An In2O3 / ZnWO4 composite photocatalytic material, its preparation method and application

Abstract

The present invention relates to an In2O3 / ZnWO4 composite photocatalytic material, its preparation method and application, and belongs to the technical field of photocatalyst materials. An In2O3 / ZnWO4 composite photocatalytic material is prepared by the following preparation method: sintering MIL-68(In) and ZnWO4 to obtain the In2O3 / ZnWO4 composite photocatalytic material, wherein the sintering time is 1 to 3 h, the sintering temperature is 450 to 550 °C, and the mass ratio of MIL-68(In) to ZnWO4 is (0.5 to 5):1. The In2O3 / ZnWO4 composite photocatalytic material of the present invention can effectively improve the degradation efficiency of photocatalytic degradation of high-concentration tetracycline hydrochloride aqueous solution and has excellent long-term stability.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst materials, and more specifically, to an In2O3 / ZnWO4 composite photocatalytic material, a preparation method thereof, and an application thereof. Background Art

[0002] As natural or synthetic compounds with antibacterial or bactericidal activities, antibiotics can be used to treat and prevent various diseases caused by bacterial infections and are widely used in the medical and livestock industries. According to the mechanism of action, antibiotics mainly include tetracyclines (TCs), aminoglycosides (AGs), β-lactams, sulfonamides (SAs), fluoroquinolones (FQs), macrolides (MLs), etc. However, neither humans nor animals can completely metabolize antibiotics. Antibiotics are partially metabolized, then excreted through urine and feces, and then enter the environment through incomplete treatment in wastewater treatment plants. Currently, the antibiotic pollution in water bodies mainly comes from the pharmaceutical industry, livestock farming, aquaculture, etc. The concentration ranges of various antibiotics in water are from ng / L to mg / L. Within the influence range of urban wastewater treatment plants, they are usually between 1 ng / L and >1 mg / L, while industrial wastewater, such as pharmaceutical and livestock wastewater, may contain higher concentrations, up to 100 mg / L. Different from other traditional organic pollutants such as dyes and pesticides, the concentration of antibiotics is mainly relatively low, but they are highly toxic. The accumulation of antibiotics released into the environment at a certain concentration will affect the dynamic balance of the microbial community. This will lead to the generation of drug-resistant bacteria in humans and animals and even cause gene mutations. The treatment cost of antibiotic wastewater is high, and the wastewater composition is complex, which is a kind of refractory organic wastewater. Tetracycline is one of the most widely used and largest consumption antibiotics, and it is of great significance to seek an efficient method for removing tetracycline.

[0003] Photocatalytic oxidation technology has the characteristics of being reusable and green and is considered to be one of the most effective methods for treating antibiotic wastewater pollution. Different from traditional sewage treatment technologies, photocatalytic technology converts solar energy into chemical energy. The photo-generated electrons and holes generated during the photocatalytic process can decompose and mineralize sewage into carbon dioxide and water, which is an environmentally friendly technology.

[0004] Chinese Patent CN118513060A discloses a preparation method and application of a composite zinc tungstate / bismuth oxychloride heterojunction photocatalyst. The preparation method of the composite zinc tungstate / bismuth oxychloride heterojunction photocatalyst is to fully mix sodium chloride and bismuth nitrate and then carry out a hydrothermal reaction with ZnWO4 together; after the reaction is completed, it is cooled to room temperature, washed, dried and ground to obtain the composite photocatalyst, which is a stacked body of petal-shaped nanosheets and nanoparticles. 20 mg of the catalyst sample is dispersed in 50 mL of an aqueous solution of tetracycline hydrochloride with a concentration of 20 mg / L, and stirred in the dark for 30 min to reach the adsorption-desorption equilibrium state. By using a UV-visible spectrophotometer (UV-vis) to measure the photocatalytic degradation efficiency of tetracycline hydrochloride, the degradation rate of tetracycline hydrochloride under 60 min of irradiation is less than 65%. However, the photocatalytic degradation efficiency of tetracycline needs to be further improved. Summary of the Invention

[0005] The object of the present invention is to overcome the defects and deficiencies that the degradation efficiency of the existing photocatalyst for degrading tetracycline hydrochloride needs to be further improved, and to provide an In2O3 / ZnWO4 composite photocatalytic material, which can effectively improve the degradation efficiency of its photocatalytic degradation of high-concentration aqueous solutions of tetracycline hydrochloride.

