Preparation of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane and application method thereof

Abstract

The application provides a preparation method and application of an SrTiO3.Al-MgO / PSF-PVDF photocatalytic membrane, relates to a preparation method and application of a photocatalytic membrane, and utilizes a high-temperature solid-phase method and a non-in-situ technology to synthesize SrTiO3.Al-MgO photocatalyst powder; different amounts of SrTiO3.Al-MgO photocatalyst powder are fused into a PSF-PVDF base liquid system, the system comprises PSF, PVDF, LiCl, DMAc and EGME, and finally, an SrTiO3.Al-MgO / PSF-PVDF composite photocatalytic membrane is prepared. Under the irradiation of visible light, the photocatalytic membrane degrades organic pollutants in wastewater, improves the removal of pollutants in high efficiency, pollution resistance, and the advantages in energy saving and environmental protection. The maintenance cost and energy consumption of the system are reduced, the development of environmental purification technology is promoted to intelligence and greenness, and the photocatalytic membrane has wide application potential in the field of wastewater degradation.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a photocatalytic membrane, and particularly to a method for preparing and applying a SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane. Background Technology

[0002] In addition to inorganic pollutants, water bodies contain a large amount of organic pollutants. These pollutants affect ecosystems and harm human health through toxicity and reduction of dissolved oxygen. Specific organic pollutants refer to organic compounds that are highly toxic, cumulative, and difficult to degrade, and are listed as priority pollutants. They are numerous in variety but present in low concentrations. Organic pollutants are organic compounds that cause environmental pollution and have harmful effects on ecosystems. They can be divided into two main categories: natural organic pollutants and artificially synthesized organic pollutants. The former are mainly produced by the metabolic activities of organisms and other biochemical processes; such as chlortetracycline and ethyl carbamate. The latter are produced with the rise of modern synthetic chemical industry; such as plastics, synthetic fibers, dyes, coatings, pesticides, food additives, and pharmaceuticals. Among organic pollutants, antibiotics pose the most serious threat to human health. For example, antibiotics enter the stomach through the mouth, are absorbed into the bloodstream through the intestines, and are transported to various cells in the body. Only drugs that reach the lesion site can kill pathogens. Drugs in other tissues not only do not kill bacteria, but their metabolic products are also excreted through the liver and kidneys, which can damage organs such as the liver and kidneys. For example, tetracycline and erythromycin need to be metabolized in the liver.

[0003] Therefore, to ensure human health and the aspiration for a green home, the degradation of antibiotic-related organic pollutants has become an important task. Photocatalytic degradation technology, through the activation of photocatalysts by visible light irradiation, can degrade organic pollutants in antibiotics into non-toxic products, becoming a popular method for addressing the environmental pollution and health hazards caused by antibiotic abuse. Photocatalytic degradation technology is widely used for the treatment of organic pollutants due to its clean energy, wide applicability, and lack of secondary pollution. However, traditional photocatalysts are usually in powder form, which are small in size, easily deactivated, have poor stability, and are difficult to separate and recover. Photocatalytic membranes are a new type of highly efficient photocatalytic material applicable to continuous processes. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane. This method is based on a photocatalytic-membrane separation cycle system for degrading organic pollutants in wastewater. Under visible light irradiation, this method degrades organic pollutants in wastewater, improving the efficiency and anti-pollution properties of pollutant removal, as well as offering advantages in energy conservation and environmental protection. It reduces system maintenance costs and energy consumption, promoting the intelligent and green development of environmental purification technology.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for preparing a SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane, the method comprising the following steps:

[0007] S1: Preparation of MgO photocatalyst nanoparticles via thermal decomposition:

[0008] Mg(OH)2 was used as a precursor and decomposed by high-temperature calcination to obtain MgO, which was then collected by grinding after cooling.

[0009] S2: Preparation of SrTiO3 photocatalyst nanoparticles via solid-state reaction method:

[0010] Strontium carbonate (SrCO3) and titanium dioxide (TiO2) are mixed and ground in a ball mill to ensure uniform distribution of the reactants. The mixed powder is then heated to 700-900℃ to remove excess moisture and decompose the carbonates in the powder. Subsequently, the pre-calcined powder is further sintered at 1300-1500℃ to form SrTiO3 with a complete crystalline phase. After slow cooling, the powder is ground and collected.

