diclofenac. As shown in the graph, PMS alone cannot degrade diclofenac. However, after reacting for 15 minutes with persulfate solution, almost all diclofenac was degraded in the Mn-CN / persulfate system. In contrast, the Mn-C / persulfate system showed limited removal efficiency for diclofenac.

[0076] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A water treatment method based on non-radical synergistic oxidation, characterized in that, Mn-CN catalyst and persulfate are added to water. The Mn-CN catalyst catalyzes the decomposition of persulfate to form singlet oxygen and electron transfer, which is used to carry out non-radical synergistic oxidation purification of pollutants in the water. The preparation method of the Mn-CN catalyst includes the following steps: (1) Sodium alginate solution was added dropwise to calcium chloride solution, sieved, and calcium alginate hydrogel was obtained. Then it was immersed in hydrochloric acid and sonicated to complete the Ca2+ reaction. 2+ With H + After ion exchange and sieving, the resulting hydrogel is then added to a MnCl2 solution for impregnation with H2O. + With Mn 2+ Ion exchange, filtration, and drying yielded the Mn-based precursor; the concentration of the MnCl2 solution was 0.08–0.12 M. (2) The Mn-based precursor is mixed with urea, and then calcined in a nitrogen atmosphere, acid washed to remove surface Mn ions, washed with water until neutral, and dried to obtain the Mn-CN catalyst; the mass ratio of the Mn-based precursor to the urea is 3~5:

1.

2. The water treatment method based on non-radical synergistic oxidation according to claim 1, characterized in that, In step (1): The sodium alginate solution has a mass concentration of 0.8% to 1.2%. The mass concentration of the calcium chloride solution is 0.4%~0.6%; The volume ratio of the sodium alginate solution to the calcium chloride solution is 0.2~0.3:

1.

3. The water treatment method based on non-radical synergistic oxidation according to claim 1, characterized in that, In step (1): The concentration of the hydrochloric acid is 0.8~1.2 M.

4. The water treatment method based on non-radical synergistic oxidation according to claim 1, characterized in that, In step (2), the nitrogen atmosphere calcination temperature is 780~820℃ and the time is 1.5~2.5 h.

5. The water treatment method based on non-radical synergistic oxidation according to claim 1, characterized in that, In step (2), the acid used for pickling is 1 mol·L⁻¹. -1 The hydrochloric acid was used, and the pickling was performed three times.

6. The water treatment method based on non-radical synergistic oxidation according to claim 1, characterized in that, In step (2), the drying temperature is 60~70℃.

7. The water treatment method based on non-radical synergistic oxidation according to any one of claims 1 to 6, characterized in that, The persulfate is a potassium peroxymonosulfate complex salt 2KHSO5·KHSO4·K2SO4, and the pollutant in the water is diclofenac.

8. The application of Mn-CN catalyst in the non-radical synergistic oxidation and purification of pollutants in water through the decomposition of persulfate to form singlet oxygen and electron transfer, characterized in that... The preparation method of the Mn-CN catalyst includes the following steps: (1) Sodium alginate solution was added dropwise to calcium chloride solution, sieved, and calcium alginate hydrogel was obtained. Then it was immersed in hydrochloric acid and sonicated to complete the Ca2+ reaction. 2+ With H + After ion exchange and sieving, the resulting hydrogel is then added to a MnCl2 solution for impregnation with H2O. + With Mn 2+ Ion exchange, filtration, and drying yielded the Mn-based precursor; the concentration of the MnCl2 solution was 0.08–0.12 M. (2) The Mn-based precursor is mixed with urea, and then calcined in a nitrogen atmosphere, acid washed to remove surface Mn ions, washed with water until neutral, and dried to obtain the Mn-CN catalyst; the mass ratio of the Mn-based precursor to the urea is 3~5:

1.

9. The application according to claim 8, characterized in that, The persulfate is a potassium peroxymonosulfate complex salt 2KHSO5·KHSO4·K2SO4, and the pollutant in the water is diclofenac.

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