Composite material for photocatalytic degradation of pfoa and preparation method thereof

Abstract

The application relates to the field of photocatalysis, in particular to a composite material for photocatalytic degradation of PFOA and a preparation method thereof. The composite material comprises the following steps: step one: using titanium foil as an anode and a nickel sheet as a cathode, carrying out anodic oxidation, and then annealing to obtain TiO2-NT; step two: first, acid pickling TiO2-NT, and then preparing TiO2-NT suspension liquid; adding chloroplatinic acid, a dispersing agent and potassium borohydride into the TiO2-NT suspension liquid to prepare a Pt / TiO2-NT composite material; step three: coating ammonium perrhenate on the Pt / TiO2-NT composite material, and then sintering, repeating 1-2 times to obtain a modified Pt / TiO2-NT composite material; and step four: preparing a MIP-Pt / TiO2-NT composite material through a molecular imprinting technology.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, specifically to a composite material for photocatalytic degradation of PFOA and its preparation method. Background Technology

[0002] Since the 1950s, perfluorooctanoic acid (PFOA), as a man-made organic compound, has been used globally in various products. Due to its unique properties of being hydrophobic and oleophobic while also possessing high surface activity and thermal stability, PFOA is commonly used as a stain-resistant agent in carpets, upholstery, and textiles, and as a high-performance fire extinguishing material. Due to its widespread use, PFOA has become one of the most frequently detected persistent organic pollutants (POPs) in water, sediments, wildlife, and even human tissue, and is now listed in the Stockholm Convention on Persistent Organic Pollutants. Furthermore, PFOA can accumulate in the human body over a long period after ingestion, adversely affecting the immune, reproductive, and endocrine systems. Increasing health research data indicates that exposure to PFOA can lead to numerous health problems, such as thyroid hormone disorders, impaired immune systems, and low birth weight in infants. On December 29, 2022, the Ministry of Ecology and Environment released a list of key new pollutants under control, including PFOA, which officially came into effect on March 1, 2023. Therefore, there is an urgent need to develop an effective technology for the removal of PFOA.

[0003] Studies have shown that photocatalysis is a promising technology for addressing persistent organic pollutant (PFOA) pollution and energy constraints, as it can meet the requirements for PFOA removal without consuming additional energy. Under sunlight irradiation, photocatalysts are excited to generate redox-active substances (such as superoxide radicals, hydroxyl radicals, and holes), which contribute to PFOA degradation. However, the recombination of excited electrons and holes during migration limits the efficiency of photocatalytic PFOA degradation. In practical applications, the low concentration and complex composition of PFOA in water bodies mean that the adsorption and catalytic degradation of PFOA by photocatalysts are affected by other pollutants. Therefore, suppressing photogenerated electron-hole recombination and improving the adsorption capacity of photocatalysts for PFOA are crucial for the efficient degradation of PFOA using photocatalytic technology. Molecular imprinting (MIT) technology offers the opportunity to endow photocatalysts with good selectivity because they can be coupled with customized acceptors that can selectively recognize and bind target molecules with high affinity. The Fermi level (EF) of noble metals is lower than that of semiconductors. When noble metals come into contact with semiconductors, a Schottky barrier is formed between them to balance the EF of the semiconductor and the noble metal. This barrier acts as an effective electron trap, suppressing the recombination of photogenerated electrons and holes. Therefore, using noble metal nanoparticles and molecularly imprinted polymers (MIPs) to co-modify photocatalysts will enhance the photocatalytic performance of the modified photocatalysts, thereby improving the removal efficiency of PFOA. Summary of the Invention

[0004] The purpose of this invention is to provide a titanium dioxide nanotube (TiO2-NT) photocatalytic material co-modified with noble metal platinum and molecularly imprinted polymer (MIP) to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: Platinum (Pt) nanoparticles are loaded onto TiO2-NT, which is simple to prepare and has stable performance, by chemical reduction method to obtain Pt / TiO2-NT composite material; then, the Pt / TiO2-NT composite material is modified by MIP to finally obtain MIP-Pt / TiO2-NT composite material.

