A photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction, its preparation method and application

Abstract

The application discloses a low-H2O2-consumption nitrogen-defect and potassium-doped FeOCl / NvCN heterojunction photo-Fenton catalyst, a preparation method and application thereof, and belongs to the technical field of photochemical materials. 3+ And the slow oxidation-reduction cycle between Fe 2+ And the high photo-generated carrier recombination rate limit the application of FeOCl, and the problem that tetracycline hydrochloride (TC) in wastewater is difficult to degrade. The preparation method of the low-H2O2-consumption nitrogen-defect and potassium-doped FeOCl / NvCN heterojunction photo-Fenton catalyst utilizes an in-situ deposition method to prepare the photo-Fenton catalyst with the FeOCl / NvCN heterojunction, NvCN is prepared first, deionized water is added into a crucible, FeCl3.6H2O is added into the crucible to obtain a ferric chloride solution, the NvCN obtained in the step 4 is added into the solution to obtain a mixed liquid, and then ultrasonic treatment is conducted to obtain the low-H2O2-consumption nitrogen-defect and potassium-doped FeOCl / NvCN heterojunction photo-Fenton catalyst. The catalyst can be used for degradation of tetracycline hydrochloride. FeOCl / NvCN shows a good practical application prospect in actual water bodies.

Description

Technical Field

[0001] This invention belongs to the field of photochemical materials technology, specifically relating to the preparation method and application of a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction. Background Technology

[0002] H2O2-based AOP, such as the Fenton process, utilizes Fe 2+ The highly active ·OH generated by the reaction with H2O2 can effectively treat organic pollutants and also exhibits excellent removal efficiency for recalcitrant substances, showing great application potential in the field of water treatment. However, traditional ferrous-based Fenton catalysts are limited by narrow pH operating ranges (2-4) and low H2O2 utilization. Combining photocatalysis with the Fenton process holds promise for solving these problems. Although photo-Fenton technology shows significant advantages, its efficiency improvement mainly depends on the amount of oxidant H2O2 used. Generally, for antibiotics at a concentration of mg / L, 2-100 mM H2O2 is required to achieve satisfactory removal efficiency. Developing visible-light-responsive photo-Fenton catalysts with excellent photocatalytic activity and low H2O2 usage for water remediation remains a challenge.

[0003] FeOCl faces two obstacles in optical Fenton applications: Fe 3+ and Fe 2+ The slow redox cycle and high recombination rate of photogenerated carriers limit its applications. To address these issues, FeOCl can be combined with semiconductors to construct heterostructures, utilizing photogenerated electrons to accelerate the recombination of Fe. 3+ / Fe 2+ cycle.

[0004] Graphitic carbon nitride (g-C3N4) is a metal-free polymer semiconductor that has attracted widespread attention in the field of photocatalysis due to its simple synthesis, environmental friendliness, and high chemical stability. However, g-C3N4 also has drawbacks such as easy recombination of photogenerated carriers and a relatively narrow visible light absorption range, and its photocatalytic activity needs further improvement.

[0005] No one in the current technology has proposed combining potassium doping and NvCN with nitrogen vacancies with FeOCl to prepare catalysts. Summary of the Invention

[0006] The technical problem to be solved by this invention is:

[0007] The purpose of this invention is to provide a nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction photo-Fenton catalyst with low H2O2 consumption, its preparation method, and its application, in order to solve the problems of excessive H2O2 consumption, high application cost, slow redox cycle between Fe3+ and Fe2+, high recombination rate of photogenerated carriers limiting the application of FeOCl, and the difficulty in degrading tetracycline hydrochloride (TC) in wastewater during the application of existing photo-Fenton catalysts.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] A method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient, and potassium-doped FeOCl / NvCN heterojunction, comprising the following steps:

[0010] Step 1: Dissolve a certain amount of KOH in deionized water to obtain a deionized water KOH solution with a mass-volume concentration of 0.008-0.01 g / mL (each mL of KOH solution contains 0.008-0.01 g KOH);

[0011] Step 2: Add melamine powder to the solution described in Step 1 and stir to make the solution uniform. The mass ratio of KOH to melamine is (0.35~3.5):100.