[0006] The above object of the present invention is achieved by the following technical solutions:

[0007] An In2O3 / ZnWO4 composite photocatalytic material is prepared by the following preparation method: sinter MIL-68(In) and ZnWO4 to obtain the In2O3 / ZnWO4 composite photocatalytic material, wherein the sintering time is 1-3 h, the sintering temperature is 450-550 °C, and the mass ratio of MIL-68(In) to ZnWO4 is (0.5-5):1.

[0008] MIL-68(In) is a metal-organic framework (MOF) material. MIL-68(In) can be obtained commercially or prepared by oneself.

[0009] The present invention uses MIL-68(In) as a precursor to prepare the In2O3 / ZnWO4 composite photocatalytic material because the highly ordered pores and uniformly distributed metal sites of the MIL-68(In) metal-organic framework (MOF) material can be transformed into In2O3 to form a special morphology of a porous nanostructure. This helps to increase the specific surface area of the photocatalyst, enhance light absorption and the diffusion performance of reactants. The metal ions in the MOF material are uniformly transformed into In2O3 during the pyrolysis process, making the catalyst have highly dispersed active sites, which is beneficial to the improvement of the reaction efficiency.

[0010] Moreover, In2O3 derived from metal-organic frameworks (MOF) generates a large number of oxygen vacancies (OVs), which is conducive to the separation of photoinduced electron-hole pairs. In2O3 with OVs has more molecular oxygen adsorption and activation sites, which leads to the generation of superoxide radicals that can be converted into singlet oxygen through a charge transfer process. The electrophilic reactive oxygen species (ROS) called singlet oxygen can initiate an attack on the electron-rich groups (such as benzene rings) present in tetracycline molecules, thereby improving the overall degradation efficiency.

[0011] Zinc tungstate (ZnWO4) has a band gap of 3.5 eV, which matches the band structure of In2O3. The composite photocatalytic material of the present invention uses a sintering method to derive MIL-68(In) into In2O3 and composite it with ZnWO4, successfully constructing an In2O3 / ZnWO4 heterojunction In2O3 / ZnWO4 composite photocatalytic material with a suitable band gap, which is conducive to promoting the separation and migration rate of photogenerated electrons and holes, reducing the recombination rate of photogenerated electrons and holes, thereby improving the activity and stability of the catalyst. It improves the degradation rate of high-concentration tetracycline hydrochloride antibiotic organic pollutants under visible light irradiation.

[0012] In a specific embodiment, the sintering time can be 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0013] In a specific embodiment, the sintering temperature can be 450 °C, 480 °C, 500 °C, 520 °C, or 550 °C.

[0014] In a specific embodiment, the mass ratio of MIL-68(In) to ZnWO4 can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5.

[0015] Preferably, the mass ratio of MIL-68(In) to ZnWO4 is (3-4):1.

[0016] Preferably, before the sintering treatment, it further includes sintering MIL-68(In) and ZnWO4 at 100-130 °C for 1-3 hours. The sintering temperature can be 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, or 130 °C. The sintering time can be 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0017] MIL-68(In) has a one-dimensional pore structure and a large specific surface area. The porous environment provides sufficient adsorption sites for water molecules, and it may adsorb water even at low humidity. In the present invention, by sintering at a lower temperature of 100-130 °C for 1-3 hours first, the water in the MIL-68(In) sample powder can be removed.

[0018] Preferably, the preparation method of MIL-68(In) comprises the following steps: mixing indium nitrate, terephthalic acid and N,N-dimethylformamide, and reacting at a reaction temperature of 110-130°C for 1-3 h to obtain MIL-68(In).

[0019] The reaction conditions in the preparation method of MIL-68(In) will directly affect the final size of MIL-68(In).

[0020] ZnWO4 can be obtained commercially or prepared by oneself. Generally, the size of commercially available ZnWO4 is larger.

[0021] Preferably, the ZnWO4 has a nanorod-like structure, and the length of the nanorods is about 100-300 nm.

[0022] Preferably, the preparation method of ZnWO4 comprises the following steps: mixing zinc nitrate and sodium tungstate, and reacting at a reaction temperature of 180-200°C for 20-24 h to obtain ZnWO4.

[0023] The present invention also protects the application of the In2O3 / ZnWO4 composite photocatalytic material described in any one of the above in the photocatalytic degradation of antibiotics in water bodies.

[0024] Preferably, the antibiotic is tetracycline hydrochloride.

[0025] Preferably, the concentration of tetracycline hydrochloride in the water body is 20 mg / L, and the addition amount of the In2O3 / ZnWO4 composite photocatalytic material in water is 10-20 mg / 50 mL.