[0006] A composite material for photocatalytic degradation of PFOA and its preparation method, comprising the following steps:

[0007] Step 1: Using the cleaned titanium foil as the anode and the nickel sheet as the cathode, both are simultaneously immersed in the electrolyte. Under stirring, voltage is applied to perform anodizing treatment, and finally annealing is performed to obtain TiO2-NT.

[0008] Step 2: First, pretreat TiO2-NT and then prepare it into a TiO2-NT suspension; add chloroplatinic acid and dispersant, stir and mix, then add potassium borohydride to react, and finally filter, wash and dry to obtain Pt / TiO2-NT composite material;

[0009] Step 3: Apply ammonium perrhenate to the Pt / TiO2-NT composite material, and then sinter it. Repeat this process 1 to 2 times to obtain the modified Pt / TiO2-NT composite material.

[0010] Step 4: Prepare MIP-Pt / TiO2-NT composite material by molecular imprinting technology using the modified Pt / TiO2-NT composite material.

[0011] Further, the specific process of step one is as follows: (1) First, use acetone and deionized water to ultrasonically clean the titanium foil for 20 to 40 minutes; (2) In a cylindrical electrochemical reactor with a DC power supply, use the cleaned titanium foil as the anode and the nickel sheet as the cathode, and insert the anode and cathode into the electrolyte; perform magnetic stirring at room temperature and apply a constant voltage of 20 to 50V. After anodic oxidation for 5 to 8 hours, rinse the anode with deionized water 1 to 3 times, and after annealing, obtain highly ordered and vertically arranged TiO2-NT.

[0012] Furthermore, the electrolyte is prepared by mixing ethylene glycol and ammonium fluoride; wherein the concentration of ethylene glycol is 0.085 mol / L and the concentration of ammonium fluoride is 0.5 mol / L.

[0013] Furthermore, the annealing process includes: annealing temperature of 500–650°C and annealing time of 0.5–2 hours.

[0014] Further, the specific process of step two is as follows: (1) At 100-110℃, TiO2-NT is immersed in 10wt% oxalic acid solution, and after acid washing for 1-3 hours, it is taken out and washed with deionized water 1-3 times to obtain pretreated TiO2-NT; (2) Pretreated TiO2-NT is added to deionized water and ultrasonically dispersed for 20-40 minutes to prepare a TiO2-NT suspension of 14g / L; (3) Chloroplatinic acid solution and dispersant are added to TiO2-NT suspension and mixed and stirred for 10-30 minutes to obtain a reaction solution; (4) Potassium borohydride solution is added dropwise to the reaction solution. After the addition is completed, the reaction continues for 10-15 minutes to end the reaction. After filtration, washing and drying, Pt / TiO2-NT composite material is obtained.

[0015] Furthermore, the concentration of the chloroplatinic acid solution is 8–15 mM; the concentration of the potassium borohydride solution is 0.5–1.5 g / L; and the Pt / Ti content ratio is 1.0–1.5 at%.

[0016] Furthermore, the specific process of step three is as follows: a 10-15 wt% ammonium perrhenate solution is brushed onto both sides of the Pt / TiO2-NT composite material, and sintered at 420-500℃ for 5-10 minutes. The brushing-sintering process is repeated 1-2 times to obtain the modified Pt / TiO2-NT composite material.

