Preparation method and application of BiOI embedded bismuth-based surface molecular imprinting photocatalyst

Abstract

The invention discloses a preparation method and application of a BiOI embedded bismuth-based surface molecular imprinting photocatalyst, which comprises the following steps: dissolving template molecule citalopram and functional monomer 2-acrylamide-2-methylpropanesulfonic acid in an ethanol solvent, pre-polymerizing at 20-40 DEG C for 2-8 hours, adding a carrier BiOIO3 nanosheet and bismuth nitrate pentahydrate, and carrying out ultrasonic full dispersion and dissolution, thereby obtaining the BiOI embedded bismuth-based surface molecular imprinting photocatalyst. The preparation method comprises the following steps: adding a bismuth nitrate solution into a reaction kettle, dropwise adding a KI solution, stirring and mixing for 1-3 hours, adding ethylene glycol dimethacrylate serving as a cross-linking agent and azodiisobutyronitrile serving as an initiator, carrying out ultrasonic treatment and nitrogen protection, carrying out thermal polymerization at 50-70 DEG C for 20-30 hours, and eluting and drying to obtain the BiOI embedded bismuth-based surface molecular imprinting photocatalyst. The capacity of selectively adsorbing and degrading a target object citalopram in an aqueous solution of the prepared imprinted photocatalyst is obviously superior to that of a traditional surface molecular imprinting photocatalyst, and the imprinted photocatalyst can be used for efficient selective photocatalytic removal of citalopram in an actual water sample.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of functional high molecular polymers, and specifically relates to a preparation method and application of a BiOI embedded bismuth-based surface molecular imprinting photocatalyst. Background Art

[0002] Heterogeneous photocatalysis is a completely green advanced oxidation technology that can rapidly oxidize and decompose a variety of pollutants in water without selectivity. However, the active species produced by photocatalysis have a short life span and are non-selective. In actual water bodies, pollutants are complex in composition, and high concentrations of non-toxic soluble organic matter and various inorganic ions often coexist with low concentrations of target substances. The coexisting pollutants will form competitive adsorption on the catalyst surface and be preferentially degraded, resulting in a large number of active species being ineffectively consumed. The number of active species allocated to target pollutants is limited, resulting in poor removal effect.

[0003] Molecularly imprinted polymers (MIPs) are adsorbent materials with selective recognition capabilities. Under the induction of template molecules, the material copolymerizes with functional monomers to form imprinted cavities containing "specific recognition sites". The dual effects of synergistic functional monomer binding sites and structural complementary cavities can achieve selective adsorption of target pollutants in complex water environments, thereby achieving the purpose of separating and enriching low-concentration target pollutants.

[0004] Existing studies have shown that combining molecular imprinting polymers with photocatalytic materials and constructing molecular recognition cavities near the catalytic active sites on the surface of the photocatalyst can enable the photocatalyst to accurately identify target pollutants under complex matrix conditions and enrich the target pollutants near the catalytic active sites. Under light conditions, the various active species produced by the catalyst can concentrate on attacking the target pollutants, efficiently degrading toxic chemicals into non-toxic products, and achieving the complete removal of target pollutants in a preferential manner.

[0005] Patent document with publication number CN111234295B discloses a method for preparing a molecular imprinted photocatalytic material, comprising mixing a template molecule, a functional monomer and a porogen to carry out a prepolymerization reaction to obtain a prepolymer; mixing the prepolymer, a crosslinking agent, an initiator and BiOBr, and carrying out a polymerization reaction under protective atmosphere conditions to obtain a polymer; eluting the polymer to obtain the molecular imprinted photocatalytic material, the elution method being calcination, the calcination temperature being 400~500℃, and the calcination time being 2~4h. The patent document has the following three deficiencies: First, the solvent used in the preparation process is non-polar solvent acetonitrile or methanol. Although these solvents are commonly used solvents in the molecular imprinting preparation process, they are not environmentally friendly and are prone to secondary pollution. Using polar solvent ethanol as a solvent is relatively green, but polar solvent ethanol usually affects the combination of functional monomers and template molecules, and it is not easy to prepare molecular imprinting polymers; second, the calcination elution method is used in the process of removing the template molecules, which requires a relatively high temperature and consumes a lot of energy. The elution effect with methanol is not good; third, from the analysis of the selectivity effect, the selectivity of the prepared molecular imprinting polymer is not obvious enough, which may be because the molecular structure of the imprinting site is destroyed during the calcination process, so that the imprinting cavity cannot match the structure of the target pollutant, or the traditional chain functional monomer will form more non-imprinting areas due to the steric hindrance effect during the polymerization process, resulting in the adsorption of non-target pollutants.