[0011] S3: Preparation of SrTiO3·Al photocatalyst nanoparticles using a hydrothermal method:

[0012] SrCl2, TiCl4, and AlCl3 were dissolved in an aqueous solvent to form a mixed solution. The pH of the solution was adjusted to be greater than 13. The solution was then transferred to an autoclave and subjected to a hydrothermal reaction at 150-250℃ for 12-48 hours. During the reaction, SrTiO3 with a perovskite structure gradually formed, and aluminum doping was incorporated into the crystal lattice. After cooling, the product was removed, washed, dried, and further heat-treated to improve crystallinity.

[0013] S4: Preparation of SrTiO3·Al-MgO photocatalyst nanoparticles using an in-situ method:

[0014] SrTiO3·Al powder was impregnated in an aqueous solution of Mg(OH)2, sonicated for 120 min, centrifuged, dried, and collected. The dried mixture was then placed in a tube furnace for calcination under the following conditions: temperature 600℃, calcination time 150 min, and flow rate 50 mL·min. -1 Argon gas was used to prepare SrTiO3·Al-MgO photocatalyst nanoparticles.

[0015] S5: Preparation of MgO / PSF-PVDF, SrTiO3 / PSF-PVDF, SrTiO3·Al / PSF-PVDF, and SrTiO3·Al-MgO / PSF-PVDF photocatalytic films:

[0016] The substrate solution for the photocatalytic membrane was prepared by adding MgO, SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO photocatalyst particles to a mixture of polysulfone (PSF), polyvinylidene fluoride (PVDF), lithium chloride (LiCl), N,N-dimethylacetamide (DMAC), and ethylene glycol dimethyl ether (EGME). After stirring and mixing thoroughly for 12 hours, the mixture was filtered and degassed using a vacuum pump. The degassed solution was then evenly spread onto a glass plate using a scraper to form a rectangular shape. The glass plate was then immersed in a deionized water bath for 24 hours to prepare MgO / PSF-PVDF, SrTiO3 / PSF-PVDF, SrTiO3·Al / PSF-PVDF, and SrTiO3·Al-MgO / PSF-PVDF photocatalytic membranes, respectively.

[0017] A method for applying a SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane, the method comprising a photocatalytic membrane separation and degradation organic pollutant recycling system, the system comprising a storage tank, a bypass pipe, a gear pump, a pressure gauge, a flow meter, a regulating valve, a xenon lamp, and a photocatalytic membrane degradation device;

[0018] The application process is as follows:

[0019] Organic wastewater is placed in the storage tank. The pressure gauge and flow meter are adjusted. The SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is cut into a circle with a radius of 3cm and placed in the photocatalytic membrane degradation device and fixed. A 300W xenon lamp is installed above the center of the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincides with the center of the photocatalytic membrane degradation device. The middle part of this photocatalytic membrane degradation device is a circular transparent quartz glass to provide visible light for the working process of the photocatalytic membrane degradation device. The gear pump is turned on, and the rotation of the gear pump generates negative pressure, which draws the organic wastewater in the storage tank into the circulation system. Part of the organic wastewater flows back to the storage tank through the bypass pipe, and part of it enters the photocatalytic membrane degradation device through the pressure gauge. After the organic wastewater flows out of the photocatalytic membrane degradation device, it flows through the pressure regulating valve and flow meter, and finally returns to the storage tank. The circulation treatment takes 150 minutes.

[0020] The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is described above, wherein the photocatalytic membrane degradation device is provided with a photocatalytic membrane layer.

[0021] The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is described above, wherein the pressure value of the pressure gauge is 0.2 MPa.

[0022] The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane, wherein the flow rate count value is 40 mL·min -1 .

[0023] The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is described above, wherein the initial concentration of organic pollutants in the wastewater is 5-15 mg / L; the organic pollutants are organic compounds.

[0024] The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane, wherein the organic compound is chlortetracycline, streptomycin, or gentamicin.