[0017] Further, the specific process of step four is as follows: (1) The modified Pt / TiO2-NT composite material is soaked in 0.8 mol / L sodium hydroxide solution for 20-40 minutes, then taken out, washed, and dried to obtain pretreated Pt / TiO2-NT composite material A; (2) The pretreated Pt / TiO2-NT composite material A is immersed in anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane for 10-30 minutes, then the pretreated Pt / TiO2-NT composite material A is purged with nitrogen for 10-30 minutes, then placed in an insulated box and kept at 50-60℃ for 3-6 hours. After it cools naturally to room temperature, it is finally washed with toluene and acetonitrile respectively, and dried under nitrogen to obtain pretreated Pt / TiO2-NT composite material A. Pt / TiO2-NT composite material B; (3) Add the template (PFOA) to a mixed solution containing methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate and azobisisobutyronitrile, disperse it by ultrasonication for 5 to 15 minutes, and then slowly and evenly drop it onto both sides of the pretreated Pt / TiO2-NT composite material B. Insert it into a columnar quartz tube and purge it with nitrogen for 10 to 40 minutes in a sealed environment to obtain the pretreated Pt / TiO2-NT composite material C; (4) Perform a polymerization reaction on the pretreated Pt / TiO2-NT composite material C under 350nm ultraviolet light for 10 to 15 hours. After the reaction is completed, wash the product with methanol solution until the molecular template is not detected in the eluent. Finally, the MIP-Pt / TiO2-NT composite material is prepared.

[0018] Furthermore, in the anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane, the volume ratio of 3-aminopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and anhydrous toluene is 1:1:48.

[0019] Furthermore, in the mixed solution prepared from the template, methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile, the concentration of the template is 0.02 mol / L, the concentration of acrylamide is 0.5 mol / L, the concentration of ethylene glycol dimethacrylate is 1.5 mol / L, the concentration of azobisisobutyronitrile is 0.05 mol / L, and the methanol / acetonitrile solution is prepared by mixing methanol and acetonitrile in a volume ratio of 1:1.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] (1) The MIP-Pt / TiO2-NT composite material of the photocatalyst produced by the present invention with PFOA as MIP template has better selectivity and adsorption of PFOA pollutants compared with traditional TiO2-NT, and has a low charge recombination rate, which makes the photocatalytic degradation of PFOA more efficient.

[0022] (2) In this invention, titanium foil is used as a template to prepare TiO2-NT by anodic oxidation. The preparation is simple and controllable. In addition to photocatalysis, TiO2-NT can also be applied to adsorption. Moreover, due to its high specific surface area and active sites, TiO2-NT has strong selectivity and adsorption after modification and can adsorb target molecules.

[0023] (3) Because the noble metal Pt can provide high reactivity, as well as good selectivity and stability; Pt can also resist the interference of harmful substances, so it is widely used in redox reactions, cracking reactions and other fields; in addition, Pt has good controllability and ease of use, so it plays an important role in the research of catalyst preparation technology. In this scheme, Pt is deposited onto TiO2-NT by chemical deposition, and a dispersant is added to make Pt deposit more uniform, thereby obtaining a Pt / TiO2-NT composite material with higher catalytic activity.

[0024] (4) In the scheme, since the Pt catalyst layer will dissolve and fall off over time, the catalytic activity will decrease. In order to ensure the catalytic activity of the Pt / TiO2-NT composite material, a layer of ammonium perrhenate is also coated on the Pt / TiO2-NT composite material and sintered to decompose rhenium heptoxide. Rhenium heptoxide has excellent catalytic activity, which can ensure the activity of Pt. At the same time, after sintering, the bonding force between Pt and TiO2-NT will be better and it will not fall off easily. The two together enhance the catalytic ability of MIP-Pt / TiO2-NT.

[0025] (5) MIP can give photocatalysts good selectivity, enabling them to selectively recognize and bind target molecules with high affinity. In addition, by modifying TiO2-NT with Pt and MIP, not only can the photogenerated electron-hole recombination of TiO2 be effectively inhibited, but the charge lifetime can also be extended, and the adsorption capacity of the target pollutant PFOA can be enhanced, thereby improving the degradation efficiency of PFOA. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that there are no special restrictions on the suppliers of the raw materials involved in this invention. Exemplary examples include: in the following embodiments:

[0028] The titanium foil has a purity of 99.7% and a thickness of 0.07 mm, and was supplied by China Haiji Titanium & Nickel Co., Ltd.

[0029] Ethylene glycol was supplied by Shanghai Maclean Biochemical Technology Co., Ltd.

