Highly active photocatalyst capable of inhibiting generation of chlorinated products, and preparation method and application thereof

Abstract

The present application relates to high-activity photocatalyst capable of inhibiting the generation of chlorinated products and preparation method and application. By constructing a negative charged polymer modification layer on the surface of the photocatalyst, and reserving effective mass transfer channels for target pollutants in the modification layer, the photocatalyst can realize efficient degradation of pollutants, and by using electrostatic repulsion, the photocatalyst can prevent chloride ions from contacting the surface of the photocatalyst to participate in the photocatalytic process, thereby effectively controlling the generation of chlorinated products and significantly improving the safety of the pollutant degradation process. The composite photocatalytic material prepared by the present application shows good tolerance to different water environmental conditions, and has very strong practical application value in the safe and efficient removal of low-concentration and high-toxicity new pollutants in water.

Description

Technical Field

[0001] This invention relates to a highly active photocatalyst that can effectively inhibit the formation of chlorinated products, its preparation method and application, belonging to the field of composite environmentally friendly functional material preparation. Background Technology

[0002] In recent years, new pollutants with low concentrations and high toxicity have been continuously entering environmental water bodies, raising increasing concerns about their environmental risks. Taking antibiotics as an example, the widespread use of antibiotics has resulted in the prevalence of antibiotic residues in environmental water bodies worldwide. Although the detected concentrations are low, the volume and scope of pollution are large, and long-term exposure to low concentrations of antibiotics can induce resistance genes, thus seriously threatening ecological and environmental safety. Photocatalysis technology does not require continuous addition of reagents; it utilizes only sunlight and a photocatalyst to achieve rapid degradation of various new pollutants such as antibiotics, hormones, and pesticides. Furthermore, the reaction conditions are mild, and the treatment cost is low, demonstrating significant application potential in the remediation of low-concentration, highly toxic new pollutants. However, chloride ions are ubiquitous in actual water bodies, severely interfering with the photocatalytic degradation process of pollutants. For example, studies have found that chloride ions can rapidly consume photoactive species (such as hydroxyl radicals), which not only affects the degradation efficiency of antibiotics but, more seriously, leads to the formation of large amounts of chlorinated products. Chlorinated byproducts are not only more stable and difficult to degrade, but some can also induce resistance genes or various mutations in antibiotic-resistant strains through oxidative stress, thereby increasing the prevalence of antibiotic resistance. Controlling chlorinated byproducts is a common challenge in all advanced oxidation processes of chlorine-containing systems, and currently there is no effective strategy to address it. Although CN113248002A discloses a method for blocking the formation of chlorinated byproducts during the photocatalytic degradation of saline wastewater, by adding appropriate amounts of hole scavengers or hydroxyl radical scavengers to the photocatalytic system, it can effectively block chloride ion quenching of superoxide radicals, thus excluding chloride ions from the pollutant degradation pathway and effectively preventing the formation of chlorinated byproducts. However, this method requires the addition of additional scavengers and has a narrow scope of application, only applicable to photocatalytic degradation systems where superoxide radicals are the main active species. Therefore, it is essential to study a chlorinated byproduct blocking strategy with broad applicability and good efficacy.

[0003] Photocatalytic reactions primarily occur at the solid-liquid interface. Therefore, by altering the surface charge of the photocatalyst and utilizing electrostatic repulsion to restrict the migration of chloride ions from the aqueous phase to the photocatalyst surface, the probability of chloride ions contacting and reacting with photoactive species can be reduced. This suggests the potential to control chloride ion interference and thus inhibit the formation of chlorinated products. Publicly available information mentions applications that repel chloride ions through electrostatic interactions. For example, Chinese patent document CN107365098A describes a concrete rebar rust inhibitor that utilizes the negative charge of aromatic groups to repel chloride ions from migrating into the rebar matrix, thereby slowing down chloride ion corrosion. However, surface modification solely aimed at repelling chloride ions can cover the active sites on the photocatalyst surface, thus inhibiting the pollutant degradation ability of the photocatalytic material.