[0026] Preferably, the light wavelength of the photocatalysis is 420 nm.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] The present invention provides an In2O3 / ZnWO4 composite photocatalytic material. By using the sintering method, MIL-68(In) is derivatized into In2O3 and compounded with ZnWO4, and an In2O3 / ZnWO4 heterojunction In2O3 / ZnWO4 composite photocatalytic material with a suitable band gap is successfully constructed, which is beneficial to promoting the separation and migration rate of photogenerated electrons and holes, reducing the recombination rate of photogenerated electrons and holes, thereby improving the activity and stability of the catalyst, and improving the degradation rate of the photocatalyst for high-concentration tetracycline hydrochloride antibiotic organic pollutants under visible light irradiation. And it has excellent long-term stability. Description of the Drawings

[0029] Figure 1 Among them, (a) is the SEM diagram of Comparative Example 1. Figure 1Among them, (b) is the enlarged SEM image of Comparative Example 1. Figure 1 Among them, (c) is the SEM image of Comparative Example 2. Figure 1 Among them, (d) is the enlarged SEM image of Comparative Example 2. Figure 1 Among them, (e) is the SEM image of Example 3. Figure 1 Among them, (f) is the enlarged SEM image of Example 3.

[0030] Figure 2 It is the XRD pattern fitted for MIL-68(In) and the experimentally measured XRD pattern.

[0031] Figure 3 XRD patterns and partial enlarged views of Examples 1 to 4, Comparative Example 1 and Comparative Example 2.

[0032] Figure 4 It is the photocatalytic degradation curves of the catalysts of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 for tetracycline hydrochloride at a dosage of 20 mg.

[0033] Figure 5 It is the pseudo-first-order reaction kinetic diagram of the degradation process of tetracycline hydrochloride by the catalysts of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at a dosage of 20 mg.

[0034] Figure 6 It is the photocatalytic degradation curves of the catalysts of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 for tetracycline hydrochloride at a dosage of 10 mg.

[0035] Figure 7 It is the pseudo-first-order reaction kinetic diagram of the degradation process of tetracycline hydrochloride by the catalysts of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at a dosage of 10 mg.

[0036] Figure 8 It is the XRD comparison diagram before and after the reaction of Example 3. Detailed implementation manners

[0037] The present invention will be further described below in conjunction with the detailed implementation manners, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventionally purchased raw material reagents.

[0038] Example 1

[0039] An In2O3 / ZnWO4 composite photocatalytic material is prepared by the following preparation method:

[0040] (1) Preparation of MIL-68(In): Dissolve 600 mg of In(NO3)3·3H2O and 600 mg of terephthalic acid (H2BDC) in 100 mL of N,N-dimethylformamide (DMF), and stir for 10 min to form a clear solution. Then place the mixture in an oil bath and heat at 120 °C for 2 h. After cooling to room temperature, collect the white precipitate by centrifugation and wash it several times with ethanol, and dry it at 60 °C for 12 h. The white powder can be collected to obtain MIL-68(In).

[0041] (2) Preparation of ZnWO4: Dissolve 3 mmol of Zn(NO3)2·6H2O in 30 mL of deionized water to form solution A, and dissolve 3 mmol of NaWO4·2H2O in 25 mL of deionized water to form solution B. Stir for 10 min to completely dissolve it. Then slowly add solution B dropwise to solution A, and maintain the pH of the solution at 8 by using an ammonia aqueous solution, and stir for 30 min. Subsequently, heat the resulting mixture in an 80 mL autoclave at 180 °C for 24 h. After the hydrothermal reaction is completed, let the autoclave cool naturally to room temperature, collect the obtained product by centrifugation and wash it several times with deionized water and ethanol. The obtained product is dried at 60 °C for 12 h, and the white powder can be collected to obtain ZnWO4.

[0042] (3) Preparation of In2O3 / ZnWO4 composite

[0043] Mix 0.1 g of MIL-68(In) and 0.1 g of ZnWO4 evenly by grinding. Then place the mixed powder in a tube furnace and heat it to 120 °C at a rate of 5 °C / min for 2 h, and then heat it to 500 °C and keep sintering for 2 h to obtain the In2O3 / ZnWO4 composite (abbreviation IZ-1);

[0044] Among them, the mass ratio of MIL-68(In) to ZnWO4 is 1:1.

[0045] Example 2

[0046] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 1 in that:

[0047] The mass ratio of MIL-68(In) to ZnWO4 is 2:1. That is, 0.2 g of MIL-68(In) and 0.1 g of ZnWO4 are used in step (3).