[0006] During the preparation of molecular imprinted polymers, the elution effect of the template molecules directly affects the adsorption performance and selectivity of the molecular imprinted catalytic material. The high-temperature calcination method used in the above patent literature to elute the template molecules not only consumes a lot of energy, but also causes the molecular imprinted polymer to degrade due to excessively high temperature, thereby destroying the imprinted cavity structure, resulting in a mismatch between the imprinted cavity and the spatial structure of the template pollutant, and thus causing a decrease in selectivity. In the process of preparing MIPs, it is also very important to choose a suitable solvent, which not only affects the effect of the polymerization reaction, but also affects the performance of the final product MIPs. Considering environmental protection and production safety issues, the selected solvent is preferably low in toxicity to reduce the impact on the environment. During the preparation of molecular imprinted polymers, the functional monomers and template molecules are mainly combined through hydrogen bonds. The stronger the polarity of the solvent, the less conducive it is to form hydrogen bonds. Therefore, non-polar solvents such as acetonitrile or methanol are currently commonly used as solvents, but their disadvantages are high toxicity and environmental unfriendliness. The polar solvent ethanol is relatively green, but ethanol is unfavorable for many molecular imprintings (especially non-covalent imprintings) because it inhibits the formation of hydrogen bonds between monomers and templates, which is also one of the difficulties faced by molecular imprinting technology.

[0007] Although surface imprinted photocatalysts have achieved certain results on a laboratory scale, they have inherent defects in the selective degradation of pollutants in practical applications. First, traditional surface imprinted photocatalysts belong to adsorption-assisted selective degradation. The coating of imprinted polymers usually produces additional adsorption sites to achieve selective adsorption of target pollutants, while the target pollutants are usually separated from the catalytic sites. The long site distance is not conducive to selective oxidation. The life span of photoactive species is extremely short, and long-distance transmission causes their ineffective consumption, resulting in a significant reduction in their utilization rate. Secondly, the imprinted layer covering the catalytic active sites will cause light scattering, reducing light absorption and photocatalytic ability. Finally, traditional imprinted polymers produce more non-imprinted areas during the polymerization of chain functional monomers. The imprinted cavity does not match the spatial structure of the template pollutant well and is easily interfered by small molecules or structural analogs. The resulting nonspecific adsorption and competition between active substances will reduce the degradation efficiency of the target pollutants. Synthesizing BiOI and the imprinted polymer on the surface of the imprinted catalyst simultaneously is expected to achieve effective fusion of the imprinted sites and catalytic sites, reducing the problem of reduced catalytic performance of the photocatalyst due to the coverage of the imprinted layer. At the same time, the embedding of BiOI in the imprinted polymer may improve the spatial structure of the imprinted cavity, thereby improving the selectivity of the target. There is currently no relevant research on this issue. Summary of the invention

[0008] The technical problem solved by the present invention is to provide a method for preparing a BiOI-embedded bismuth-based surface molecular imprinting photocatalyst. The BiOI-embedded bismuth-based surface molecular imprinting photocatalyst prepared by the method has a strong ability to selectively adsorb the target substance citalopram in an aqueous solution, and citalopram is preferentially and rapidly degraded under light conditions, and can be used for the selective photocatalytic removal of citalopram in actual water samples.

[0009] The present invention adopts the following technical scheme to solve the above technical problems. A preparation method of a BiOI embedded bismuth-based surface molecular imprinting photocatalyst is characterized in that the specific process is as follows: dissolving a template molecule citalopram and a functional monomer 2-acrylamide-2-methylpropanesulfonic acid into an ethanol solvent, prepolymerizing at 20-40° C. for 2-8 h, then adding a carrier BiOIO3 nanosheet and bismuth nitrate pentahydrate for ultrasonic full dispersion and dissolution, then dripping a KI solution and stirring and mixing for 1-3 h, then adding a crosslinking agent ethylene glycol dimethacrylate and an initiator azobisisobutyronitrile, after ultrasonic and nitrogen protection, thermally polymerizing at 50-70° C. for 20-30 h, eluting and drying to obtain a BiOI embedded bismuth-based surface molecular imprinting photocatalyst; The BiOIO3 nanosheets are synthesized by a hydrothermal method. The specific synthesis process is: bismuth nitrate pentahydrate and potassium iodate are dissolved in pure water, stirred for 1 to 2 hours, and then placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 130 to 180° C. for 3 to 8 hours. The BiOIO3 nanosheets are washed with water and ethanol several times and dried to obtain the BiOIO3 nanosheets.

