A photo-fenton catalyst, a preparation method thereof and a wastewater treatment method

Abstract

The application relates to the technical field of wastewater treatment, and discloses a preparation method of a photo-Fenton catalyst, which comprises the following steps: firstly, mixing, dispersing rare earth oxide powder, iron salt and deionized water to prepare dispersion liquid one; secondly, mixing and dispersing carbon nanotubes and deionized water to prepare dispersion liquid two; finally, mixing the dispersion liquid one and the dispersion liquid two, heating, evaporating the solvent and grinding to obtain the photo-Fenton catalyst; the rare earth oxide is at least one selected from oxides of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium; the iron salt is at least one selected from ferrous chloride, ferrous sulfate and ferrous nitrate; in the process of mixing the photo-Fenton catalyst prepared by the above method with hydrogen peroxide to treat wastewater, the concentration of hydroxyl radicals in water is improved to a certain extent, and the decomposition ability of organic matters is improved; in addition, the application further discloses a photo-Fenton catalyst and a wastewater treatment method.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a photo-Fenton catalyst, its preparation method, and a wastewater treatment method. Background Technology

[0002] The Fenton system used in wastewater treatment is a chemical treatment method. It involves exposing wastewater to air and adding oxidants such as iron salts and hydrogen peroxide, causing organic waste to be oxidized and decomposed into harmless substances. This treatment method is called the Fenton system, named after its inventor, Fenton. The principle of the Fenton system in wastewater treatment is to utilize the action of oxidants and iron salt catalysts to oxidize and decompose organic pollutants into harmless substances. In this process, iron salts are oxidized to trivalent Fe ions, which then combine with hydroxide ions from hydrogen peroxide to generate highly reactive hydroxyl radicals. These radicals can react with organic pollutants, breaking them down into smaller molecules, ultimately forming harmless substances. The Fenton system in wastewater treatment is characterized by high efficiency, economy, and environmental friendliness. It can effectively remove organic pollutants from wastewater, thereby reducing environmental pollution. At the same time, the Fenton system is also an economical treatment method because it uses low-cost chemicals and has relatively stable treatment effects. Furthermore, the Fenton system can be applied to the treatment of different types of wastewater, including industrial wastewater, agricultural wastewater, and domestic wastewater. In summary, the Fenton system used in wastewater treatment is a chemical treatment method that uses oxidants and iron salt catalysts to oxidize and decompose organic pollutants into harmless substances. The Fenton system is characterized by high efficiency, economy, and environmental friendliness, making it a suitable treatment method for various types of wastewater.

[0003] In her master's thesis, "Preparation of Rare Earth-Fe3O4-CD Composite Materials and Performance Study on Catalytic Hydrogen Peroxide Degradation of Cationic Dyes," Wang Xinyi of Donghua University prepared two rare earth element-doped Fenton catalysts, La-Fe3O4-CD and Ce-Fe3O4-CD. The thesis also investigated four factors affecting the adsorption effect of the La-Fe3O4-CD and Ce-Fe3O4-CD composite materials on the cationic blue dye X-GRL: adsorption time, initial solution pH, composite material dosage, and initial dye concentration. The following conclusions were drawn:

[0004] The optimal adsorption time for cationic blue X-GRL by both La-Fe3O4-CD and Ce-Fe3O4-CD composites was 90 min. The optimal pH for the adsorption reaction was 4 and 8, respectively, consistent with the Zeta potential analysis results. To ensure high material utilization efficiency, the optimal initial dye concentration and optimal composite material dosage for the adsorption reaction of both La-Fe3O4-CD and Ce-Fe3O4-CD composites were 20 mg / L. Under optimal adsorption conditions, the adsorption rates of dye by La-Fe3O4-CD and Ce-Fe3O4-CD composites reached 92.26% and 77.79%, respectively.