[0012] Step 3: Place the mixed solution of KOH and melamine obtained in Step 2 in an oven and dry for 6-12 hours to obtain powder;

[0013] Step 4: Grind the dried powder thoroughly and place it in a muffle furnace to calcine at 600°C for 2-3 hours at a heating rate of 3-5°C per minute to obtain NvCN (powder);

[0014] Step 5: Add deionized water to the crucible, then add FeCl3·6H2O (powder) to the crucible to obtain ferric chloride solution, and then add NvCN obtained in step 4 to the solution to obtain a mixed liquid;

[0015] Step 6: Sonicate the mixture to ensure thorough mixing;

[0016] Step 7: After the crucible is thoroughly dried in an oven, the powder is obtained and then ground to obtain fine powder.

[0017] Step 8: Place the obtained fine powder in a muffle furnace and heat it to 250°C for 2-3 hours, with a heating rate of 3-5°C per minute; to obtain a composite material (powder) with FeOCl / NvCN heterostructure;

[0018] Step 9: After repeatedly washing the composite material with FeOCl / NvCN heterojunction with acetone and deionized water to remove residual ferric ions, the material is dried to obtain a photo-Fenton catalyst with low H2O2 consumption, nitrogen defects, and potassium doped FeOCl / NvCN heterojunction.

[0019] Furthermore, in step 2, the mass ratio of KOH to melamine is 1:100.

[0020] Furthermore, in step 2, the solution is stirred for 15–20 minutes to ensure homogeneity.

[0021] Further, in step 3, the product is dried in an oven at a drying temperature of 70–85°C for 6–10 hours.

[0022] Furthermore, in step 5, ultrasonic treatment is performed for 1 to 3 hours to ensure thorough mixing.

[0023] A photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction, said catalyst being prepared by the method described above.

[0024] Further, the mass ratio of FeCl3·6H2O to NvCN is 0.4–2.0. Further, the catalyst is constructed by doping g-C3N4 with potassium and introducing nitrogen vacancies, and then combining it with FeOCl to form a FeOCl / NvCN heterostructure. The FeOCl / NvCN heterostructure is a Z-type heterojunction.

[0025] Application of a nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction photo-Fenton catalyst with low H2O2 consumption for the degradation of tetracycline hydrochloride (TC). The FeOCl / NvCN heterojunction photo-Fenton catalyst is added to tetracycline antibiotic wastewater at a dosage of 0.025 g / L to 0.20 g / L. The solution is first magnetically stirred in a dark room at a rate of 450 r / min to 600 r / min until adsorption and desorption equilibrium is reached. Then, photo-Fenton catalytic oxidation is carried out under the irradiation of a xenon lamp with a power of 300 W to 350 W.

[0026] The present invention has the following beneficial technical effects:

[0027] This invention successfully synthesized a FeOCl / NvCN photo-Fenton catalyst and characterized its chemical properties and morphology. FeOCl / NvCN exhibited higher H2O2 activation catalytic activity than the single component. The method proposed in this invention improves catalyst activity while significantly reducing H2O2 consumption. This invention provides new insights for constructing efficient photo-Fenton catalysts with high H2O2 utilization. FeOCl / NvCN shows promising practical application prospects in real water bodies.

[0028] The introduction of nitrogen vacancies in this invention effectively improves the light absorption range of g-C3N4 and enhances the photogenerated carrier separation efficiency. Introducing nitrogen vacancies encourages more unsaturated ligand atoms to act as reaction sites, activating reactant molecules and achieving selective chemisorption, thereby improving catalytic performance. The combination of potassium doping and nitrogen vacancies is expected to further enhance the catalytic activity of g-C3N4.

[0029] FeOCl faces two obstacles in optical Fenton applications: Fe 3+ and Fe 2+ The slow redox cycle and high photogenerated carrier recombination rate limit its applications. This invention constructs a heterostructure by combining FeOCl with a semiconductor, utilizing photogenerated electrons to accelerate Fe… 3+ / Fe 2+ Looping solves these problems perfectly.