[0004] Therefore, constructing a photocatalytic material that can effectively inhibit the formation of chlorinated products and possesses high degradation activity is key to achieving efficient and safe degradation of new pollutants. However, there are currently no relevant research reports or technological products available in publicly available information. Summary of the Invention

[0005] In view of the aforementioned state of the prior art, the inventors of this invention, through in-depth and extensive research in the field of photocatalysis, discovered that by constructing a negatively charged polymer modification layer on the surface of a photocatalyst, and retaining effective mass transfer channels for the target pollutant within the modification layer, it is possible to achieve efficient pollutant degradation while simultaneously preventing chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process through electrostatic repulsion. This effectively controls the formation of chlorinated products and significantly improves the safety of the pollutant degradation process. This invention is based on the above findings.

[0006] Therefore, the first objective of this invention is to provide a highly active photocatalyst capable of suppressing the formation of chlorinated products. This photocatalyst can prevent chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process, thereby effectively controlling the formation of chlorinated products and significantly improving the safety of pollutant degradation processes.

[0007] A second objective of this invention is to provide a method for preparing the above-mentioned highly active photocatalyst capable of suppressing the formation of chlorinated products.

[0008] A third objective of this invention is to provide applications of the aforementioned highly active photocatalyst capable of inhibiting the formation of chlorinated products. The photocatalyst of this invention exhibits good tolerance to various aquatic environmental conditions and has significant practical application value in the safe and efficient removal of low-concentration, highly toxic new pollutants from water.

[0009] The fourth objective of this invention is to provide a method for suppressing the formation of chlorinated products during the photocatalytic degradation of pollutants. By constructing a negatively charged polymer modification layer on the surface of the photocatalyst, and retaining effective mass transfer channels for the target pollutant in the modification layer, the method achieves efficient degradation of pollutants while using electrostatic repulsion to prevent chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process, thereby effectively controlling the formation of chlorinated products.

[0010] The technical solution for achieving the above-mentioned objectives can be summarized as follows:

[0011] A highly active photocatalyst capable of inhibiting the formation of chlorinated products includes a photocatalyst matrix, wherein a negatively charged polymer modification layer is disposed on the surface of the photocatalyst matrix, and a mass transfer channel for the target pollutant is disposed in the modification layer.

[0012] According to the present invention, preferably, the photocatalyst matrix is ​​selected from at least one of titanium dioxide, zinc oxide, tantalum pentoxide, carbon nitride, bismuth vanadate, and tungsten trioxide.

[0013] According to the present invention, preferably, the negatively charged polymer modification layer is formed by polymer monomer polymerization reaction; more preferably, the polymer monomer is selected from at least one of methacrylic acid, acrylic acid, and itaconic acid;

[0014] Preferably, the polymerization reaction is carried out by free radical polymerization, sol-gel polymerization or microwave polymerization.

[0015] According to the present invention, preferably, the target pollutant is selected from at least one of antibiotics and pesticides; more preferably, the antibiotic includes at least one of sulfamethoxazole, ciprofloxacin, tetracycline, azithromycin, amoxicillin, and cephalexin;

[0016] The pesticides mentioned include at least one of carbendazim, metolachlor, imidacloprid, carbofuran, and tebuconazole;

[0017] According to the present invention, preferably, the mass transfer channel is constructed by a combination of the coating and elution process of the target pollutant in the polymer-modified layer.

[0018] According to the present invention, the preparation method of the above-mentioned highly active photocatalyst capable of suppressing the formation of chlorinated products includes the following steps:

[0019] Polymer monomers, target pollutant molecules, and photocatalysts are added to the reaction system to carry out a polymerization reaction. After the reaction is completed, the target pollutant molecules are eluted and removed, and the resulting solid product is dried to obtain the target product.

[0020] According to the present invention, preferably, the elution method is at least one of sodium hydroxide solution immersion, sodium carbonate solution immersion, ultraviolet irradiation, and Soxhlet extraction.