[0005] Chen Jianxin, Wei Peiyao, Zhang Yiwei, et al., in the article "LaFe" published in Volume 46, Issue 4 of the Journal of Nanchang University 0.5 Co 0.5 In the article "O3 Photo-assisted Fenton Catalytic Performance and Catalytic Mechanism", LaFe was first synthesized via the sol-gel method. 0.5 Co 0.5 O3 catalyst, subsequently, this literature in LaFe 0.5 Co 0.5 The O3 photo-assisted Fenton catalysis mechanism was also explored in relation to UV + LaFe. 0.5 Co 0.5 The graph showing the concentration changes of H2O2 and hydroxyl radicals during the decolorization of Orange II in the O3+H2O2 reaction system shows that the concentration of hydroxyl radicals reaches its peak at 30 min, specifically about 9 μmol / L. In the existing technology, we believe that hydroxyl radicals, as a substance with strong oxidizing properties, are one of the main factors that promote the decomposition of organic matter in wastewater into inorganic matter.

[0006] Chinese patent application 202310618739.8 discloses a method for treating leachate wastewater using the Fenton process, specifically involving adding hydrogen peroxide and a photo-Fenton catalyst to leachate wastewater with a pH of 3-11, and then carrying out a photocatalytic degradation reaction under ultraviolet light irradiation; the photo-Fenton catalyst includes La x M 1-x Fe y N 1-y O3 / (Li z Sr 1-z TiO3 composite material; where x, y, and z are all 0.05-0.95; M is a rare earth element or alkaline earth element; N is a transition metal element. Using this scheme to treat leachate wastewater can effectively remove CODcr, TP, and TN in a short time, and can achieve good treatment results in a wide pH range.

[0007] Meanwhile, observing the COD removal rate, TP removal rate, TN removal rate, and other data of the scheme, it can be seen that the scheme has a good wastewater treatment effect. However, the scheme does not show any improvement in the concentration of hydroxyl radicals or the lifetime of hydroxyl radicals.

[0008] The problem this solution aims to solve is: how to develop a photo-Fenton catalyst with a high concentration of hydroxyl radicals in wastewater treatment processes. Summary of the Invention

[0009] The purpose of this application is to develop a photo-Fenton catalyst with a high concentration of hydroxyl radicals in wastewater treatment processes.

[0010] Unless otherwise specified in this application: nM represents nanomoles per liter, μM represents micromoles per liter, mM represents millimoles per liter, and M represents moles per liter;

[0011] To achieve the above objectives, this application provides a method for preparing a photo-Fenton catalyst, comprising the following steps:

[0012] Step 1: Mix and disperse rare earth oxide powder, iron salt and deionized water to prepare dispersion one;

[0013] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0014] Step 3: Mix the first dispersion obtained in Step 1 and the second dispersion obtained in Step 2, heat and evaporate the solvent, and grind to obtain the photo-Fenton catalyst.

[0015] The rare earth oxide is selected from at least one of the oxides of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium;

[0016] The iron salt is selected from at least one of ferrous chloride, ferrous sulfate, and ferrous nitrate;

[0017] The mass ratio of the rare earth oxides, iron salts, and carbon nanotubes is 0.8-1.2:0.8-1.2:10.

[0018] Preferably, the rare earth oxide is a mixture of lanthanum oxide, gadolinium oxide, and yttrium oxide, wherein the mass ratio of lanthanum oxide, gadolinium oxide, and yttrium oxide is 3-5:2-5:2.

[0019] Preferably, step 3 specifically involves: mixing the first dispersion obtained in step 1 and the second dispersion obtained in step 2, heating them at 80-120°C for 3-5 hours to evaporate the solvent, obtaining an intermediate, and then grinding the intermediate to obtain a photo-Fenton catalyst.

[0020] In addition, this application also discloses a photo-Fenton catalyst, which is prepared by the above-described method for preparing photo-Fenton catalysts.

[0021] Preferably, the particle size of the photo-Fenton catalyst is 3-20 μm.

[0022] In addition, this application also discloses a wastewater treatment method in which a support loaded with the above-mentioned photo-Fenton catalyst is mixed with hydrogen peroxide and added to the wastewater to be treated.