[0025] The beneficial effects of this invention are:

[0026] 1. The photocatalytic membrane prepared by this invention provides an efficient, stable, environmentally friendly, and economical solution for degrading organic pollutants. It not only improves pollutant removal efficiency but also reduces catalyst loss and recovery difficulty, enabling long-term use in various environments. Furthermore, photocatalytic membrane technology can be combined with other purification technologies to form a more comprehensive pollution control system, exhibiting strong adaptability and energy efficiency.

[0027] 2. This invention uses photocatalysis-membrane separation to degrade organic pollutants. Under visible light irradiation, the photocatalyst degrades organic pollutants in wastewater into small molecule products such as carbon dioxide and water.

[0028] 3. This invention creatively provides a method for degrading organic pollutants using photocatalysis-membrane separation. In the photocatalytic reaction system, the generation of photogenerated electron-hole pairs, the separation and migration of electrons and holes, and the generation of active species (such as •OH and •O2) through surface redox reactions occur. - These active species can effectively oxidize and decompose organic pollutants. Ultimately, through a series of oxidative degradation reactions, organic pollutants are transformed into non-toxic and harmless products such as water and carbon dioxide. Organic pollutants (such as dyes, pesticides, drug residues, etc.) are reacted with hydroxyl radicals (•OH) and superoxide anions (•O2) on the surface of the photocatalyst. - The attack of these highly oxidizing reactive species gradually destroys the molecular structure. These species can oxidize C, C, and CH bonds in organic matter, causing macromolecules to degrade into smaller inorganic substances (such as carbon dioxide and water), or even become completely mineralized.

[0029] 4. The innovation of this invention lies in its high efficiency in pollutant removal, enhanced anti-pollution capabilities, multifunctional material design, and advantages in energy conservation and environmental protection. This combination not only improves the effectiveness of water treatment and air purification but also reduces system maintenance costs and energy consumption, promoting the intelligent and green development of environmental purification technology. Attached Figure Description

[0030] Figure 1 The XRD patterns are of the SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO photocatalyst particles synthesized in Example 1 of this invention.

[0031] Figure 2 SEM images of the SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO photocatalyst particles synthesized in Example 1 of this invention;

[0032] Figure 3 This is a flow chart of the photocatalysis-membrane separation application in Example 1;

[0033] Figure 4 This is a graph showing the effect of different membranes on the degradation rate of chlortetracycline pollutants in Example 2;

[0034] Figure 5 The graph shows the effect of different amounts of SrTiO3·Al-MgO on the degradation rate of chlortetracycline in Example 2.

[0035] Figure 6 This is a graph showing the degradation rate of chlortetracycline with different MgO loadings in Example 2.

[0036] Figure 7 This is a graph showing the rate of decrease in pollutant concentration due to SrTiO3·Al-MgO in Example 2.

[0037] Figure 8 This is a comparison chart of the cyclic application of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane in Example 2. Detailed Implementation Example 1

[0038] Preparation methods of photocatalyst particles and photocatalytic membranes for degrading organic pollutants in wastewater.

[0039] (1) MgO preparation process

[0040] Mg(OH)2 was used as a precursor and decomposed by high-temperature calcination to obtain MgO, which was then collected by grinding after cooling.

[0041] (2) Preparation process of SrTiO3 (solid-phase reaction method)

[0042] Strontium carbonate (SrCO3) and titanium dioxide (TiO2) in a certain proportion were mixed and then ground in a ball mill to ensure uniform distribution of the reactants. The mixed powder was heated to 700-900℃ to remove excess moisture and decompose the carbonates in the powder. Subsequently, the pre-calcined powder was further sintered at 1300-1500℃ to form SrTiO3 with a complete crystalline phase. After slow cooling, the powder was ground and collected.

[0043] (3) Preparation process of SrTiO3·Al (hydrothermal method)

[0044] SrCl2, TiCl4, and AlCl3 are dissolved in water or other solvents to form a mixed solution. After adjusting the pH of the solution, it is transferred to an autoclave and subjected to a hydrothermal reaction at 150-250℃ for 12-48 hours. During the reaction, perovskite-structured SrTiO3 gradually forms, and aluminum doping is incorporated into the crystal lattice. After cooling, the product is removed, washed, dried, and further heat-treated to improve crystallinity.