[0048] The obtained material is abbreviated as IZ-2.

[0049] The rest is the same as in Example 1 and will not be elaborated here.

[0050] Example 3

[0051] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 1 in that:

[0052] The mass ratio of MIL-68(In) to ZnWO4 is 3:1. That is, 0.3 g of MIL-68(In) and 0.1 g of ZnWO4 are used in step (3).

[0053] The obtained material is abbreviated as IZ-3.

[0054] The rest is the same as in Example 1 and will not be elaborated here.

[0055] Example 4

[0056] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 1 in that:

[0057] The mass ratio of MIL-68(In) to ZnWO4 is 4:1. That is, 0.4 g of MIL-68(In) and 0.1 g of ZnWO4 are used in step (3).

[0058] The obtained material is abbreviated as IZ-4.

[0059] The rest is the same as in Example 1 and will not be elaborated here.

[0060] Example 5

[0061] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 3 in that:

[0062] The mixed powder of MIL-68(In) and ZnWO4 is heated in a tubular furnace at a rate of 5 °C / min to 120 °C and sintered for 2 hours, then heated to 450 °C and kept sintered for 2 hours.

[0063] The rest is the same as in Example 3 and will not be elaborated here.

[0064] Example 6

[0065] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 3 in that:

[0066] The mixed powder of MIL-68(In) and ZnWO4 is heated in a tubular furnace at a rate of 5 °C / min to 120 °C and sintered for 2 hours, then heated to 550 °C and kept sintered for 2 hours.

[0067] The rest is the same as in Example 3 and will not be elaborated here.

[0068] Example 7

[0069] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 3 in that:

[0070] The mixed powder of MIL-68(In) and ZnWO4 was heated in a tube furnace to 120 °C at a rate of 5 °C / min and sintered for 2 hours, then heated to 500 °C and kept sintering for 1 hour.

[0071] The rest is the same as Example 3 and will not be elaborated here.

[0072] Example 8

[0073] An In2O3 / ZnWO4 composite photocatalytic material, different from the preparation method of Example 3 in that:

[0074] The mixed powder of MIL-68(In) and ZnWO4 was heated in a tube furnace to 120 °C at a rate of 5 °C / min and sintered for 2 hours, then heated to 500 °C and kept sintering for 3 hours.

[0075] The rest is the same as Example 3 and will not be elaborated here.

[0076] Comparative Example 1

[0077] A preparation method of a ZnWO4 catalyst is the same as the preparation method of ZnWO4 in Example 1 and will not be elaborated here.

[0078] Comparative Example 2

[0079] A preparation method of an In2O3 catalyst includes the following steps:

[0080] (1) The preparation of MIL-68(In) is the same as that in Example 1.

[0081] (2) Preparation of In2O3: Place a certain amount of MIL-68(In) powder in a tube furnace, heat it to 120 °C at a rate of 5 °C / min and sinter for 2 hours, then heat it to 500 °C and keep sintering for 2 hours, and collect the pale yellow powder to obtain In2O3.

[0082] Comparative Example 3

[0083] A preparation method of a ZnWO4 / BiOCl catalyst includes the following steps:

[0084] (1) Place 2 mmol of zinc nitrate hexahydrate and sodium tungstate dihydrate in a 50 ml beaker, add 25 ml of deionized water, and place the beaker on a magnetic stirrer and stir for 30 minutes. Then transfer the obtained homogeneous solution to a 50 ml stainless steel autoclave with a PTFE liner, and place it in an oven and react at 180 °C for 15 h. After the reaction is completed, cool to room temperature, take out the reactant, centrifuge to collect the obtained precipitate, wash it alternately with deionized water and absolute ethanol 3 times, heat it at 60 °C for 12 h, grind the dried reactant to obtain ZnWO4.

[0085] (2) Dissolve 2 mmol of bismuth nitrate pentahydrate in 25 ml of ethylene glycol, dissolve 2 mmol of sodium chloride in 25 ml of deionized water, place them on a magnetic stirrer and stir evenly respectively. Under continuous stirring, drop the sodium chloride aqueous solution into the bismuth nitrate pentahydrate solution, stir the mixed solution for 30 minutes to make it evenly distributed, then add 0.058 g of the ZnWO4 material prepared in step (1) into it, continue to stir for 3 h, and then transfer the obtained evenly mixed solution to a 100 ml stainless steel autoclave, place it in an oven and react at 150 °C for 10 h. After the reaction is completed, cool to room temperature, centrifuge the obtained precipitate, and wash it alternately with deionized water and absolute ethanol 3 times, heat it at 60 °C for 12 h, grind the dried reactant to obtain the ZnWO4 / BiOCl heterojunction photocatalyst material.