[0021] According to the present invention, the above-mentioned highly active photocatalyst capable of suppressing the formation of chlorinated products has the following applications:

[0022] Application of photocatalytic degradation of antibiotic-contaminated wastewater;

[0023] Application of photocatalytic degradation of pesticide-polluted wastewater.

[0024] According to the present invention, a method for inhibiting the formation of chlorinated products during the photocatalytic degradation of pollutants is also provided. This method involves constructing a negatively charged polymer modification layer on the surface of the photocatalyst, while retaining effective mass transfer channels for the target pollutant within the modification layer. Therefore, the present invention achieves efficient pollutant degradation while utilizing electrostatic repulsion to prevent chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process, thereby effectively controlling the formation of chlorinated products.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The photocatalytic material of the present invention can effectively inhibit chloride ions from participating in the photocatalytic process, significantly reduce the generation of toxic chlorinated products, and thus effectively improve the safety of the photocatalytic degradation process of pollutants.

[0027] 2. Because pollutant transport channels are reserved in the polymer modification layer, the active sites of the photocatalytic material of the present invention are not completely covered by the modification layer. Therefore, while inhibiting the formation of chlorinated products, it can achieve efficient degradation of pollutants.

[0028] 3. The photocatalytic material of the present invention exhibits good tolerance to different aquatic environmental conditions and has strong practical application value in the safe and efficient removal of low-concentration, highly toxic new pollutants in water. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of the negatively charged photocatalytic material (negative P25) prepared in Example 1 of the present invention;

[0030] Figure 2 Scanning electron microscope image of the original titanium dioxide photocatalyst (P25);

[0031] Figure 3 The infrared spectra of the negatively charged photocatalytic material (negative P25), the positively charged photocatalytic material (positive P25), and the original P25 prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0032] Figure 4 The diagram shows the zeta potential of the negatively charged photocatalytic material (negative P25), the positively charged photocatalytic material (positive P25), and the original P25 prepared in Example 1 and Comparative Example 1 of this invention.

[0033] Figure 5 This is a comparison of the performance of the negatively charged photocatalytic material (negative P25), the positively charged photocatalytic material (positive P25), and the original P25 prepared in Example 1 and Comparative Example 1 of the present invention in degrading sulfamethazine in a chlorine-free system.

[0034] Figure 6 This is a comparison of the performance of the negatively charged photocatalytic material (negative P25), the positively charged photocatalytic material (positive P25), and the original P25 prepared in Example 1 and Comparative Example 1 of the present invention in degrading sulfamethazine in a chlorine-containing system.

[0035] Figure 7 This is a comparison of the amount of chlorinated products produced by the negatively charged photocatalytic material (negative P25), the positively charged photocatalytic material (positive P25), and the original P25 after degradation of sulfamethazine in a chlorine-containing system, prepared in Example 1 and Comparative Example 1 of the present invention.

[0036] Figure 8 Mutagenicity analysis of sulfamethazine and its chlorinated products generated during degradation;

[0037] Figure 9 This is a comparison of the amount of chlorinated products produced by the negatively charged photocatalytic material (negative P25) prepared in Example 1 of the present invention and the original P25 in water containing calcium and magnesium ions.

[0038] Figure 10 This is a comparison of the amount of chlorinated products produced by the negatively charged photocatalytic material (negative P25) prepared in Example 1 of the present invention and the original P25 in different types of water bodies. Detailed Implementation

[0039] This invention constructs a negatively charged polymer modification layer on the surface of a photocatalyst, while retaining effective mass transfer channels for the target pollutant within the modification layer. This achieves efficient pollutant degradation while simultaneously utilizing electrostatic repulsion to prevent chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process, thereby effectively controlling the formation of chlorinated products and significantly improving the safety of the pollutant degradation process. Furthermore, the composite photocatalytic material prepared by this invention exhibits good tolerance to various aquatic environmental conditions, demonstrating significant practical application value in the safe and efficient removal of low-concentration, highly toxic new pollutants from water.