[0023] Preferably, the support for the photo-Fenton catalyst is nickel foam loaded with the photo-Fenton catalyst, and the mass ratio of the nickel foam to the photo-Fenton catalyst is 10:0.1-3.

[0024] The mass ratio of hydrogen peroxide to the photo-Fenton catalyst supported on nickel foam is 100:0.1-3.

[0025] Preferably, the support loaded with the photo-Fenton catalyst is prepared by the following steps:

[0026] Step A1: Disperse the photo-Fenton catalyst in deionized water to obtain dispersion three;

[0027] Step A2: Add nickel foam and surfactant to dispersion 3, and heat in water at 60-80℃ for 6-8 hours to obtain a support loaded with photo-Fenton catalyst.

[0028] Preferably, in step A1, the photo-Fenton catalysts are large-particle-size photo-Fenton catalysts and small-particle-size photo-Fenton catalysts;

[0029] The particle size of the large-particle-size photo-Fenton catalyst is 5-10 μm;

[0030] The particle size of the small-particle-size photo-Fenton catalyst is 3-5 μm and does not include 5 μm;

[0031] The mass ratio of the large-particle-size photo-Fenton catalyst to the small-particle-size photo-Fenton catalyst is 1:2-3.

[0032] Preferably, the surfactant is citric acid or ascorbic acid, the total mass ratio of citric acid and ascorbic acid to the mass ratio of photo-Fenton catalyst is 1:1-30, and the mass ratio of citric acid to ascorbic acid is 1:1.

[0033] The beneficial effects of this application are: rare earth oxides such as lanthanum oxide, gadolinium oxide, and yttrium oxide, as components of the catalyst, can provide active sites, which are conducive to the catalytic reaction. On the catalyst surface, harmful substances in organic wastewater can be adsorbed, thereby promoting the contact between harmful substances and hydroperoxides, which is conducive to the generation of hydroxyl radicals;

[0034] Under light irradiation, these oxides can absorb energy and excite electrons, thereby generating electron-hole pairs. These excited electron-hole pairs can participate in redox reactions and promote the generation of hydroxyl radicals. These radicals can react with harmful substances in organic wastewater, thereby degrading organic matter.

[0035] Furthermore, rare earth oxides such as lanthanum oxide, gadolinium oxide, and yttrium oxide, as components of catalysts, can participate in the generation of photogenerated electron-hole pairs. These excited-state electron-hole pairs can participate in electron transfer processes, thereby extending the lifetime of hydroxyl radicals. Under light irradiation, these oxides can absorb energy, excite electrons, and form electron-hole pairs. These electron-hole pairs can react with water or hydroperoxides to generate hydroxyl radicals. Due to the presence of these electron-hole pairs, the regeneration process of hydroxyl radicals is prolonged, thus extending the lifetime of hydroxyl radicals. Detailed Implementation

[0036] In the description of this invention, it should be noted that unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] Step 1: Mix and disperse lanthanum oxide powder, ferrous chloride and deionized water to obtain dispersion one;

[0040] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0041] Step 3: Mix the first dispersion obtained in Step 1 and the second dispersion obtained in Step 2 and heat at 80°C for 3 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0042] The mass ratio of lanthanum oxide powder, ferrous chloride, and carbon nanotubes is 0.8:0.8:10.

[0043] Example 2

[0044] Step 1: Mix and disperse cerium oxide powder, ferrous sulfate and deionized water to obtain dispersion one;

[0045] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0046] Step 3: Mix the first dispersion obtained in Step 1 and the second dispersion obtained in Step 2 and heat at 120°C for 5 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0047] The mass ratio of cerium oxide powder, ferrous sulfate, and carbon nanotubes is 1.2:1.2:10.

[0048] Example 3

[0049] Step 1: Mix and disperse yttrium oxide powder, ferrous sulfate and deionized water to obtain dispersion one;

[0050] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0051] Step 3: Mix the first dispersion prepared in Step 1 and the second dispersion prepared in Step 2 and heat at 100°C for 4 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0052] The mass ratio of yttrium oxide powder, ferrous sulfate, and carbon nanotubes is 1:1:10.