[0086] Comparative Example 4

[0087] A preparation method of an In2O3 catalyst, comprising the following steps:

[0088] (1) The preparation of MIL-68(In) is the same as that in Example 1.

[0089] (2) Preparation of In2O3: Place a certain amount of MIL-68(In) powder in a tubular furnace, heat it to 120 °C at a rate of 5 °C / min and sinter for 2 hours, then heat it to 400 °C and keep sintering for 2 hours, and collect the pale yellow powder to obtain In2O3.

[0090] Comparative Example 5

[0091] A preparation method of an In2O3 catalyst, comprising the following steps:

[0092] (1) The preparation of MIL-68(In) is the same as that in Example 1.

[0093] (2) Preparation of In2O3: Place a certain amount of MIL-68(In) powder in a tubular furnace, heat it to 120 °C at a rate of 5 °C / min and sinter for 2 hours, then heat it to 600 °C and keep sintering for 2 hours, and collect the pale yellow powder to obtain In2O3.

[0094] Result detection

[0095] The catalysts prepared in Examples 1-8 and Comparative Examples 1-5 were respectively subjected to structural characterization and performance testing.

[0096] (1)SEM

[0097] The morphological characteristics of the materials of Example 3, Comparative Example 1, and Comparative Example 2 were investigated by scanning electron microscopy (SEM), as Figure 1 shown. Figure 1 In (a) is the SEM image of Comparative Example 1. Figure 1 In (b) is the enlarged SEM image of Comparative Example 1. Figure 1 In (c) is the SEM image of Comparative Example 2. Figure 1 In (d) is the enlarged SEM image of Comparative Example 2. Figure 1 In (e) is the SEM image of Example 3. Figure 1 In (f) is the enlarged SEM image of Example 3. Among them, the ZnWO4 in Comparative Example 1 has a rod-like structure, and the length of the rod is about 100-300 nm. The In2O3 in Comparative Example 2 has a granular structure of 50-100 nm. And Example 3 shows a mixed structure of In2O3 nanoparticles and ZnWO4 nanorods.

[0098] (2)XRD test

[0099] The crystal structures of MIL-68(In) and Examples 1-4, Comparative Example 1, and Comparative Example 2 were analyzed by X-ray diffraction (XRD), as Figure 2 , Figure 3 shown. Figure 2 The results show that the XRD pattern obtained from the synthesized MIL-68(In) is basically consistent with the fitted pattern, indicating that the sample was successfully synthesized. Figure 3 The peak positions of the characteristic diffraction peaks of In2O3 and ZnWO4 in are basically consistent with the standard cards (PDF#71-2195) and (PDF#15-0774) respectively, and no characteristic peaks of other substances were observed, indicating that their purity is very high, indicating that the sample was successfully synthesized. Figure 3 From the XRD patterns and partial enlarged views of the In2O3 / ZnWO4 composite materials with different mass ratios in, it can be seen that the strongest characteristic peaks of In2O3 and ZnWO4 coincide. As the content of ZnWO4 decreases, its characteristic peak at 36.312° gradually weakens, while the characteristic peak of In2O3 at 35.462° gradually strengthens. From Figure 3 it can be seen that after the combination of In2O3 and ZnWO4, the characteristic peaks of both In2O3 and ZnWO4 exist in the composite material, proving the successful synthesis of the composite.

[0100] (3)Photocatalytic degradation test of tetracycline hydrochloride

[0101] Specific test method: Using a 420 nm LED light source, photocatalytic activity tests were carried out with tetracycline hydrochloride (TC-HCl) as the target pollutant. 10 mg and 20 mg of the material samples of Examples 1 to 8 and Comparative Examples 1 to 5 were respectively dispersed in 50 mL of a TC-HCl aqueous solution with a concentration of 20 mg / L and stirred in the dark for 30 min to enable the obtained samples and TC-HCl to reach adsorption-desorption equilibrium. Then, visible light was turned on, and 4 mL of the mixed solution was collected every 10 min. After removing the photocatalyst powder by centrifugation, the absorbance (357 nm) of the supernatant tetracycline hydrochloride was measured using a UV-visible spectrophotometer (UV-vis) and compared with the absorbance of the initial solution, thereby obtaining the degradation efficiency of the photocatalyst.