[0040] The present invention provides a highly active photocatalyst capable of suppressing the formation of chlorinated products, comprising a photocatalyst matrix, wherein a negatively charged polymer modification layer is disposed on the surface of the photocatalyst matrix, and a mass transfer channel for the target pollutant is disposed in the modification layer.

[0041] In one or more preferred embodiments, the photocatalyst matrix is ​​selected from at least one of titanium dioxide, zinc oxide, tantalum pentoxide, carbon nitride, bismuth vanadate, and tungsten trioxide;

[0042] Preferably, the photocatalyst can be a nano- or micro-sized powder, or a photocatalyst coating supported on a carrier.

[0043] In one or more preferred embodiments, the negatively charged polymer modification layer is formed by polymer monomer polymerization; preferably, the polymer monomer is selected from at least one of methacrylic acid, acrylic acid, and itaconic acid.

[0044] According to the present invention, the negatively charged polymer modification layer cannot be too thick, otherwise it will block contaminants from contacting the active sites of the photocatalyst; nor can it be too thin, because it will lose its function of repelling chloride ions. Therefore, in one or more preferred embodiments, the molar ratio of photocatalyst to polymer monomer is controlled between 1:1 and 1:10.

[0045] In one or more preferred embodiments, the target pollutant is selected from at least one of antibiotics and pesticides; preferably, the antibiotics include sulfamethoxazole, ciprofloxacin, tetracycline, azithromycin, amoxicillin, and cephalexin.

[0046] The pesticides mentioned include carbendazim, metolachlor, imidacloprid, carbofuran, and tebuconazole.

[0047] In one or more preferred embodiments, the mass transfer channel is constructed by a combination of the coating and elution process of the target pollutant in the polymer-modified layer.

[0048] According to the present invention, the preparation method of the above-mentioned highly active photocatalyst capable of suppressing the formation of chlorinated products includes the following steps:

[0049] Polymer monomers, target pollutant molecules, and photocatalysts are added to the reaction system to carry out a polymerization reaction. After the reaction is completed, the target pollutant molecules are eluted and removed, and the resulting solid product is dried to obtain the target product.

[0050] A negatively charged polymer modification layer is constructed on the surface of a photocatalyst through a polymerization reaction; after the polymerization reaction is completed, pollutant molecules are eluted and removed. This process aims to provide an effective mass transfer channel for the target pollutant in the modification layer.

[0051] In one or more preferred embodiments, the polymerization reaction is carried out by free radical polymerization, sol-gel polymerization, or microwave polymerization;

[0052] Preferably, when free radical polymerization is used, polymerization is carried out under the action of a crosslinking agent and an initiator;

[0053] Further preferred crosslinking agents are selected from trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, and glycidyl methacrylate, and initiators are selected from azobisisobutyronitrile, phenyl dimethyl acetal, potassium persulfate, and peroxybenzoyl.

[0054] The molar ratio of polymer monomer to crosslinking agent is 1:1-1:5, and the mass concentration of initiator is 0.1%-2.0%.

[0055] Preferably, the molar ratio of the target pollutant to the polymer monomer is 1:2 to 1:8;

[0056] Preferably, the polymerization reaction temperature is 50-90℃.

[0057] In one or more preferred embodiments, the elution method is at least one of sodium hydroxide solution immersion, sodium carbonate solution immersion, ultraviolet irradiation, and Soxhlet extraction;

[0058] Preferably, when using Soxhlet extraction elution, after extraction with a mixture of methanol and acetic acid, the sample is washed multiple times with ethanol and distilled water. The volume ratio of methanol to acetic acid is preferably controlled at 9:1.

[0059] According to the present invention, a preferred embodiment of a method for preparing a highly active photocatalyst capable of suppressing the formation of chlorinated products includes the following steps:

[0060] (1) Disperse the original photocatalyst in acetonitrile, add the target pollutant and polymer monomer after sonication, stir completely, and then add the crosslinking agent and initiator in sequence; control the molar ratio of photocatalyst, target pollutant, polymer monomer and crosslinking agent to be 1:1:4:8;

[0061] (2) Nitrogen gas was introduced into the mixture obtained in step (1) under constant stirring. After sealing, the mixture was subjected to polymerization at a temperature of 50-90℃. After the reaction was completed, the mixture was cooled to room temperature and the solid sample obtained by centrifugation was washed multiple times with ethanol and distilled water.