[0030] The catalyst described in this invention is used for the degradation of tetracycline hydrochloride (TC) and provides a new approach to TC removal. The FeOCl / NvCN photo-Fenton catalyst improves catalyst activity while significantly reducing H2O2 consumption, providing new insights into constructing highly efficient photo-Fenton catalysts with high H2O2 utilization. The method of this invention is simple to operate, with a straightforward process and low consumption. Attached Figure Description

[0031] Figure 1 In Example 1 of this invention, the morphology of the prepared sample was analyzed by scanning electron microscopy.

[0032] Figure 2 This invention presents a set of spectra. The surface chemical composition of CN, NvCN, FeOCl, and FeOCl / NvCN was further measured by XPS, and the presence of N vacancies was verified by EA (organic elemental analysis).

[0033] Figure 3 A set of spectra (X-ray diffraction pattern on the left, infrared spectrum on the right) were used to investigate the phase structure, chemical bonding, and functional groups of CN, NvCN, FeOCl / NvCN, and FeOCl catalysts by XRD and FT-IR.

[0034] Figure 4 This figure shows the specific surface area and pore size distribution of FeOCl / NvCN analyzed by BET adsorption experiments.

[0035] Figure 5 The effect of different samples on the degradation of TC by the catalyst is shown in the figure.

[0036] Figure 6The transport dynamics of photogenerated carriers on CN, MvCN, and FeOCl / NvCN were analyzed using UV-Vis (ultraviolet-visible diffuse reflectance spectroscopy), EIS (impedance spectroscopy), and PL (fluorescence) spectroscopy.

[0037] Figure 7 The graph shows a comparison of the catalytic efficiency of FeOCl / NvCN with that of the reported photo-Fenton catalyst.

[0038] Figure 8 The existence of the FeOCl / NvCN heterojunction was verified by TEM (scanning lens image).

[0039] Figure 9 This is a mechanism diagram of a Z-type heterojunction. Detailed Implementation

[0040] Appendix Figure 1-9 The implementation of the present invention is described as follows:

[0041] Specific Implementation Method 1: A method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction, wherein the method utilizes an in-situ deposition method to prepare a photo-Fenton catalyst with a FeOCl / NvCN heterojunction, and includes the following steps:

[0042] Step 1: Dissolve a certain amount of KOH in deionized water to obtain a deionized water KOH solution with a mass-volume concentration of 0.008 g / mL, where each mL of KOH solution contains 0.008 g / mL.

[0043] Step 2: Add melamine powder to the solution described in Step 1 and stir to make the solution uniform. The mass ratio of KOH to melamine is 1:100. Stir for 15-20 minutes in Step 2 to make the solution uniform.

[0044] Step 3: Place the mixed solution of KOH and melamine obtained in step 2 in an oven and dry for 6-12 hours to obtain powder; dry in an oven at a drying temperature of 75℃ for 6 hours in step 3.

[0045] Step 4: Grind the dried powder thoroughly and place it in a muffle furnace to 600°C for 2 hours. The heating rate is 3-5°C per minute to obtain NvCN (powder).

[0046] Step 5: Add deionized water to the crucible, then add FeCl3·6H2O (powder) to the crucible to obtain ferric chloride solution, then add NvCN obtained in step 4 to the solution to obtain a mixed liquid; perform ultrasonic treatment for 2 hours in step 5 to ensure thorough mixing.

[0047] Step 6: Sonicate the mixture to ensure thorough mixing;

[0048] Step 7: After the crucible is thoroughly dried in an oven, the powder is obtained and then ground to obtain fine powder.

[0049] Step 8: Place the obtained fine powder in a muffle furnace and heat it to 250°C for 2 hours, with a heating rate of 3°C per minute; to obtain a composite material (powder) with FeOCl / NvCN heterostructure;

[0050] Step 9: After repeatedly washing the composite material with the FeOCl / NvCN heterojunction with acetone and deionized water to remove residual ferric ions, the material is dried to obtain a photo-Fenton catalyst with low H2O2 consumption, nitrogen defects, and potassium doped FeOCl / NvCN heterojunction. Subsequent examples are based on this.