[0045] (4) Preparation process of SrTiO3·Al-MgO (non-in-situ method)

[0046] A certain amount of SrTiO3·Al powder was impregnated in an aqueous solution of Mg(OH)2, sonicated for 120 min, centrifuged, dried, and collected. The dried mixture was then placed in a tube furnace for firing under the following conditions: temperature 600℃, firing time 150 min, and flow rate 50 mL·min. -1 Argon gas was used to prepare SrTiO3·Al-MgO photocatalyst nanoparticles.

[0047] (5) Preparation of MgO / PSF-PVDF, SrTiO3 / PSF-PVDF, SrTiO3·Al / PSF-PVDF, and SrTiO3·Al-MgO / PSF-PVDF photocatalytic films

[0048] The substrate solution for the photocatalytic membrane was prepared by adding different amounts of MgO, SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO photocatalyst particles to a mixture of polysulfone (PSF), polyvinylidene fluoride (PVDF), lithium chloride (LiCl), N,N-dimethylacetamide (DMAC), and ethylene glycol dimethyl ether (EGME). After thorough mixing for 12 hours, the mixture was filtered and degassed using a vacuum pump. The degassed solution was then evenly spread onto a glass plate using a scraper to form a rectangular shape. The glass plate was then immersed in a deionized water bath for 24 hours to prepare MgO / PSF-PVDF, SrTiO3 / PSF-PVDF, SrTiO3·Al / PSF-PVDF, and SrTiO3·Al-MgO / PSF-PVDF photocatalytic membranes, respectively.

[0049] The photocatalyst particles synthesized in Example 1 were characterized by X-ray powder diffraction. The results showed that the synthesized photocatalyst particles were MgO, SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO, respectively. (See Appendix) Figure 1 .

[0050] The photocatalyst particles synthesized by the method in Example 1 were observed by scanning electron microscopy. The results showed that the synthesized nanoparticles were MgO, SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO, respectively. Figure 2(a, b, c, d) show SEM images of MgO, SrTiO3, SrTiO3·Al, and SrTiO3·Al-MgO photocatalyst particles. Figure (a) shows that the MgO sample exhibits a regular polyhedral shape, with a particle size of approximately 100 nm. The surface is relatively smooth, with clear edges and high crystallinity. Slight agglomeration exists between some particles. The SEM image reveals some cracks on the surface of the MgO particles, possibly due to stress release after high-temperature treatment. The particle size distribution is uneven, ranging from several hundred nanometers to several micrometers. Figure (b) shows that the SrTiO3 catalyst exhibits a blocky structure. Figure (c) shows that the SrTiO3·Al catalyst exhibits a cubic structure with a size of 1 μm. The cubic particles at the 1 μm size are doped with metallic aluminum. Figure (d) shows the SEM image of the composite material, revealing regular SrTiO3 particles with a size of approximately 1 micrometer and a cubic morphology. The particle surface is relatively smooth. Al and MgO particles are distributed on the surface of SrTiO3 particles, with some particles showing slight agglomeration, indicating good bonding of the composite material. See Appendix Figure 2 . Example 2

[0051] Based on photocatalysis-membrane separation cycle system

[0052] like Figure 3 As shown, a photocatalytic-membrane separation degradation cycle system is described. Organic wastewater is placed in a storage tank 1. Pressure gauge 4 and flow meter 5 are adjusted. A SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is cut into a circle with a radius of 3cm and placed in a photocatalytic membrane degradation device 8 for fixation. A 300W xenon lamp 7 is installed above the center of the photocatalytic membrane degradation device 8, ensuring that the center of the xenon lamp 7 coincides with the center of the photocatalytic membrane degradation device 8. The middle part of the photocatalytic membrane degradation device 8 is a circular transparent quartz glass, providing visible light for the operation of the device. Gear pump 3 is turned on, generating negative pressure, which draws the organic wastewater from the storage tank 1 into the circulation system. A portion of the organic wastewater flows back to the storage tank 1 through bypass pipe 2, while another portion enters the photocatalytic membrane degradation device 8 through pressure gauge 4. After exiting the photocatalytic membrane degradation device 8, the organic wastewater flows through pressure regulating valve 6 and flow meter 5, finally returning to the storage tank 1. The cycle lasts for 150 minutes. Example 3