[0062] (3) The solid sample obtained in step (2) is placed in a Soxhlet extractor and extracted with a 9:1 volume ratio of methanol and acetic acid. Then it is washed multiple times with ethanol and distilled water. After drying, a highly active photocatalyst that can inhibit the formation of chlorinated products is obtained.

[0063] According to the present invention, the application of the above-mentioned highly active photocatalyst capable of suppressing the formation of chlorinated products is as follows:

[0064] Application of photocatalytic degradation of antibiotic-contaminated wastewater;

[0065] Application of photocatalytic degradation of pesticide-polluted wastewater.

[0066] According to the present invention, a method for inhibiting the formation of chlorinated products during the photocatalytic degradation of pollutants is also provided. This method involves constructing a negatively charged polymer modification layer on the surface of the photocatalyst, while retaining effective mass transfer channels for the target pollutant within the modification layer. Therefore, the present invention achieves efficient pollutant degradation while utilizing electrostatic repulsion to prevent chloride ions from contacting the photocatalyst surface and participating in the photocatalytic process, thereby effectively controlling the formation of chlorinated products.

[0067] The present invention will be further explained below through specific embodiments, comparative examples, and in conjunction with the accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0068] Example 1

[0069] A method for preparing a highly active photocatalyst that can suppress the formation of chlorinated products includes the following steps:

[0070] (1) The original titanium dioxide photocatalyst (P25) was dispersed in acetonitrile and sonicated for 30 minutes. Then, the target pollutant sulfamethazine and methacrylic acid monomer were added and stirred for 20 minutes. Finally, trimethylolpropane trimethacrylate crosslinking agent and azobisisobutyronitrile initiator were added sequentially. During the experiment, the molar ratio of photocatalyst, target pollutant, monomer and crosslinking agent was controlled to be 1:1:4:8.

[0071] (2) The mixture obtained in step (1) was purged with nitrogen for 30 minutes with constant stirring, sealed, and then polymerized in a water bath at 70°C for 24 hours. After cooling to room temperature, the solid obtained by centrifugation was washed multiple times with ethanol and distilled water.

[0072] (3) The solid sample obtained in step (2) is placed in a Soxhlet extractor and a mixture of methanol and acetic acid in a volume ratio of 9:1 is used as the extraction solution. The Soxhlet extract is performed at 110°C for 24 hours. The extracted sample is washed multiple times with ethanol and distilled water and dried in an oven at 80°C to obtain a highly active photocatalyst that can inhibit the formation of chlorinated products (named "Negative P25").

[0073] The negative P25 prepared in Example 1 was scanned by electron microscopy, as shown below. Figure 1 As shown, its surface morphology is similar to that of the original P25 ( Figure 2 There was no significant difference, indicating that the preparation process did not lead to significant catalyst agglomeration.

[0074] Infrared spectral analysis was performed on the original P25 and negative P25, and the results are as follows: Figure 3As shown. It can be seen that in the infrared spectrum of the original P25, 500-700 cm⁻¹ -1 The absorption peak at 3400 cm⁻¹ is a characteristic peak of Ti-O. -1 and 1600cm -1 The absorption peak at this point is related to -OH. Negative P25 is a polymer formed by adding a crosslinking agent and monomers to P25. Compared to the original P25, negative P25 shows an absorption peak in the 1000-1475 cm⁻¹ range. -1 There are multiple absorption peaks within the polymer, mainly due to the bending vibrations within the CH plane, the stretching vibrations of CO, and the monoskeletal vibrations of CC. Meanwhile, negative P25 shows an absorption peak at 1726 cm⁻¹. -1 The presence of distinct characteristic peaks indicates that the C=O stretching vibration within the -COOH group is caused by these new peaks. The appearance of these new peaks proves that a negatively charged modified layer rich in -COOH has been successfully constructed on the negative P25 surface.