[0030] Ammonium fluoride was supplied by Shanghai Maclean Biochemical Technology Co., Ltd.

[0031] Chloroplatinic acid was provided by Shanghai Maclean Biochemical Technology Co., Ltd.

[0032] Potassium borohydride was supplied by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0033] 3-Aminopropyltriethoxysilane was provided by Shanghai Maclean Biochemical Technology Co., Ltd.

[0034] 3-Methacryloxypropyltrimethoxysilane was provided by Shanghai Maclean Biochemical Technology Co., Ltd.

[0035] PFOA was provided by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] PFOS was provided by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0037] Ammonium perrhenate was provided by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0038] A solution containing 3-aminopropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane and anhydrous toluene was prepared by mixing 3-aminopropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane in a volume ratio of 1:1:48.

[0039] PFOA, methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were mixed and ultrasonically dispersed for 10 minutes to prepare template mixture solution A; wherein the concentration of PFOA was 0.02 mol / L, the concentration of acrylamide was 0.5 mol / L, the concentration of ethylene glycol dimethacrylate was 1.5 mol / L, the concentration of azobisisobutyronitrile was 0.05 mol / L, and the methanol / acetonitrile solution was prepared by mixing methanol and acetonitrile in a volume ratio of 1:1.

[0040] PFOS, methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile were mixed and ultrasonically dispersed for 10 minutes to prepare template mixture solution B; wherein the concentration of PFOS was 0.02 mol / L, the concentration of acrylamide was 0.5 mol / L, the concentration of ethylene glycol dimethacrylate was 1.5 mol / L, the concentration of azobisisobutyronitrile was 0.05 mol / L, and the methanol / acetonitrile solution was prepared by mixing methanol and acetonitrile in a volume ratio of 1:1.

[0041] Example 1: A method for preparing a composite material for photocatalytic degradation of PFOA:

[0042] Step 1: (1) The titanium foil was ultrasonically cleaned with acetone and deionized water for 30 minutes in sequence; (2) In a cylindrical electrochemical reactor with DC power supply, the cleaned titanium foil was used as the anode and the nickel sheet was used as the cathode. The anode and cathode were inserted into an electrolyte prepared by mixing 0.085 mol / L ethylene glycol and 0.5 mol / L ammonium fluoride. The mixture was magnetically stirred at 20°C and a constant voltage of 20V was applied for anodic oxidation. After 6 hours of reaction, the anode was rinsed with deionized water 3 times. After drying, it was placed in a muffle furnace and annealed at 600°C for 1 hour under nitrogen protection to obtain highly ordered and vertically arranged TiO2-NT.

[0043] Step 2: (1) Immerse 40g of TiO2-NT in 10wt% oxalic acid solution at 100℃, acid wash for 1 hour, take it out and wash it 3 times with deionized water to obtain pretreated TiO2-NT; (2) Add the pretreated TiO2-NT to deionized water, and disperse it by ultrasonication for 30 minutes to prepare a TiO2-NT suspension of 14g / L; (3) Add 2mL of 12mM chloroplatinic acid solution and 10mL of polyethylene glycol to the TiO2-NT suspension, mix and stir for 30 minutes to obtain a reaction solution; (4) Add 2mL of 1g / L potassium borohydride solution to the reaction solution, and after the addition is complete, continue the reaction for 15 minutes to end the reaction. After filtration and washing, dry at 110℃ to obtain Pt / TiO2-NT composite material;

[0044] Step 3: Apply a 15wt% ammonium perrhenate solution to both sides of the Pt / TiO2-NT composite material, sinter at 440℃ for 5 minutes, and repeat the coating-sintering process twice to obtain the modified Pt / TiO2-NT composite material.