[0051] Specific Implementation Method Two: A method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient, and potassium-doped FeOCl / NvCN heterojunction, specifically comprising the following steps:

[0052] Step 1: Preparation of potassium-doped nitrogen vacancy g-C3N4 (NvCN)

[0053] NvCN was prepared by thermal polymerization: 0.25 g of KOH was dissolved in 30 mL of deionized water, 15 g of melamine was added, and the mixture was stirred for 15 min to make the solution homogeneous. The solution was then dried in an oven at 75 °C for 6 h. The dried powder was then thoroughly ground and placed in a muffle furnace, heated to 600 °C at a heating rate of 3 °C / min, and calcined for 2 h.

[0054] Step 2, Preparation of FeOCl / NvCN

[0055] FeOCl / NvCN was prepared by in-situ deposition. 0.25 g of FeCl3·6H2O was dissolved in 10 mL of deionized water, then 0.25 g of NvCN was added, and the mixture was sonicated for 1 h to ensure thorough mixing. After thorough drying in a 75°C oven, the mixture was ground. The resulting powder was placed in a muffle furnace and calcined at 250°C for 2 h at a heating rate of 3°C / min. The resulting sample was washed repeatedly with acetone and deionized water and then dried.

[0056] A FeOCl / NvCN photo-Fenton catalyst was successfully synthesized, and its chemical properties and morphology were characterized.

[0057] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0058] Example 1:

[0059] Dissolve 0.25 g of KOH in 30 mL of deionized water, add 15 g of melamine, and stir for 15 min to make the solution homogeneous. Dry in an oven at 75 °C for 6 h. Grind the dried powder thoroughly, place it in a muffle furnace, and calcine it to 600 °C for 2 h at a heating rate of 3 °C / min.

[0060] Example 2:

[0061] In contrast, the preparation process of pure g-C3N4(CN) is similar to that of NvCN, except that KOH is not added during the preparation process.

[0062] Example 3:

[0063] FeOCl / NvCN was prepared by in-situ deposition. 0.25 g of FeCl3·6H2O was dissolved in 10 mL of deionized water, then 0.25 g of NvCN was added, and the mixture was sonicated for 1 h to ensure thorough mixing. After thorough drying in a 75°C oven, the mixture was ground. The resulting powder was placed in a muffle furnace and calcined at 250°C for 2 h at a heating rate of 3°C / min. The sample was then washed repeatedly with acetone and deionized water and dried.

[0064] Example 4:

[0065] In contrast, pure FeOCl was prepared using a procedure similar to that in Example 3 without the addition of NvCN.

[0066] Figure 1 The morphology of the prepared samples was analyzed using scanning electron microscopy, confirming the heterojunction interface between NvCN and FeOCl. The lamellar structure increases the active sites on the NvCN surface, which is beneficial for improving the photo-Fenton catalytic efficiency. EDS spectroscopy confirmed the presence of C, Cl, Fe, N, O, and K elements in FeOCl / NvCN, and the elemental distribution was uniform. This result further demonstrates the successful formation of a heterojunction between NvCN and FeOCl.

[0067] Figure 2 (a) The XPS spectrum of FeOCl / NvCN shows the presence of C, N, K, Fe, O and Cl elements. Figure 2 (b) Organic elemental analysis (EA) and XPS analysis showed that the C / N atomic ratios in CN and NvCN were 0.5564 and 0.5629, respectively, indicating the absence of nitrogen atoms in the NvCN sample. Similar results were also reflected in the XPS data, where the C / N atomic ratios in CN and NvCN were 0.5336 and 0.7095, respectively. Although the XPS data are not very accurate, their trend is consistent with that of EA. The above results further illustrate the introduction of nitrogen vacancies in CN.

[0068] Figure 2 (c) The peak area of ​​XPS is used to determine the location of N vacancies. Compared with pure CN, the peak area of ​​NvCN at C=NC decreases from 76.01 to 73.74. The significant decrease in peak area indicates that N vacancies are formed at C=NC.