[0053] A method for degrading organic pollutants in wastewater

[0054] The photocatalytic-membrane separation circulation system of Example 1 was used to degrade chlortetracycline in wastewater. The method is as follows: Organic wastewater containing chlortetracycline was placed in storage tank 1. Pressure gauge 4 and flow meter 5 were adjusted. A photocatalytic membrane was cut into a circle with a radius of 3 cm and placed in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 was installed above the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincided with the center of the photocatalytic membrane degradation device. The micro gear pump 3 was turned on to start the circulation treatment for 150 min. By adjusting the pressure control valve 6, the pressure value of the circulation system pressure gauge was set to 0.2 MPa, and the flow meter was adjusted to 40 mL / min. -1 .

[0055] Organic pollutants can be chlortetracycline, streptomycin, or gentamicin. The following explanation uses the degradation of chlortetracycline solution in wastewater as an example.

[0056] The concentration of chlortetracycline was determined using a UV-Vis spectrophotometer at wavelengths of K = 200–600 nm, and the results showed a maximum absorption peak near 369 nm. A linear relationship between concentration and absorbance was obtained by measuring a standard curve of concentration versus absorbance.

[0057] Degradation rate (%) = (C0 - C) t ) / C0×100%

[0058] Where C0 is the initial concentration of chlortetracycline (mg / L), C t It is the instantaneous concentration (mg / L) after a certain time (T) of degradation.

[0059] (I) The effect of different types of membranes on the degradation rate of chlortetracycline pollutants in wastewater

[0060] Method: Add 5 mg / L of chlortetracycline-simulated wastewater to storage tank 1. Adjust pressure gauge 4 and flow meter 5. Cut the photocatalytic membrane into a circle with a radius of 3 cm and place it in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 is installed above the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincides with the center of the photocatalytic membrane degradation device. Start the micro gear pump 3 to begin circulation treatment for 150 min. Adjust the pressure control valve 6 to maintain the pressure value of the circulation system pressure gauge at 0.2 MPa and adjust the flow meter to 40 mL / min. -1 .

[0061] The photocatalytic membranes used were MgO / PSF-PVDF, SrTiO3 / PSF-PVDF, SrTiO3·Al / PSF-PVDF, and SrTiO3·Al-MgO / PSF-PVDF. The degradation effects of different membrane types on chlortetracycline-simulated wastewater were as follows: Figure 4 As shown. By Figure 4It can be seen that the degradation efficiency of all types of membranes increases with the extension of the cycle time. The SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane has the highest efficiency in degrading chlortetracycline in wastewater, reaching 91.51% at 150 min. The SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is preferred in this invention.

[0062] (II) Effect of different dosages of SrTiO3·Al-MgO photocatalyst on the degradation rate of chlortetracycline in wastewater

[0063] Method: Add 5 mg / L of chlortetracycline-simulated wastewater to storage tank 1. Adjust pressure gauge 4 and flow meter 5. Cut the photocatalytic membrane into a circle with a radius of 3 cm and place it in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 is installed above the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincides with the center of the photocatalytic membrane degradation device. Start the micro gear pump 3 to begin circulation treatment for 150 min. Adjust the pressure control valve 6 to maintain the pressure value of the circulation system pressure gauge at 0.2 MPa and adjust the flow meter to 40 mL / min. -1 .

[0064] The SrTiO3·Al-MgO catalyst dosages were 0.1 g, 0.2 g, 0.3 g, and 0.4 g, respectively. The degradation effects of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane on chlortetracycline in wastewater with different SrTiO3·Al-MgO dosages were as follows: Figure 5 As shown. By Figure 5 It can be seen that the degradation efficiency of chlortetracycline increases with the extension of the cycle time, regardless of the amount of SrTiO3·Al-MgO used. The SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane with 0.3g of SrTiO3·Al-MgO has the highest efficiency in degrading chlortetracycline in wastewater, reaching 91.51% after 150 min. This invention preferably uses 0.3g of SrTiO3·Al-MgO photocatalyst particles to prepare the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane.