[0053] Example 4

[0054] Step 1: Mix and disperse lanthanum oxide powder, gadolinium oxide powder, ferrous sulfate and deionized water to obtain dispersion one;

[0055] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0056] Step 3: Mix the first dispersion prepared in Step 1 and the second dispersion prepared in Step 2 and heat at 100°C for 4 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0057] The total mass ratio of the lanthanum oxide powder and gadolinium oxide powder to the mass ratio of ferrous sulfate and carbon nanotubes is 1:1:10;

[0058] The mass ratio of lanthanum oxide powder to gadolinium oxide powder is 1:1.

[0059] Example 5

[0060] Step 1: Mix and disperse lanthanum oxide powder, gadolinium oxide powder, yttrium oxide powder, ferrous sulfate and deionized water to obtain dispersion one;

[0061] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0062] Step 3: Mix the first dispersion prepared in Step 1 and the second dispersion prepared in Step 2 and heat at 100°C for 4 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0063] The total mass ratio of lanthanum oxide powder, gadolinium oxide powder, and yttrium oxide powder to ferrous sulfate and carbon nanotubes is 1:1:10.

[0064] The mass ratio of the lanthanum oxide powder, gadolinium oxide powder, and yttrium oxide powder is 1:1:1.

[0065] Example 6

[0066] Step 1: Mix and disperse lanthanum oxide powder, gadolinium oxide powder, yttrium oxide powder, ferrous sulfate and deionized water to obtain dispersion one;

[0067] Step 2: Mix and disperse carbon nanotubes with deionized water to obtain dispersion II;

[0068] Step 3: Mix the first dispersion prepared in Step 1 and the second dispersion prepared in Step 2 and heat at 100°C for 4 hours to evaporate the solvent to obtain an intermediate. Then grind the intermediate to obtain the photo-Fenton catalyst.

[0069] The total mass ratio of lanthanum oxide powder, gadolinium oxide powder, and yttrium oxide powder to ferrous sulfate and carbon nanotubes is 1:1:10.

[0070] The mass ratio of lanthanum oxide powder, gadolinium oxide powder, and yttrium oxide powder is 4:3:2.

[0071] Comparative Example 1

[0072] It is basically the same as Example 1, except that the same mass of cobalt oxide powder is used instead of lanthanum oxide powder.

[0073] Comparative Example 2

[0074] The process is basically the same as in Example 1, except that in step 1, lanthanum oxide powder, cobalt oxide powder, ferrous chloride and deionized water are mixed and dispersed to obtain dispersion one.

[0075] The total mass ratio of the lanthanum oxide powder and cobalt oxide powder to the mass ratio of ferrous chloride and carbon nanotubes is 1:1:10.

[0076] The mass ratio of lanthanum oxide powder to cobalt oxide powder is 1:1.

[0077] Comparative Example 3

[0078] It is basically the same as Example 1, except that activated carbon powder is used instead of carbon nanotubes.

[0079] Preparation Examples 1-9

[0080] Step A1: Disperse the photo-Fenton catalysts with a particle size of 2 μm obtained in Examples 1-6 and Comparative Examples 1-3 in deionized water to obtain dispersion three;

[0081] Step A2: Add nickel foam and ascorbic acid to dispersion three, and heat in water at 70°C for 7 hours to obtain a support loaded with photo-Fenton catalyst;

[0082] The mass ratio of the nickel foam to the photo-Fenton catalyst is 10:1;

[0083] The mass ratio of ascorbic acid to photo-Fenton catalyst is 1:10.

[0084] Preparation Example 10

[0085] Step A1: Disperse the 4 μm photo-Fenton catalyst obtained in Example 6 in deionized water to obtain dispersion three;

[0086] Step A2: Add nickel foam and surfactant to dispersion three, and heat in water at 70°C for 7 hours to obtain a support loaded with photo-Fenton catalyst.

[0087] The mass ratio of the nickel foam to the photo-Fenton catalyst is 10:1;

[0088] The mass ratio of ascorbic acid to photo-Fenton catalyst is 1:10.