[0045] Step 4: (1) Soak the modified Pt / TiO2-NT composite material in 0.8 mol / L sodium hydroxide solution for 40 minutes, then take it out, rinse it with deionized water and air dry it to obtain pretreated Pt / TiO2-NT composite material A; (2) Immerse the pretreated Pt / TiO2-NT composite material A in anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane for 20 minutes, then purge the soaked pretreated Pt / TiO2-NT composite material A with nitrogen for 20 minutes, then place it in an incubator and keep it at 55°C for 5 hours. After it cools naturally to room temperature, finally rinse it with anhydrous toluene and acetonitrile respectively. (3) The template mixture solution A was slowly and evenly dripped onto both sides of the pretreated Pt / TiO2-NT composite material B, and then inserted into a columnar quartz tube. Under a closed environment, it was purged with nitrogen for 30 minutes to obtain the pretreated Pt / TiO2-NT composite material C. (4) The pretreated Pt / TiO2-NT composite material C was subjected to polymerization reaction under 350nm ultraviolet light for 14 hours. After the reaction was completed, the product was washed with methanol solution until the molecular template could not be detected in the eluent. Finally, the MIP-Pt / TiO2-NT composite material was prepared.

[0046] Example 2: A method for preparing a composite material for photocatalytic degradation of PFOA:

[0047] Step 1: (1) The titanium foil was ultrasonically cleaned with acetone and deionized water for 20 minutes in sequence; (2) In a cylindrical electrochemical reactor with DC power supply, the cleaned titanium foil was used as the anode and the nickel sheet was used as the cathode. The anode and cathode were inserted into an electrolyte prepared by mixing 0.085 mol / L ethylene glycol and 0.5 mol / L ammonium fluoride. The mixture was magnetically stirred at 20°C and a constant voltage of 20V was applied for anodic oxidation. After 5 hours of reaction, the anode was rinsed with deionized water 3 times. After drying, it was placed in a muffle furnace and annealed at 500°C for 0.5 hours under nitrogen protection to obtain highly ordered and vertically arranged TiO2-NT.

[0048] Step 2: (1) Immerse 40g of TiO2-NT in 10wt% oxalic acid solution at 100℃, acid wash for 1 hour, take it out and wash it once with deionized water to obtain pretreated TiO2-NT; (2) Add the pretreated TiO2-NT to deionized water, and disperse it by ultrasonication for 30 minutes to prepare a TiO2-NT suspension of 14g / L; (3) Add 2mL of 8mM chloroplatinic acid solution and 10mL of polyethylene glycol to the TiO2-NT suspension, mix and stir for 30 minutes to obtain a reaction solution; (4) Add 2mL of 0.5g / L potassium borohydride solution to the reaction solution, and after the addition is complete, continue the reaction for 15 minutes to end the reaction. After filtration and washing, dry at 110℃ to obtain Pt / TiO2-NT composite material;

[0049] Step 3: Apply a 15wt% ammonium perrhenate solution to both sides of the Pt / TiO2-NT composite material, sinter at 440℃ for 5 minutes, and repeat the coating-sintering process twice to obtain the modified Pt / TiO2-NT composite material.

[0050] Step 4: (1) Soak the modified Pt / TiO2-NT composite material in 0.8 mol / L sodium hydroxide solution for 40 minutes, then take it out, rinse it with deionized water and air dry it to obtain pretreated Pt / TiO2-NT composite material A; (2) Immerse the pretreated Pt / TiO2-NT composite material A in anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane for 20 minutes, then purge the soaked pretreated Pt / TiO2-NT composite material A with nitrogen for 20 minutes, then place it in an incubator and keep it at 55°C for 5 hours. After it cools naturally to room temperature, finally rinse it with anhydrous toluene and acetonitrile respectively. (3) The template mixture solution A was slowly and evenly dripped onto both sides of the pretreated Pt / TiO2-NT composite material B, and then inserted into a columnar quartz tube. Under a closed environment, it was purged with nitrogen for 30 minutes to obtain the pretreated Pt / TiO2-NT composite material C. (4) The pretreated Pt / TiO2-NT composite material C was subjected to polymerization reaction under 350nm ultraviolet light for 14 hours. After the reaction was completed, the product was washed with methanol solution until the molecular template could not be detected in the eluent. Finally, the MIP-Pt / TiO2-NT composite material was prepared.