[0065] (III) Effect of different MgO loading rates on the degradation rate of chlortetracycline in wastewater

[0066] Method: Add 5 mg / L of chlortetracycline-simulated wastewater to storage tank 1. Adjust pressure gauge 4 and flow meter 5. Cut the photocatalytic membrane into a circle with a radius of 3 cm and place it in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 is installed above the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincides with the center of the photocatalytic membrane degradation device. Start the micro gear pump 3 to begin circulation treatment for 150 min. Adjust the pressure control valve 6 to maintain the pressure value of the circulation system pressure gauge at 0.2 MPa and adjust the flow meter to 40 mL / min. -1 .

[0067] The MgO loadings were 3%, 4%, 5%, and 6%, respectively. The effects of different MgO loadings on the degradation of chlortetracycline in wastewater were as follows: Figure 6 As shown. By Figure 6 It can be seen that when the MgO loading is 3%, 4%, 5%, and 6%, the degradation efficiency of chlortetracycline increases with the extension of the cycle time. When the MgO loading is 5%, the prepared SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane has the highest efficiency in degrading chlortetracycline in wastewater, reaching 91.51% after 150 min. The preferred MgO loading in this invention is 5%.

[0068] (iv) Effect of pollutant concentration on the efficiency of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane in degrading chlortetracycline in wastewater

[0069] Method: Aureomycin-simulated wastewater was added to storage tank 1. Pressure gauge 4 and flow meter 5 were adjusted. The photocatalytic membrane was cut into a circle with a radius of 3 cm and placed in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 was installed above the photocatalytic membrane degradation device, ensuring the center of the xenon lamp coincided with the center of the photocatalytic membrane degradation device. The micro gear pump 3 was turned on to begin circulation treatment for 150 min. By adjusting pressure control valve 6, the pressure value of the circulation system pressure gauge was set to 0.2 MPa, and the flow meter was adjusted to 40 mL / min. -1 .

[0070] The SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is effective in degrading different concentrations of chlortetracycline in wastewater, as shown in the following figures. Figure 7 As shown, the concentrations of the simulated chlortetracycline wastewater were 5 mg / L, 10 mg / L, and 15 mg / L, respectively. Figure 7 It can be seen that the degradation efficiency of chlortetracycline simulated wastewater of different concentrations increases with the extension of the circulation time. When the concentration of chlortetracycline simulated wastewater is 5 mg / L, its degradation efficiency is the highest, reaching 91.51% after 150 min. The preferred concentration of chlortetracycline simulated wastewater in this invention is 5 mg / L.

[0071] (V) Cyclic testing of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane

[0072] Method: Add 5 mg / L chlortetracycline-simulated wastewater to storage tank 1. Adjust pressure gauge 4 and flow meter 5. Cut the photocatalytic membrane into a circle with a radius of 3 cm and place it in the photocatalytic membrane degradation device for fixation. A 300 W xenon lamp 7 is installed above the photocatalytic membrane degradation device, ensuring that the center of the xenon lamp coincides with the center of the photocatalytic membrane degradation device. Start the micro gear pump 3 to begin circulation treatment for 150 min. Adjust the pressure control valve 6 to maintain the pressure value of the circulation system pressure gauge at 0.2 MPa and adjust the flow meter to 40 mL / min. -1 .

[0073] Figure 8 The figure shows the cycling test of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane. The conditions were: SrTiO3·Al-MgO dosage of 0.3 g, MgO loading of 5%, and chlortetracycline concentration in the simulated wastewater of 5 mg / L. Cycles were performed every 150 min for a total of four cycles. The figure shows that the degradation capacity still reached 83.38% after four cycles, indicating that the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane maintains high photocatalytic performance even after four cycles.