[0102] The specific detection results of the degradation of tetracycline hydrochloride by each sample after 30 minutes and 60 minutes of reaction are shown in Table 1 below.

[0103] Table 1

[0104]

[0105] As can be seen from the above results, the single ZnWO4 and In2O3 in Comparative Examples 1 and 2 had low degradation rates for tetracycline hydrochloride. When In2O3 and ZnWO4 formed a composite material, the photocatalytic activity was significantly improved. For a high-concentration tetracycline hydrochloride aqueous solution with a concentration of 20 mg / L, when the dosage of the catalyst was 10 mg, the degradation efficiency of tetracycline hydrochloride could reach 56.16% - 72.57%, and when the dosage of the catalyst was 20 mg, the degradation efficiency of tetracycline hydrochloride could reach 73.65% - 79.33%. This shows that the composite material formed by In2O3 and ZnWO4 has better visible light absorption ability and promotes the separation efficiency of photo-generated carriers, thereby improving the photocatalytic performance. Figure 4 、 Figure 6 The test results show that the increase in the content of In2O3 improves the photocatalytic degradation performance of the composite catalyst for tetracycline hydrochloride, but when the content of In2O3 exceeds a certain amount, it will cause agglomeration of In2O3 nanoparticles, affecting its photocatalytic performance.

[0106] As can be seen from Examples 3 and 5 to 8, when MIL-68(In) and ZnWO4 were sintered under the conditions of a sintering time of 1 - 3 h and a sintering temperature of 450 - 550 °C, the obtained catalysts all had more excellent degradation efficiency for tetracycline hydrochloride.

[0107] The first-order kinetic equation was used to fit the experimental data to quantitatively understand the degradation performance of the photocatalyst for tetracycline hydrochloride. As Figure 5 、 Figure 7 shown, the results confirmed that the reaction rate constants of each example were all above k = 0.012 min -1 , much higher than those of ZnWO4 and In2O3 in Comparative Example 1 and Comparative Example 2. Among them, IZ-3 had the highest reaction rate constants (k = 0.01954 min -1 and k = 0.01885 min -1 ), which were 3.32 times and 8.69 times those of pure ZnWO4 (k = 0.00589 min -1 and k = 0.00217 min -1 ) respectively, and 1.43 times and 3.91 times those of In2O3 (k = 0.01368 min -1 and k = 0.00482 min -1 ), indicating that the composite photocatalyst of the present invention has great photocatalytic activity for photocatalytic degradation of tetracycline hydrochloride.

[0108] (4) Stability test: The degradation stability of the catalyst in Example 3 was evaluated, and the structural changes of Example 3 before and after the reaction were evaluated by X-ray diffraction (XRD). From Figure 8 the test results, it was shown that compared with the catalyst before the reaction, there was no obvious change in the crystal structure of Example 3 after use, only the peak intensity decreased slightly. This reflected the excellent stability of the IZ-3 composite material.

[0109] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made on the basis of the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. Application of an In2O3 / ZnWO4 composite photocatalytic material in photocatalytic degradation of tetracycline hydrochloride in water, characterized in that, The In2O3 / ZnWO4 composite photocatalytic material is prepared by the following preparation method: sinter MIL-68(In) and ZnWO4 to obtain the In2O3 / ZnWO4 composite photocatalytic material, wherein the sintering time is 1 to 3 h, the sintering temperature is 480 to 520 °C, and the mass ratio of MIL-68(In) to ZnWO4 is (2.5 to 3):

1.

2. The application according to claim 1, characterized in that, Before the sintering treatment, it also includes sintering MIL-68(In) and ZnWO4 at 100 to 130 °C for 1 to 3 hours first.

3. The application according to claim 1, wherein The preparation method of the MIL-68(In) includes the following steps: mix indium nitrate, terephthalic acid and N,N-dimethylformamide, and react at a reaction temperature of 110 °C to 130 °C for 1 to 3 h to obtain MIL-68(In).

4. The application according to claim 1, wherein The preparation method of the ZnWO4 includes the following steps: mix zinc nitrate and sodium tungstate, and react at a reaction temperature of 180 to 200 °C for 20 to 24 h to obtain ZnWO4.

5. The application according to claim 1, wherein The concentration of tetracycline hydrochloride in the water body is 20 mg / L, and the addition amount of the In2O3 / ZnWO4 composite photocatalytic material in water is 10 to 20 mg / 50 mL.

6. The application according to claim 1, characterized in that, The light wavelength of the photocatalysis is 420 nm.

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