[0069] Figure 3 Two diffraction peaks at 13.1 and 27.3 Å were observed in CN, NvCN, and FeOCl / NvCN, corresponding to the conjugated structure (100) of g-C3N4 and the interfacial stacking (002) of the heptaazine network, respectively. Upon addition of KOH, the intensity of these peaks decreased. Furthermore, in NvCN and FeOCl / NvCN, the diffraction peak at (002) shifted to a lower diffraction angle, which can be attributed to the reduced interlayer distance due to the insertion of K atoms into the g-C3N4 layer. These results demonstrate the good coexistence of FeOCl and NvCN.

[0070] Figure 4 The specific surface area and pore size distribution curves of FeOCl / NvCN were investigated using BET adsorption experiments. Figure 4 As shown in (a), FeOCl / NvCN exhibits a typical Type IV isotherm and has an H3 model hysteresis loop, proving the presence of a mesoporous structure in the sample. Pore size distribution curve ( Figure 4 As shown in (b), the average pore size is 28.7575 nm. The BET surface area of ​​FeOCl / NvCN is 28.4082 m². 2 / g, a larger specific surface area can provide more active sites for the reaction.

[0071] Figure 5 In (a), the degradation efficiency of H2O2 on TC is 24%, while the photo-Fenton catalytic efficiency of CN is only 41.74%. All NvCNs with added KOH have higher degradation efficiency on TC than pure CN, proving that the doping of K atoms effectively improves the photo-Fenton activity of CN. Figure 5 (b) shows that the degradation efficiency of FeOCl / NvCN is 87.73%.

[0072] Figure 6 In (a), it was observed in the ultraviolet-visible diffuse reflectance (Uv-vis) spectrum that the binding of FeOCl with NvCN enhanced the absorption of light, thereby improving the catalytic activity. Figure 6 (b) The smallest radius of curvature can be observed in the FeOCl / NvCN impedance spectrum, which indicates that the sample has the smallest charge transfer resistance and the best conductivity. Figure 6(c) shows the transport dynamics of photogenerated carriers on CN, MvCN, and FeOCl / NvCN analyzed by PL spectroscopy. FeOCl / NvCN exhibits the lowest PL emission peak intensity, further indicating that the heterojunction structure formed between FeOCl and NvCN significantly suppresses ee emission. - and h + The combination effectively improves catalytic performance.

[0073] Figure 7 By comparing the FeOCl / NvCN photo-Fenton catalyst with previously reported CN-based catalysts, it was found that the FeOCl / NvCN photo-Fenton catalyst consumes 4-150 times less H2O2 than the previously reported CN-based photo-Fenton catalysts.

[0074] Figure 8 The heterostructure between FeOCl and NvCN was verified using TEM (scanning electron microscopy). Observations revealed that both NvCN and FeOCl exhibited a lamellar structure. The presence of these lamellar structures provided more active sites for the reaction, thus further promoting it. Furthermore, FeOCl and NvCN intertwined, forming a heterojunction. Figure 2 In the high-resolution scanning lens (HR-TEM) image of b, a close contact between FeOCl and NvCN can also be observed, with a lattice spacing of approximately 0.23 nm, which is related to the (021) surface of FeOCl. This close interfacial contact is expected to promote charge transfer processes in catalytic reactions.

[0075] Figure 9 The Z-type heterojunction structure between FeOCl / NvCN was analyzed. Figure 9 The results show that the conduction band (CB) and valence band (VB) of NvCN are located higher than those of FeOCl, and charge movement follows the type II heterojunction principle. Firstly, NvCN and FeOCl can generate photogenerated electrons under visible light excitation. These photogenerated electrons flow from the CB of NvCN to the CB of FeOCl, while photogenerated holes in the VB of FeOCl flow to the VB of NvCN, achieving separation of photogenerated carriers. Simultaneously, nitrogen vacancies act as trapping sites, accepting photogenerated electrons and promoting oxygen adsorption, thereby further promoting the separation of photogenerated carriers and increasing the generation of reactive oxygen species. Thus, the separation efficiency of photogenerated carriers in FeOCl / NvCN is improved. Furthermore, the CB of NvCN is higher than that of O2 / ·O2. - More negative (-0.33eV vs NHE), the accumulated e on CB - It can react with O2 to produce ·O2 - Because the VB of FeOCl is greater than that of OH -The ·OH group is not positive enough (1.99 eV vs NHE), and the formation of ·OH tends to occur through other pathways. On the one hand, some ·O2... - Free radicals continue to interact with H + The reaction produces ·OH. On the other hand, ·OH can also be formed in the Fenton reaction. The introduction of H₂O₂ can capture e-elements in the system. - It is then activated to generate ·OH. This process is accompanied by e - The consumption of H2O2, as an electron acceptor, inhibits the recombination of photogenerated carriers in the photo-Fenton system, which is beneficial to improving catalytic activity.