[0075] Zeta potential analysis was performed on the original P25 and negative P25, and the results are shown in [Figure number missing]. Figure 4 It can be seen that under all tested pH conditions, the zeta potential of negative P25 is about 10 mV lower than that of P25, and the isoelectric point of negative P25 also drops significantly from pH=5.4 of P25 to pH=3.2. Therefore, negatively charged P25 will exhibit the ability to repel chloride ions based on electrostatic repulsion over a wide pH range (pH>3.2).

[0076] Example 2

[0077] As described in Implementation List 1, the difference is:

[0078] In step (1), the monomer is replaced with acrylic acid.

[0079] Example 3

[0080] As described in Implementation List 1, the difference is:

[0081] In step (1), the monomer is replaced with itaconic acid.

[0082] Comparative Example 1

[0083] As described in Example 1, the difference is:

[0084] In step (1), the monomer methacrylic acid was replaced with o-phenylenediamine, and the resulting sample was named "positive P25".

[0085] Infrared spectroscopy analysis was performed on the product positive P25 obtained in this comparative example, and the results are as follows: Figure 3 As shown. Unlike P25 and negative P25, positive P25 is between 1500-1650 cm. -1The absorption peak within the sample is due to the NH bending vibration, which originates from the -NH2 group in the monomer o-phenylenediamine. Zeta potential analysis was performed on positive P25. Figure 4 As can be seen, the zeta of positive P25 is significantly higher than that of both P25 and negatively charged P25.

[0086] Experimental Example 1

[0087] The photocatalytic degradation performance of sulfamethazine was compared between the negative P25 prepared in Example 1, the positive P25 prepared in Comparative Example 1, and the original P25 through photocatalytic degradation experiments. The experimental methods are as follows:

[0088] All photocatalytic experiments were conducted with continuous stirring in a 400 mL quartz reactor using a 10 W UV lamp. 0.15 g of photocatalyst was dispersed in 300 mL of sulfamethazine solution (50 mg / L) and allowed to adsorb for 30 minutes in the dark to reach adsorption equilibrium. Afterward, the light source was turned on, and appropriate amounts of solution were taken at certain reaction times (0, 5, 10, 20, 30, 40, and 60 minutes). The solutions were filtered through a 0.22 μm filter membrane, and the concentration of residual antibiotics in the filtrate was determined using liquid chromatography. For the chlorine-containing system, sodium chloride was added to the sulfamethazine solution before adding the photocatalyst, while keeping other experimental conditions constant, to control the chloride ion concentration at 0.5 mol / L.

[0089] Experimental results are as follows Figure 5 and Figure 6 As shown, in the chlorine-free system, both negative P25 and positive P25 degrade antibiotics faster than the P25 system. This indicates that even with reserved pollutant transport channels, the active sites of the photocatalyst are not completely covered by the polymer modification layer, yet efficient pollutant degradation can still be achieved. Furthermore, when chloride ions are present in the system, the degradation rate of sulfamethazine in the positive P25 system is significantly inhibited, while negative P25 still exhibits a faster photocatalytic degradation rate than the P25 system. This demonstrates that the negative charge on the negative P25 surface effectively suppresses the interference of chloride ions on the photocatalytic process.

[0090] Experimental Example 2

[0091] Gas chromatography was used to compare the amounts of chlorinated products produced during the degradation of sulfamethazine in a chlorine-containing system by negative P25, positive P25, and virgin P25. The experimental protocol is as follows:

[0092] Samples were taken 20 minutes after the photocatalytic reaction. The samples were extracted with methyl tert-butyl ether and the concentration of chloroacetic acid was analyzed by gas chromatography.

[0093] Experimental results are as follows Figure 7As shown, although chloroacetic acid (monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid) was detected in all three systems (negative P25, positive P25, and P25) when chloride ions were present, the concentration was lowest in the negative P25 system. The concentration of chloroacetic acid in the P25 system was 6.3 times that in the negative P25 system, and the concentration in the positive P25 system was 9.0 times that in the negative P25 system. This indicates that the negative P25 system effectively inhibits the formation of chlorinated products.