[0010] It is further defined that the molar ratio of the template molecule, the functional monomer, the cross-linking agent and the initiator is 1:2~6:1~16:1; the molar ratio of the template molecule, bismuth nitrate pentahydrate and KI is 1:2~3:2~64.

[0011] It is further defined that the elution process is specifically to use a mixture of methanol and acetic acid in a volume ratio of 9:1 for Soxhlet extraction for 48 hours.

[0012] The BiOI embedded bismuth-based surface molecular imprinting photocatalyst of the present invention is used for the selective photocatalytic removal of venlafaxine in actual water samples.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention adopts a method of synchronously synthesizing BiOI and a surface imprinted polymer to prepare a citalopram surface imprinted photocatalyst. By regulating the BiOI content, the catalyst has the properties of high selectivity, good photocatalytic performance, large adsorption capacity and strong anti-interference ability.

[0014] 2. The present invention adopts ethanol as the preparation solvent, which reduces the secondary pollution to the environment caused by non-polar solvents such as acetonitrile and methanol.

[0015] 3. The present invention adopts the method of synchronous synthesis of BiOI and imprinted polymer and synchronous coating of BiOIO3 to embed the photocatalyst BiOI into the imprinted polymer, and at the same time form a heterojunction with the carrier BiOIO3, which can not only make the photocatalyst closely combined with the adsorption site, reduce the mass transfer distance, and improve the utilization rate of photoactive species, but also enhance the catalyst's ability to absorb light, extending from ultraviolet light to visible light. In addition, during the synchronous synthesis of BiOI and imprinted polymer, BiOI also participates in the formation of imprinted sites and fills the non-imprinted area, so that the imprinted cavity is more matched with the spatial structure of the target molecule, and the selectivity is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the synthesis route of the carrier BiOIO3 and the imprinted photocatalyst EMI-Bi / Bi in the present invention.

[0017] Figure 2 It is a scanning electron microscope image of the carrier, the imprinted photocatalyst and the non-imprinted photocatalyst in the present invention.

[0018] Figure 3 It is the adsorption kinetics diagram of the imprinted photocatalyst and the non-imprinted photocatalyst of the present invention.

[0019] Figure 4 It is the adsorption isotherm diagram of the imprinted photocatalyst and the non-imprinted photocatalyst of the present invention.

[0020] Figure 5 This is a graph showing the change in removal rate of citalopram in municipal sewage by the imprinted photocatalyst and the photocatalyst carrier of the present invention over time. DETAILED DESCRIPTION

[0021] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example 1

[0022] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 130°C for 3 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0023] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.2 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 20°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 2

[0024] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 2 h, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 130 °C for 3 h. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0025] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.2 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 20°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 3

[0026] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 3 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0027] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.2 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 20°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 4

[0028] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0029] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.2 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 20°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 5

[0030] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0031] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 20°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 6

[0032] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0033] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 2 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 7

[0034] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0035] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.2 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 8

[0036] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0037] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.2 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 9

[0038] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0039] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.001 mmol KI was added dropwise and stirred for 1 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 10

[0040] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0041] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.001 mmol KI was added dropwise and stirred for 3 h. Then, 0.2 mmol of a crosslinker, ethylene glycol dimethacrylate, and 0.1 mmol of an initiator, azobisisobutyronitrile, were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Embodiment 11

[0042] Preparation of BiOIO3 nanosheets: 0.5 g of bismuth nitrate pentahydrate and 0.2 g of potassium iodate were dissolved in pure water, stirred for 1 hour, and placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 hours. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0043] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.001 mmol KI was added dropwise and stirred for 3 h. Then, 1.6 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 50°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 12

[0044] Preparation of BiOIO3 nanosheets: Bismuth nitrate pentahydrate and potassium iodate were dissolved in pure water, stirred for 1 h, and then placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 h. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0045] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.001 mmol KI was added dropwise and stirred for 3 h. Then, 1.6 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 70°C for 20 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Example 13

[0046] Preparation of BiOIO3 nanosheets: Bismuth nitrate pentahydrate and potassium iodate were dissolved in pure water, stirred for 1 h, and then placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 180°C for 8 h. The BiOIO3 nanosheets were obtained by washing with water and ethanol several times and drying.