[0051] Example 3: A method for preparing a composite material for photocatalytic degradation of PFOA:

[0052] Step 1: (1) The titanium foil was ultrasonically cleaned with acetone and deionized water for 40 minutes in sequence; (2) In a cylindrical electrochemical reactor with DC power supply, the cleaned titanium foil was used as the anode and the nickel sheet was used as the cathode. The anode and cathode were inserted into an electrolyte prepared by mixing 0.085 mol / L ethylene glycol and 0.5 mol / L ammonium fluoride. The mixture was magnetically stirred at 20°C and a constant voltage of 20V was applied for anodic oxidation. After 8 hours of reaction, the anode was rinsed with deionized water 3 times. After drying, it was placed in a muffle furnace and annealed at 650°C for 2 hours under nitrogen protection to obtain highly ordered and vertically arranged TiO2-NT.

[0053] Step 2: (1) Immerse 40g of TiO2-NT in 10wt% oxalic acid solution at 100℃, acid wash for 1 hour, take it out and wash it once with deionized water to obtain pretreated TiO2-NT; (2) Add the pretreated TiO2-NT to deionized water, disperse it by ultrasonication for 30 minutes, and prepare a TiO2-NT suspension of 14g / L; (3) Add 2mL of 15mM chloroplatinic acid solution and 10mL of polyethylene glycol to the TiO2-NT suspension, mix and stir for 30 minutes to obtain a reaction solution; (4) Add 2mL of 1.5g / L potassium borohydride solution to the reaction solution, and after the addition is complete, continue the reaction for 15 minutes to end the reaction. After filtration and washing, dry at 110℃ to obtain Pt / TiO2-NT composite material;

[0054] Step 3: Apply a 15wt% ammonium perrhenate solution to both sides of the Pt / TiO2-NT composite material, sinter at 440℃ for 5 minutes, and repeat the coating-sintering process twice to obtain the modified Pt / TiO2-NT composite material.

[0055] Step 4: (1) Soak the modified Pt / TiO2-NT composite material in 0.8 mol / L sodium hydroxide solution for 40 minutes, then take it out, rinse it with deionized water and air dry it to obtain pretreated Pt / TiO2-NT composite material A; (2) Immerse the pretreated Pt / TiO2-NT composite material A in anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane for 20 minutes, then purge the soaked pretreated Pt / TiO2-NT composite material A with nitrogen for 20 minutes, then place it in an incubator and keep it at 55°C for 5 hours. After it cools naturally to room temperature, finally rinse it with anhydrous toluene and acetonitrile respectively. (3) The template mixture solution A was slowly and evenly dripped onto both sides of the pretreated Pt / TiO2-NT composite material B, and then inserted into a columnar quartz tube. Under a closed environment, it was purged with nitrogen for 30 minutes to obtain the pretreated Pt / TiO2-NT composite material C. (4) The pretreated Pt / TiO2-NT composite material C was subjected to polymerization reaction under 350nm ultraviolet light for 14 hours. After the reaction was completed, the product was washed with methanol solution until the molecular template could not be detected in the eluent. Finally, the MIP-Pt / TiO2-NT composite material was prepared.

[0056] Comparative Example 1: Template mixture solution B was used, and other procedures were the same as in Example 1; specifically:

