A bisphenol a molecularly imprinted blend membrane, its preparation method and application

Abstract

The application provides a bisphenol A molecular imprinting blend membrane and a preparation method and application thereof, and relates to the technical field of environmental materials.The SiO2 / PVDF blend membrane is prepared by modifying polyvinylidene fluoride (PVDF) membrane with hydrophilic, stable and anti-pollution nanometer silicon dioxide (SiO2), and the SiO2 / PVDF blend membrane is used as a substrate, bisphenol A is used as a template molecule, a functional monomer, a crosslinking agent and an initiator are combined, and the bisphenol A molecular imprinting blend membrane is prepared by using a precipitation polymerization method.The prepared bisphenol A molecular imprinting blend membrane is subjected to static adsorption and selective adsorption experiments to study adsorption equilibrium and selective recognition performance, and the results show that the prepared bisphenol A molecular imprinting blend membrane has high adsorption capacity and good bisphenol A molecular recognition performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental materials, in particular to a bisphenol A molecular imprinting blend film and a preparation method and application thereof. BACKGROUND

[0002] Bisphenol A (BPA) is commonly used in industry to synthesize polycarbonate and epoxy resin materials, and is ubiquitous in life, such as plastic bottles, medical devices and food packaging products. Therefore, it is easy to penetrate into the environment during use and disposal, and bisphenol A has been detected in water environment, animals and human bodies. Bisphenol A usually affects human metabolism, causing hormone secretion disorder, and even causing damage to the endocrine system, bones and brain. Its transformation products can also cause ecological damage. Therefore, it is necessary to develop effective technology for specific adsorption and removal of bisphenol A in the environment.

[0003] Membrane separation technology has been widely used in biotechnology, medicine, food industry, environmental protection, energy and many other fields due to its high efficiency, energy saving, environmental protection, convenient operation and environmental friendliness. It is a technology that can separate different liquid raw materials, allowing one or more substances to pass through, while separating other substances. It plays the functions of separation, separation and selective permeation. However, it still has certain limitations in technology. For example, traditional membranes can only separate a certain type of substance, and cannot efficiently and selectively separate a single substance.

[0004] In order to improve the selectivity of the membrane, the membrane separation technology is combined with the molecular imprinting technology to prepare a molecular imprinting composite membrane. The basic principle of traditional molecular imprinting technology (MIT) is that when the template molecule contacts with the functional monomer, multiple action sites are formed, and specific recognition sites are generated through the polymerization process; when the template molecule is removed, imprinting cavities matching the spatial configuration of the template molecule are formed in the polymer, and the cavities have selective recognition characteristics for the template molecule. There is no molecular imprinting composite membrane for specific adsorption of bisphenol A in the prior art. SUMMARY

[0005] The purpose of the present application is to provide a bisphenol A molecular imprinting blend film and a preparation method and application thereof. The bisphenol A molecular imprinting blend film prepared by the present application has good adsorption performance and selective recognition ability for bisphenol A.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical scheme:

[0007] The present application provides a preparation method of a bisphenol A molecular imprinting blend film, comprising the following steps:

[0008] The bisphenol A, the first organic solvent and the functional monomer are mixed to perform pre-assembly to obtain a pre-assembly system;

[0009] Mixing the pre-assembled system and the crosslinking agent and the second organic solvent to obtain a mixed solution;

[0010] Mixing the nanosilica powder, the polyvinylidene fluoride and the third organic solvent to obtain a casting solution; performing film formation on the casting solution to obtain a SiO2 / PVDF blend film;

[0011] Placing the SiO2 / PVDF blend film in the mixed solution, first performing prepolymerization, and then performing polymerization under the action of an initiator, taking out the film to elute bisphenol A, and obtaining a bisphenol A molecularly imprinted blend film.

[0012] Preferably, the functional monomer is N-isopropyl acrylamide.

[0013] Preferably, the mass ratio of the bisphenol A and the functional monomer is 0.97:0.9-1.0.

[0014] Preferably, the mass ratio of the nanosilica powder and the polyvinylidene fluoride is 1:20-40.

[0015] Preferably, the film formation is a phase inversion method.

[0016] Preferably, the prepolymerization temperature is 30-60℃; and the prepolymerization time is 0.5-2h.

[0017] Preferably, the polymerization temperature is 40-80℃; and the polymerization time is 24-48h.

[0018] Preferably, the first organic solvent and the second organic solvent independently comprise methanol, acetonitrile, ethanol or toluene; and the third organic solvent comprises N-methyl pyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide.