[0089] Preparation Example 11

[0090] Step A1: Disperse the 4 μm and 8 μm photo-Fenton catalysts obtained in Example 6 in deionized water to obtain dispersion three;

[0091] Step A2: Add nickel foam and ascorbic acid to dispersion three, and heat in water at 70°C for 7 hours to obtain a support loaded with photo-Fenton catalyst;

[0092] The mass ratio of the nickel foam to the photo-Fenton catalyst is 10:1;

[0093] The mass ratio of ascorbic acid to photo-Fenton catalyst is 1:10.

[0094] Preparation Example 12

[0095] Step A1: Disperse the 4 μm and 8 μm photo-Fenton catalysts obtained in Example 6 in deionized water to obtain dispersion three;

[0096] Step A2: Add nickel foam, citric acid, and ascorbic acid to dispersion three, and heat in water at 70°C for 7 hours to obtain a support loaded with photo-Fenton catalyst.

[0097] The mass ratio of the nickel foam to the photo-Fenton catalyst is 10:1;

[0098] The total mass ratio of citric acid and ascorbic acid to the photo-Fenton catalyst is 1:10.

[0099] The mass ratio of citric acid to ascorbic acid is 1:1.

[0100] Wastewater treatment process and performance testing:

[0101] The nickel foam supported on photo-Fenton catalyst prepared in Examples 1-12 was mixed with hydrogen peroxide and added to the wastewater to be treated. The mass ratio of hydrogen peroxide to the photo-Fenton catalyst supported on nickel foam was 100:1 and the amount of hydrogen peroxide added per ton of wastewater was about 1.5L.

[0102] Hydroxyl radical concentration test: Wastewater samples were taken before treatment, 30 minutes after treatment, 90 minutes after treatment, and 150 minutes after treatment, and the hydroxyl radical concentration of the wastewater samples was tested using fluorescence spectrophotometry in scanning mode.

[0103] Wherein, the scanning emission wavelength is 2400 nm / min; the PMT voltage is 700 V; the fixed excitation wavelength is 315 nm, the scanning emission wavelength range is 220–600 nm, and the excitation and emission slit width is 5 nm. The results are shown in Table 1.

[0104] Table 1

[0105]

[0106]

[0107] Results analysis:

[0108] 1. As can be seen from the preparation examples 1-3, when the photo-Fenton catalyst prepared in Examples 1-3 and hydrogen peroxide are used together to treat wastewater, the difference in hydroxyl radical concentration between Examples 1-3 is not significant;

[0109] 2. As can be seen from Preparation Example 1 and Preparation Examples 4-6, when the rare earth oxides are lanthanum oxide and gadolinium oxide, the concentration of hydroxyl radicals is significantly lower than that of the combination of lanthanum oxide, gadolinium oxide and yttrium oxide;

[0110] When the mass ratio of lanthanum oxide, gadolinium oxide and yttrium oxide was further adjusted in Example 6, the concentration of hydroxyl radicals increased to a certain extent. We believe that the combination of lanthanum oxide, gadolinium oxide and yttrium oxide increases the number of active sites in the Fenton system, thereby improving the decomposition efficiency and utilization of H2O2, and thus increasing the number of hydroxyl radicals.

[0111] 3. As can be seen from Preparation Examples 7-8, when other metal oxides are used to replace rare earth oxides, the number of hydroxyl radicals tends to decrease to a certain extent. When other metal oxides and rare earth oxides are used in combination, although the concentration of hydroxyl radicals increases compared to using other metal oxides alone, there is still a certain gap compared to Preparation Example 1.

[0112] 4. As can be seen from Preparation Examples 10-12, when the photo-Fenton catalysts prepared in Example 6 with different particle sizes are used together with hydrogen peroxide, the concentration of hydroxyl radicals does not show an obvious trend of change.

[0113] When different particle sizes of photo-Fenton catalysts were mixed, the sample achieved a certain advantage in the concentration of hydroxyl radicals in the wastewater 150 min after treatment. We believe that when using photo-Fenton catalysts with mixed particle sizes, the smaller particle size photo-Fenton catalyst can participate in the reaction more quickly and promote the decomposition of hydrogen peroxide, while the larger particle size photo-Fenton catalyst enters the reaction peak relatively slowly, thus prolonging the reaction time.