[0057] Step 4: (1) Soak the modified Pt / TiO2-NT composite material in 0.8 mol / L sodium hydroxide solution for 40 minutes, then take it out, rinse it with deionized water and air dry it to obtain pretreated Pt / TiO2-NT composite material A; (2) Immerse the pretreated Pt / TiO2-NT composite material A in anhydrous toluene solution containing 3-aminopropyltriethoxysilane and 3-methacryloyloxypropyltrimethoxysilane for 20 minutes, then purge the soaked pretreated Pt / TiO2-NT composite material A with nitrogen for 20 minutes, then place it in an incubator and keep it at 55°C for 5 hours. After it cools naturally to room temperature, finally rinse it with anhydrous toluene and acetonitrile respectively. Wash it and dry it under nitrogen to obtain pretreated Pt / TiO2-NT composite material B; (3) Slowly and evenly drop template mixture B onto both sides of pretreated Pt / TiO2-NT composite material B, then insert it into a columnar quartz tube, and purge it with nitrogen for 30 minutes under a closed environment to obtain pretreated Pt / TiO2-NT composite material C; (4) Perform polymerization reaction on pretreated Pt / TiO2-NT composite material C under 350nm ultraviolet light for 14 hours. After the reaction is completed, wash the product with methanol solution until no molecular template can be detected in the eluent, and finally prepare MIP-Pt / TiO2-NT composite material;

[0058] Comparative Example 2: Pt / TiO2-NT composite material was prepared by modifying TiO2-NT with Pt only; the specific steps were the same as in Example 1, Step 1 and Step 2.

[0059] Comparative Example 3: Step 3 is not performed, i.e., rhenium heptaoxide is not introduced; otherwise, it is the same as Example 1.

[0060] Performance testing: The photocatalytic materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested using a photocatalytic reactor. The photocatalytic reactor was a 200mL open quartz beaker with a cooling water jacket (inner diameter 60mm, outer diameter 80mm); a high-pressure mercury lamp (125W, center wavelength 365nm, light intensity 5.3mW·cm²) was used. 2 The PFOA solution was placed parallel to the photocatalytic reactor for irradiation. The same mass of different photocatalysts was added to 150 mL of PFOA solution (50 mg / L). The irradiation reaction was carried out for 8 hours, and the change in PFOA concentration was finally measured.

[0061] Table 1

[0062] Example Degradation efficiency (%) Example 1 95.0 Example 2 92.3 Example 3 93.8 Comparative Example 1 83.4 Comparative Example 2 63.0 Comparative Example 3 90.6

[0063] Results Analysis: As can be seen from the table above, the photocatalytic material prepared by modifying TiO2-NT with Pt, Tc2O7 and MIP produced in this invention has high selective adsorption and photodegradation efficiency of PFOA, reaching a maximum degradation efficiency of 95%, which is much higher than that of the photocatalytic material prepared by modifying TiO2-NT with Pt alone.