[0019] The application provides a bisphenol A molecularly imprinted blend film prepared by the preparation method.

[0020] The application provides application of the bisphenol A molecularly imprinted blend film in specific adsorption or separation of bisphenol A.

[0021] The application provides a preparation method of bisphenol A molecular imprinting blend membrane.

[0022] The application can significantly improve the hydrophilic property of the membrane by modifying the surface of the membrane with hydrophilic and stable SiO2, and reduce the membrane pollution, thereby greatly improving the comprehensive performance of the bisphenol A molecular imprinting blend membrane. The imprinting process of the application occurs on the surface of the matrix material of the PVDF membrane, thereby avoiding the problem that some template molecules cannot be eluted due to being embedded too deeply in the traditional method, and the bisphenol A molecular imprinting blend membrane obtained has high mechanical strength, high temperature resistance and non-damaged recognition points, and the non-specific adsorption is greatly reduced. The application combines the molecular imprinting technology and the membrane separation technology, and the bisphenol A molecular imprinting blend membrane obtained has the advantages of the molecular imprinting technology and the membrane separation technology, and has the advantages of large specific surface area of SiO2 and good stability of PVDF, and can realize good combination performance and selective recognition ability of bisphenol A. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The scanning electron microscope image of the PVDF membrane in the control example;

[0024] Figure 2 The scanning electron microscope image of the bisphenol A molecular imprinting blend membrane in Example 1;

[0025] Figure 3 The water contact angle comparison diagram of the PVDF membrane in the control example and the bisphenol A molecular imprinting blend membrane in Example 1;

[0026] Figure 4 The selective adsorption columnar diagram of the bisphenol A molecular imprinting blend membrane prepared in Example 3 and the non-molecular imprinting blend membrane prepared in Comparative Example 1;

[0027] Figure 5 The static adsorption curve diagram of the bisphenol A molecular imprinting blend membrane prepared in Example 3 and the non-molecular imprinting blend membrane prepared in Comparative Example 1. DETAILED DESCRIPTION

[0028] The application provides a preparation method of bisphenol A molecular imprinting blend membrane, comprising the following steps:

[0029] mixing bisphenol A (BPA), a first organic solvent and a functional monomer to obtain a pre-assembly system;

[0030] mixing the pre-assembly system, a crosslinking agent and a second organic solvent to obtain a mixed solution;

[0031] mixing nano-silica powder, polyvinylidene fluoride (PVDF) and a third organic solvent to obtain a casting solution; and performing film formation on the casting solution to obtain a SiO2 / PVDF blend film;

[0032] placing the SiO2 / PVDF blend film in the mixed solution, performing pre-polymerization first, and then performing polymerization under the action of an initiator, and taking out the film to elute bisphenol A, thereby obtaining a bisphenol A molecularly imprinted blend film.

[0033] In the present application, the first organic solvent preferably includes methanol, acetonitrile, ethanol or toluene, and more preferably acetonitrile. In the present application, the functional monomer is preferably N-isopropyl acrylamide (NIPAM). In the present application, the mass ratio of bisphenol A to the functional monomer is preferably 0.97:0.9-1.0, and more preferably 0.97:0.96. In the present application, the mixing of bisphenol A, the first organic solvent and the functional monomer preferably includes: placing bisphenol A in the first organic solvent, uniformly dispersing by ultrasonic, and then adding the functional monomer. In the present application, the concentration of bisphenol A in the first organic solvent is preferably 5.7-11.4 g / L, and more preferably 7.6 g / L.

[0034] In the present application, the temperature of the pre-assembly is preferably room temperature, and the time of the pre-assembly is preferably 8-15 h, and more preferably 10 h. In the present application, the pre-assembly is preferably performed under stirring, and the stirring rate is preferably 1000-1500 rpm, and more preferably 1200 rpm. In the present application, the pre-assembly is to make the template molecule bisphenol A and the functional monomer combine with each other to form multiple action points.

[0035] After obtaining the pre-assembled system, the pre-assembled system is mixed with a crosslinking agent and a second organic solvent to obtain a mixed solution. In the present application, the crosslinking agent is preferably ethylene glycol dimethacrylate (EGDMA). In the present application, the second organic solvent preferably includes methanol, acetonitrile, ethanol or toluene, and more preferably acetonitrile. In the present application, the mixing of the pre-assembled system with the crosslinking agent and the second organic solvent preferably includes dissolving the crosslinking agent in the second organic solvent and then mixing with the pre-assembled system. In the present application, the concentration of the crosslinking agent in the mixed solution is preferably 4.26-7.98 mol / L, and more preferably 5.32 mol / L. In the present application, the molar ratio of bisphenol A to crosslinking agent is preferably 1:4-12, and more preferably 1:10.