[0114] Furthermore, when citric acid and ascorbic acid were used in combination, the reaction time was further extended. We believe that the combined use of surfactants reduced the rate at which the photo-Fenton catalyst detached from the support, thereby delaying the consumption of the photo-Fenton catalyst. At the same time, according to the data in Table 1, although Preparation Example 12 had a stronger ability to maintain the concentration of hydroxyl radicals, its peak value was also lower than that of Preparation Example 11.

Claims

1. A method for preparing a photo-Fenton catalyst, characterized by, The method comprises the following steps: Step 1: mixing and dispersing rare earth oxide powder and iron salt in deionized water to obtain a dispersion solution one; Step 2: mixing and dispersing carbon nanotubes in deionized water to obtain a dispersion solution two; Step 3: mixing the dispersion solution one obtained in step 1 and the dispersion solution two obtained in step 2, heating and evaporating the solvent, and grinding to obtain the photo-Fenton catalyst. The rare earth oxide is a mixture of lanthanum oxide, gadolinium oxide and yttrium oxide, and the mass ratio of the lanthanum oxide, the gadolinium oxide and the yttrium oxide is 3-5:2-5:

2. The iron salt is at least one selected from ferrous chloride, ferrous sulfate and ferrous nitrate. The mass ratio of the rare earth oxide, the iron salt and the carbon nanotubes is 0.8-1.2:0.8-1.2:

10.

2. The method of preparing a photo-Fenton catalyst according to claim 1, characterized in that, The step 3 is specifically: mixing the dispersion solution one obtained in step 1 and the dispersion solution two obtained in step 2, heating at 80-120℃ for 3-5h to evaporate the solvent, obtaining an intermediate, and then grinding the intermediate to obtain the photo-Fenton catalyst.

3. A photo-Fenton catalyst, characterized in that, The photo-Fenton catalyst is prepared by the method of any one of claims 1 or 2.

4. The photo-Fenton catalyst according to claim 3, characterized in that, The particle size of the photo-Fenton catalyst is 3-20μm.

5. A method of treating wastewater, characterized by, The carrier loaded with the photo-Fenton catalyst of claim 3 or 4 is mixed with hydrogen peroxide and put into the wastewater to be treated.

6. The wastewater treatment method according to claim 5, characterized by, The carrier loaded with the photo-Fenton catalyst is foam nickel loaded with the photo-Fenton catalyst, and the mass ratio of the foam nickel to the photo-Fenton catalyst loaded thereon is 10:0.1-3. The mass ratio of the hydrogen peroxide to the photo-Fenton catalyst loaded on the foam nickel is 100:0.1-3.

7. The wastewater treatment method according to claim 6, characterized by, The carrier loaded with the photo-Fenton catalyst is prepared by the following steps: Step A1: dispersing the photo-Fenton catalyst in deionized water to obtain a dispersion solution three; Step A2: putting the foam nickel and a surfactant into the dispersion solution three, heating at a temperature of 60-80℃ for 6-8h to obtain the carrier loaded with the photo-Fenton catalyst.

8. The wastewater treatment method according to claim 7, characterized by, In step A1, the photo-Fenton catalysts are a large-particle-size photo-Fenton catalyst and a small-particle-size photo-Fenton catalyst, respectively; The particle size of the large-particle-size photo-Fenton catalyst is 5-10μm; The particle size of the small-particle-size photo-Fenton catalyst is 3-5μm and does not include 5μm; The mass ratio of the large-particle-size photo-Fenton catalyst to the small-particle-size photo-Fenton catalyst is 1:2-3.

9. The water treatment method of claim 7, wherein, The surfactant is citric acid and ascorbic acid, the mass ratio of the total mass of the citric acid and the ascorbic acid to the mass of the photo-Fenton catalyst is 1:1-30, and the mass ratio of the citric acid to the ascorbic acid is 1:1.

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