[0076] Table 1 shows that the H2O2 consumption of the FeOCl / NvCN photo-Fenton catalyst is 0.67%-25% of that of previously reported CN-based photo-Fenton catalysts. Typically, a higher catalyst dosage-normalized k comes at the cost of consuming a larger amount of antibiotic dosage-normalized H2O2. Based on these results, by rationally adjusting the catalyst and using ultra-low dosages of H2O2, higher catalytic performance for antibiotic degradation can be achieved, and it is expected to reduce the significant dependence on H2O2 in traditional photo-Fenton systems.

[0077] Table 1. Comparison of catalytic performance of FeOCl / NvCN materials with previously reported materials.

[0078]

[0079] The prior art cited in this invention is as follows:

[0080] [1]LNThi,TTTPhan,TNNgoc,NSMViswanath,HTTLe,L.Tran Thi,N.Tien-Trung,LTNguyen,DNNhiem,H.Tran Huu,V.Vo,Prussian Blue decorated g-C3N4–From novel synthesis to insight study on charge transfer strategy for improving visible-light driven photo-Fenton catalytic activity,J.AlloysCompd.916(2022)165331.https: / / doi.org / https: / / doi.org / 10.1016 / j.jallcom.2022.165331.

[0081] [2]L.Wang,Y.Zhu,D.Yang,L.Zhao,H.Ding,Z.Wang,The mixed marriage ofcopper and carbon ring-g-C3N4 nanosheet:A visible-light-driven heterogeneousFenton-like catalyst,Appl.Surf.Sci.488(2019)728-738.https: / / doi.org / https: / / doi.org / 10.1016 / j.apsusc.2019.05.288.

[0082] [3]J.Hou,D.Gao,X.Hu,L.Wang,Q.Guo,Rational construction of FeOOH / Cl-g-C3N4heterojunction for inducing Fenton catalysis and boosting visible-light-driven photocatalysis:Enhanced catalytic properties and mechanisminsight,J.Mol.Struct.1275(2023)134639.https: / / doi.org / https: / / doi.org / 10.1016 / j.molstruc.2022.134639.

[0083] [4]X.Zhang,B.Ren,X.Li,B.Liu,S.Wang,P.Yu,Y.Xu,G.Jiang,High-efficiencyremoval of tetracycline by carbon-bridge-doped g-C3N4 / Fe3O4 magneticheterogeneous catalyst through photo-Fenton process,J.Hazard.Mater.418(2021)126333.https: / / doi.org / https: / / doi.org / 10.1016 / j.jhazmat.2021.126333.

[0084] [5]X.Li,X.Zhang,S.Wang,P.Yu,Y.Xu,Y.Sun,Highly enhanced heterogeneousphoto-Fenton process for tetracycline degradation by Fe / SCN Fenton-likecatalyst,J.Environ.Manage.312(2022)114856.https: / / doi.org / https: / / doi.org / 10.1016 / j.jenvman.2022.114856.

[0085] [6]X.Zhang,B.Xu,S.Wang,X.Li,B.Liu,Y.Xu,P.Yu,Y.Sun,High-densitydispersion of CuN x sites for H2O2 activation toward enhanced Photo-Fentonperformance in antibiotic contaminant degradation,J.Hazard.Mater.423(2022)127039.https: / / doi.org / https: / / doi.org / 10.1016 / j.jhazmat.2021.127039.

[0086] [7]H.Zhao,C.Tian,J.Mei,S.Yang,P.K.Wong,Faster electron injection andhigher interface reactivity in g-C3N4 / Fe2O3 nanohybrid for efficient photo-Fenton-like activity toward antibiotics degradation,Environ.Res.195(2021)110842.https: / / doi.org / https: / / doi.org / 10.1016 / j.envres.2021.110842.