[0094] Experimental Example 3

[0095] The mutagenicity of sulfamethazine and its chlorinated degradation products was assessed using the toxicity assessment software (TEST) developed by the U.S. Environmental Protection Agency. The results are as follows: Figure 8 As shown in the figure, the mutagenicity of all three chloroacetic acids is higher than that of sulfamethoxazole, meaning they pose a greater risk of altering the total number and structure of chromosomes. Furthermore, TEST assessment revealed that trichloroacetic acid had a higher bioaccumulation factor than sulfamethoxazole, and a higher bioaccumulation factor indicates a greater likelihood of product accumulation in the organism. In addition, all three chloroacetic acids exhibited higher developmental toxicity than sulfamethoxazole, suggesting that these products are more likely to interfere with embryonic development.

[0096] From the concentration of chloroacetic acid detected in Experiment Example 2 ( Figure 7 The amount of chlorinated products generated in the negative P25 system is much lower than that in the original P25 and positive P25 systems. Therefore, negative P25 can effectively improve the safety of antibiotic degradation process in chlorine-containing systems.

[0097] Test Example 4

[0098] The negative P25 surface carries a negative charge; therefore, cations such as calcium and magnesium ions in the water may affect the chloride ion repulsion performance of the negative P25. The amount of chloride products produced by the P25 and negative P25 photocatalytic systems in the presence of 0.05 mol / L calcium / magnesium ions was compared. The experimental results are as follows: Figure 9 As shown, negative P25 can still effectively inhibit the formation of chloride products in the presence of calcium and magnesium ions, indicating that its ability to repel chloride ions is not lost due to the presence of common cations in water.

[0099] Experimental Example 5

[0100] The amounts of chlorinated products generated during the degradation of sulfamethazine by P25 and negative P25 in various water bodies were compared, including high-salinity wastewater (0.5 mol / L sodium chloride solution), secondary sedimentation tank effluent, tap water, and seawater. Results are as follows: Figure 10 As shown in the figure, it can be seen that negative P25 can effectively inhibit the formation of chlorinated products in the above four types of water bodies, indicating that it has a very strong adaptability to water quality.

Claims

1. A method for inhibiting the formation of chlorinated products during the degradation of pollutants by a photocatalyst, characterized in that, The method is by constructing a negative electric polymer modification layer on the surface of the photocatalyst matrix, and reserving effective mass transfer channels for the target pollutants in the modification layer, and the mass transfer channels are constructed by the combination of the coating and elution process of the target pollutants in the polymer modification layer; The negative electric polymer modification layer is polymerized from polymer monomers selected from at least one of methacrylic acid, acrylic acid and itaconic acid, and the polymerization mode is free radical polymerization, sol-gel polymerization or microwave polymerization; The photocatalyst is prepared by the following steps: putting the polymer monomers, target pollutant molecules and photocatalyst matrix into a reaction system for polymerization reaction, removing the target pollutant molecules after the reaction is completed, and drying the obtained solid product to obtain the target product.

2. The method of claim 1, wherein the photocatalyst is Ti02. The photocatalyst matrix is selected from at least one of titanium dioxide, zinc oxide, tantalum pentoxide, carbon nitride, bismuth vanadate and tungsten trioxide.

3. The method of claim 1, wherein the photocatalyst is Ti02. The target pollutants are selected from at least one of antibiotics and pesticides.

4. The method of claim 3, wherein the photocatalyst is Ti02. The antibiotics include at least one of sulfamethoxazole, ciprofloxacin, tetracycline, azithromycin, amoxicillin and cephalexin, and the pesticides include at least one of carbendazim, isopropylammonium, imidacloprid, carbofuran and tebuconazole.

5. The method of inhibiting the formation of chlorinated products during the degradation of pollutants by a photocatalyst according to claim 1, wherein, The elution mode is at least one of sodium hydroxide solution immersion, sodium carbonate solution immersion, ultraviolet irradiation and Soxhlet extraction.

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