[0047] Preparation of imprinted photocatalyst: Using 20 mL of ethanol as solvent, 0.1 mmol of citalopram (template molecule) and 0.6 mmol of 2-acrylamide-2-methylpropanesulfonic acid (functional monomer) were prepolymerized at 40°C for 8 h, and then 0.10 g of the above-mentioned homemade BiOIO3 nanosheets (carrier) and 0.3 mmol of bismuth nitrate pentahydrate were added. After ultrasonic dispersion and dissolution, 10 mL of an aqueous solution containing 0.001 mmol KI was added dropwise and stirred for 3 h. Then, 1.6 mmol of a cross-linking agent ethylene glycol dimethacrylate and 0.1 mmol of an initiator azobisisobutyronitrile were added. After ultrasonication and N2 filling, the product was thermally initiated and polymerized at 70°C for 30 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture with a volume ratio of 9:1 for 48 h and then vacuum dried to obtain the imprinted photocatalyst. Embodiment 14

[0048] 20 mg of the imprinted photocatalyst (EMI-Bi / Bi) and the non-imprinted photocatalyst (ENI-Bi / Bi) prepared in Example 1 were mixed with 50 mL and 20 mg L -1 The mixture was mixed with a Citalopram aqueous solution and adsorbed at room temperature for a certain period of time (0-80 min). The supernatant was taken and the absorbance at 238 nm was measured by UV spectrophotometer. Figure 3 shown. Embodiment 15

[0049] 20 mg of the imprinted photocatalyst (EMI-Bi / Bi) and the non-imprinted photocatalyst (ENI-Bi / Bi) prepared in Example 1 were mixed with 50 mL of a citalopram aqueous solution (0-100 mg L -1 ), after 80 min of oscillation adsorption at room temperature, the supernatant was taken and the absorbance value at 238 nm was measured by UV spectrophotometer. Figure 4 shown. Example 16

[0050] 20 mg of the imprinted photocatalyst (EMI-Bi / Bi), non-imprinted photocatalyst (ENI-Bi / Bi) and photocatalyst carrier (BiOIO3) prepared in Example 1 were dispersed in 50 mL of Citalopram (20 mg L -1 ) and humic acid (60 mgL -1 ) in a mixed aqueous solution, stirred for 40 min in dark conditions to ensure adsorption-desorption equilibrium, and continued stirring for 180 min under a 500 W xenon lamp. The concentration of citalopram in the solution was determined at regular intervals by high performance liquid chromatography. The results are shown in Figure 5 shown. Embodiment 17

[0051] The imprinted photocatalyst prepared in Example 1 was used for the photocatalytic degradation of citalopram in actual wastewater. The degradation results of the spiked experiment showed that the removal rate was greater than 90%. Under the same conditions, it was more than 17% higher than that of the traditional imprinted photocatalyst and more than 28% higher than that of the photocatalyst carrier. This shows that the obtained imprinted photocatalyst has good practicality for the degradation of venlafaxine. After 7 cycles of use, the adsorption amount of venlafaxine by the imprinted photocatalyst still reached 31 mg g -1 , the total removal rate still reached more than 83%, indicating that the obtained imprinted polymer has excellent regeneration adsorption performance and stability.

[0052] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a BiOI-embedded bismuth-based surface molecularly imprinted photocatalyst, characterized in that The specific process is as follows: the template molecule citalopram and the functional monomer 2-acrylamide-2-methylpropanesulfonic acid are dissolved in ethanol solvent, prepolymerized at 20-40℃ for 2-8 h, and then the carrier BiOIO3 nanosheets and bismuth nitrate pentahydrate are added and ultrasonically dispersed and dissolved, then KI solution is added dropwise and stirred for 1-3 h, and then the crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile are added, and after ultrasonic and nitrogen protection, thermal polymerization is performed at 50-70℃ for 20-30 h, and the BiOI embedded bismuth-based surface molecularly imprinted photocatalyst is obtained after elution and drying. The BiOIO3 nanosheets are synthesized by a hydrothermal method. The specific synthesis process is: bismuth nitrate pentahydrate and potassium iodate are dissolved in pure water, stirred for 1 to 2 hours, and then placed in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction at 130 to 180° C. for 3 to 8 hours. The BiOIO3 nanosheets are washed with water and ethanol several times and dried to obtain the BiOIO3 nanosheets.

2. The method for preparing the BiOI embedded bismuth-based surface molecularly imprinted photocatalyst according to claim 1, characterized in that: The molar ratio of the template molecule, the functional monomer, the crosslinking agent and the initiator is 1:2-6:1-16:1; the molar ratio of the template molecule, bismuth nitrate pentahydrate and KI is 1:2-3:2-64.

3. The method for preparing the BiOI embedded bismuth-based surface molecularly imprinted photocatalyst according to claim 1, characterized in that: The elution process specifically includes Soxhlet extraction for 48 h using a mixture of methanol and acetic acid in a volume ratio of 9:

1.

4. The preparation method of the BiOI embedded bismuth-based surface molecularly imprinted photocatalyst prepared according to any one of claims 1 to 3 is used for the selective photocatalytic removal of citalopram in actual water samples.

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