[0087] [8]C.Lu,J.Wang,D.Cao,F.Guo,X.Hao,D.Li,W.Shi,Synthesis of magneticallyrecyclable g-C3N4 / NiFe2O4 S-scheme heterojunction photocatalyst with promotedvisible-light-response photo-Fenton degradation of tetracycline,Mater.Res.Bull.158(2023)112064.https: / / doi.org / https: / / doi.org / 10.1016 / j.materresbull.2022.112064.

Claims

1. A method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient, and potassium-doped FeOCl / NvCN heterojunction, characterized in that, The method utilizes in-situ deposition to prepare photo-Fenton catalysts with FeOCl / NvCN heterojunctions, and includes the following steps: Step 1: Dissolve a certain amount of KOH in deionized water to obtain a deionized water KOH solution with a mass-volume concentration of 0.008 ~ 0.01 g / mL; Step 2: Add melamine powder to the solution described in Step 1 and stir to make the solution uniform. The mass ratio of KOH to melamine is (0.35~3.5):

100. Step 3: Place the mixed solution of KOH and melamine obtained in Step 2 in an oven and dry for 6-12 hours to obtain powder; Step 4: Grind the dried powder thoroughly, place it in a muffle furnace and heat it to 600ºC for 2-3 hours, with a heating rate of 3-5ºC per minute, to obtain NvCN powder; Step 5: Add deionized water to the crucible, then add FeCl3·6H2O powder to the crucible to obtain ferric chloride solution, and then add NvCN obtained in step 4 to the solution to obtain a mixed liquid; Step 6: Sonicate the mixture to ensure thorough mixing; Step 7: After the crucible is thoroughly dried in an oven, the powder is obtained and then ground to obtain fine powder. Step 8: Place the obtained fine powder in a muffle furnace and heat it to 250ºC for calcination for 2-3 hours at a heating rate of 3-5ºC per minute; to obtain composite material powder with FeOCl / NvCN heterostructure; Step 9: Wash the composite material with FeOCl / NvCN heterojunction repeatedly with acetone and deionized water to remove residual ferric ions, and then dry it to obtain a photo-Fenton catalyst with low H2O2 consumption, nitrogen defects and potassium doped FeOCl / NvCN heterojunction. The mass ratio of FeCl3·6H2O to NvCN in the catalyst prepared by the method is 0.4~2.0; The catalyst is constructed by doping potassium and introducing nitrogen vacancies in g-C3N4 and combining it with FeOCl to form a FeOCl / NvCN heterojunction. The FeOCl / NvCN heterojunction is a Z-type heterojunction.

2. The method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen defects, and potassium doped FeOCl / NvCN heterojunction as described in claim 1, characterized in that, In step 2, the mass ratio of KOH to melamine is 1:

100.

3. The method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction according to claim 1, characterized in that, Stir for 15-20 minutes in step 2 to make the solution homogeneous.

4. The method for preparing a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient and potassium-doped FeOCl / NvCN heterojunction according to claim 1, characterized in that, Dry in an oven at a drying temperature of 70~85ºC for 6~10 hours in step 3.

5. The method for preparing the photocatalyst with low H2O2 consumption, nitrogen defects, and potassium doped FeOCl / NvCN heterojunction according to claim 1, characterized in that, In step 6, ultrasonic treatment is performed for 1-3 hours to ensure thorough mixing.

6. The application of a photo-Fenton catalyst with low H2O2 consumption, nitrogen-deficient, and potassium-doped FeOCl / NvCN heterojunction, characterized in that... This catalyst is used for the degradation of tetracycline hydrochloride (TC). The FeOCl / NvCN heterojunction photo-Fenton catalyst is added to tetracycline antibiotic wastewater at a dosage of 0.025 g / L to 0.20 g / L. The catalyst is first magnetically stirred in a dark room at a rate of 450 r / min to 600 r / min until adsorption and desorption equilibrium is reached. Then, photo-Fenton catalytic oxidation is carried out under the irradiation of a xenon lamp with a power of 300 W to 350 W. The FeOCl / NvCN heterojunction is a Z-type heterojunction.

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