[0064] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite material for photocatalytic degradation of PFOA, characterized by: The method comprises the following steps: Step one: using the cleaned titanium foil as anode, nickel sheet as cathode, inserting them into electrolyte, applying voltage to carry out anodic oxidation treatment, and finally annealing to obtain TiO2-NT; Step two: first pretreating TiO2-NT, then preparing TiO2-NT suspension, adding chloroplatinic acid and dispersing agent, stirring and mixing, adding potassium borohydride to react, and finally filtering, washing and drying to obtain Pt / TiO2-NT composite material; Step three: coating ammonium perrhenate on Pt / TiO2-NT composite material, and then sintering, repeating 1-2 times to obtain modified Pt / TiO2-NT composite material; Step four: preparing MIP-Pt / TiO2-NT composite material by molecular imprinting technology; The specific process of step one is as follows: (1) first cleaning the titanium foil with acetone and deionized water by ultrasonic cleaning for 20-40 minutes; (2) in a cylindrical electrochemical reactor with direct current power supply, using the cleaned titanium foil as anode and nickel sheet as cathode, inserting them into electrolyte; stirring under magnetic force at room temperature, and applying constant voltage of 20-50V, after anodic oxidation for 5-8 hours, rinsing the anode with deionized water for 1-3 times, and annealing to obtain highly ordered and vertically arranged TiO2-NT; The electrolyte is prepared by mixing ethylene glycol and ammonium fluoride; the concentration of ethylene glycol is 0.085mol / L, and the concentration of ammonium fluoride is 0.5mol / L; Annealing: annealing temperature: 500-650℃, annealing time: 0.5-2 hours; The specific process of step two is as follows: (1) immersing TiO2-NT into 10wt% oxalic acid solution at 100-110℃, and after acid washing for 1-3 hours, taking out and washing with deionized water for 1-3 times to obtain pretreated TiO2-NT; (2) adding pretreated TiO2-NT into deionized water, and dispersing by ultrasonic for 20-40 minutes to prepare 14g / L TiO2-NT suspension; (3) adding chloroplatinic acid solution and dispersing agent into TiO2-NT suspension, and mixing and stirring for 10-30 minutes to obtain reaction solution; (4) adding potassium borohydride solution dropwise into the reaction solution, continuing to react for 10-15 minutes after dropwise addition is completed, and then filtering, washing and drying to obtain Pt / TiO2-NT composite material; The concentration of chloroplatinic acid solution is 8-15mM, and the concentration of potassium borohydride solution is 0.5-1.5g / L; the content ratio of Pt / Ti is 1.0-1.5at%; The specific process of step three is as follows: coating 10-15wt% ammonium perrhenate solution on both sides of Pt / TiO2-NT composite material, sintering at 420-500℃ for 5-10 minutes, and repeating the coating-sintering process for 1-2 times to obtain modified Pt / TiO2-NT composite material; The specific process of step four is as follows: (1) The modified Pt / TiO2-NT composite material is soaked in a 0.8 mol / L sodium hydroxide solution for 20-40 minutes, then taken out, washed, and dried to obtain a pretreated Pt / TiO2-NT composite material A; (2) The pretreated Pt / TiO2-NT composite material A is immersed in anhydrous toluene solution containing 3-aminopropyl triethoxysilane and 3-methacryloyloxypropyl trimethoxysilane, soaked for 10-30 minutes, then the pretreated Pt / TiO2-NT composite material A after soaking is purged with nitrogen for 10-30 minutes, then it is placed in an incubator and incubated at 50-60°C for 3-6 hours, then it is naturally cooled to room temperature, finally it is washed with toluene and acetonitrile respectively and dried in a nitrogen environment to obtain a pretreated Pt / TiO2-NT composite material B; (3) The PFOA template is added to a mixed solution containing methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile, ultrasonically dispersed for 5-15 minutes, then slowly and uniformly dropped on both sides of the pretreated Pt / TiO2-NT composite material B, then inserted into a cylindrical quartz tube, purged with nitrogen for 10-40 minutes in a closed environment to obtain a pretreated Pt / TiO2-NT composite material C; (4) The pretreated Pt / TiO2-NT composite material C is subjected to a polymerization reaction under irradiation of 350 nm ultraviolet light for 10-15 hours, after the reaction is completed, the product is washed with a methanol solution until no molecular template is detected in the eluent, and finally a MIP-Pt / TiO2-NT composite material is prepared.

2. The preparation method of the composite material for photocatalytic degradation of PFOA according to claim 1, characterized in that: In the anhydrous toluene solution containing 3-aminopropyl triethoxysilane and 3-methacryloyloxypropyl trimethoxysilane, the volume ratio of 3-aminopropyl triethoxysilane, 3-methacryloyloxypropyl trimethoxysilane, and anhydrous toluene is 1:1:

48.

3. The preparation method of the composite material for photocatalytic degradation of PFOA according to claim 1, characterized in that: In the mixed solution prepared from the template, methanol / acetonitrile solution, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile, the concentration of the template is 0.02 mol / L, the concentration of acrylamide is 0.5 mol / L, the concentration of ethylene glycol dimethacrylate is 1.5 mol / L, the concentration of azobisisobutyronitrile is 0.05 mol / L, and the methanol / acetonitrile solution is prepared by mixing methanol and acetonitrile at a volume ratio of 1:

1.

4. The MIP-Pt / TiO2-NT composite material prepared by the preparation method of the composite material for photocatalytic degradation of PFOA according to any one of claims 1-3.

5. Use of MIP-Pt / TiO2-NT composite material, characterized in that: The MIP-Pt / TiO2-NT composite material according to claim 4 is used as a photocatalytic material for degrading PFOA.