Claims

1. A method for preparing a SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane, characterized in that, The method comprises the following steps: S1: preparing SrTiO3·Al photocatalyst nanoparticles by using a hydrothermal method: SrCl2, TiCl4 and AlCl3 are dissolved in an aqueous solvent to form a mixed solution, the solution is adjusted to a pH value greater than 13, and then the solution is transferred to an autoclave for hydrothermal reaction at 150-250 DEG C for 12-48 hours; during the reaction process, a perovskite structure of SrTiO3 is gradually formed, and aluminum is doped into the crystal lattice; after cooling, the product is taken out, washed, dried and further heat treated to improve the crystallinity; S2: preparing SrTiO3·Al-MgO photocatalyst nanoparticles by using an ex situ method: SrTiO3·Al powder is immersed in Mg(OH)2 aqueous solution, after ultrasonic treatment for 120 min, centrifugation, drying and collection; the dried mixture is placed in a tube furnace for calcination, and the calcination conditions are as follows: temperature is 600 DEG C, calcination time is 150 min, argon flow rate is 50 mL·min -1 , and SrTiO3·Al-MgO photocatalyst nanoparticles are prepared. S3: preparing SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane: The base liquid of the photocatalytic membrane is: SrTiO3·Al-MgO photocatalyst particles are added into a mixed liquid of polysulfone PSF, polyvinylidene fluoride PVDF, lithium chloride LiCl, N, N-dimethylacetamide DMAC and ethylene glycol dimethyl ether EGME, and after being fully stirred and mixed for 12 hours, the mixed liquid is filtered through a filter screen and degassed by a vacuum pump; the degassed solution is uniformly pushed and spread on a glass plate by a film doctor knife to form a rectangle, and then the glass plate is immersed in a deionized water bath box for 24 hours to prepare the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane.

2. The application method of the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane prepared by the preparation method of claim 1, characterized in that, The method comprises a photocatalytic membrane separation and degradation organic pollutant circulating system, which comprises a liquid storage tank (1), a bypass pipe (2), a gear pump (3), a pressure gauge (4), a flow meter (5), an adjusting valve (6), a xenon lamp (7) and a photocatalytic membrane degradation device (8); The application process is as follows: The organic pollutant wastewater is placed in the liquid storage tank (1), the pressure gauge (4) and the flow meter (5) are adjusted, the SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane is cut into a circle with a radius of 3 cm, is placed in the photocatalytic membrane degradation device (8) and is fixed, a 300W xenon lamp (7) is installed above the center of the photocatalytic membrane degradation device (8) to ensure that the center of the xenon lamp (7) coincides with the center of the photocatalytic membrane degradation device (8), the middle part of the photocatalytic membrane degradation device (8) is a circular light-transmitting quartz glass to provide visible light for the working process of the photocatalytic membrane degradation device (8); the gear pump (3) is started to generate negative pressure, so that the organic wastewater in the liquid storage tank (1) is sucked into the circulating system, part of the organic wastewater flows back to the liquid storage tank (1) through the bypass pipe (2), and part of the organic wastewater enters the photocatalytic membrane degradation device (8) through the pressure gauge (4), and the organic wastewater flows through the pressure adjusting valve (6) and the flow meter (5) after flowing out of the photocatalytic membrane degradation device (8), and finally returns to the liquid storage tank (1) to be treated for 150 minutes.

3. The application method of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane according to claim 2, characterized in that, The photocatalytic membrane layer is arranged in the photocatalytic membrane degradation device (8).

4. The application method of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane according to claim 2, characterized in that, The pressure value of the pressure gauge (4) is 0.2 MPa.

5. The application method of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane according to claim 2, characterized in that, The flow meter (5) is 40 mL·min -1 .

6. The application method of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane according to claim 2, characterized in that, The initial concentration of the organic pollutant in the organic pollutant wastewater is 5-15 mg / L; the organic pollutant is an organic compound.

7. The application method of SrTiO3·Al-MgO / PSF-PVDF photocatalytic membrane according to claim 6, characterized in that, The organic compound is aureomycin, streptomycin, or kanamycin. The organic compound is aureomycin, streptomycin, or kanamycin.

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