[0036] The present application mixes nano-silicon dioxide powder, polyvinylidene fluoride and a third organic solvent to obtain a casting solution; and performs film formation on the casting solution to obtain a SiO2 / PVDF blend film. In the present application, the preparation method of the nano-silicon dioxide powder preferably includes mixing ethanol, water and tetraethyl orthosilicate, adjusting the pH value of the solution to 2-4, performing a hydrolysis reaction to obtain a hydrolysis reaction system; adjusting the pH value of the hydrolysis reaction system to 7-9 to obtain a gel; and calcining the gel to obtain nano-silicon dioxide powder. In the present application, the ethanol is preferably anhydrous ethanol; and the water is preferably deionized water. In the present application, the volume ratio of the ethanol, water and tetraethyl orthosilicate is preferably 8-12:1-6:1, and more preferably 10:3:1. In the present application, the reagent used for adjusting the pH value of the solution is preferably ammonium chloride. In the present application, the temperature of the hydrolysis reaction is preferably 50-80℃, and more preferably 60℃; and the time of the hydrolysis reaction is preferably 0.5-2h, and more preferably 1h. In the present application, the reagent used for adjusting the pH value of the hydrolysis reaction system is preferably ammonia water; and the mass concentration of the ammonia water is preferably 25%. In the present application, the atmosphere of the calcination is preferably nitrogen; the temperature of the calcination is preferably 100-300℃, and more preferably 200℃; and the holding time is preferably 1.5-3h, and more preferably 2h. In the present application, the average particle size of the nano-silicon dioxide powder is preferably 300-500nm, and more preferably 400nm.

[0037] In the present application, the mass ratio of the nanosilica powder and polyvinylidene fluoride is preferably 1:20-40, more preferably 1:30. In the present application, the third organic solvent preferably comprises N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide, more preferably N,N-dimethylformamide (DMF). In the present application, the mixing of the nanosilica powder, polyvinylidene fluoride and third organic solvent preferably comprises: ultrasonic dispersion of polyvinylidene fluoride in the third organic solvent, and addition of the nanosilica powder. In the present application, the concentration of polyvinylidene fluoride in the third organic solvent is preferably 0.15-0.3 g / mL, more preferably 0.24 g / mL.

[0038] After obtaining the casting solution, the present application performs film formation on the casting solution to obtain a SiO2 / PVDF blend film. In the present application, the film formation is preferably phase inversion film formation. In the present application, the specific method of film formation preferably comprises: sealing the casting solution, mechanical stirring, standing to remove bubbles, pouring the casting solution on a glass plate, coating the entire glass plate with the casting solution using a doctor blade, immersing the glass plate in deionized water for phase inversion, removing the obtained film from the glass plate after solidification, and drying at room temperature to obtain a SiO2 / PVDF blend film. In the present application, the temperature of the mechanical stirring is preferably 50-80°C, more preferably 60°C; the time of the mechanical stirring is preferably 12-24 h, more preferably 12 h. In the present application, the thickness of the SiO2 / PVDF blend film is preferably 0.1-0.3 mm, more preferably 0.15 mm.

[0039] After obtaining the SiO2 / PVDF blend film and the mixed solution obtained by mixing the pre-assembly system, crosslinking agent and second organic solvent as described above, the present application places the SiO2 / PVDF blend film in the mixed solution, performs pre-polymerization, and then performs polymerization reaction under the action of an initiator to obtain a bisphenol A molecularly imprinted blend film by eluting bisphenol A from the film. In the present application, the mass ratio of the SiO2 / PVDF blend film and the mixed solution is preferably 1:230-250, more preferably 1:240.

[0040] In the present application, the temperature of the pre-polymerization is preferably 35-55°C, more preferably 50°C; the time of the pre-polymerization is preferably 0.5-2 h, more preferably 1 h. In the present application, the pre-polymerization is preferably performed in an oil bath. The pre-polymerization in the present application is to preliminarily crosslink and polymerize the crosslinking agent and the functional monomer.

[0041] In the present application, the initiator is preferably azobisisobutyronitrile (AIBN). In the present application, the mass ratio of bisphenol A and initiator is preferably 57:3-6, more preferably 57:5.

[0042] In the present application, the temperature of the polymerization reaction is preferably 40-80℃, more preferably 60℃; the time of the polymerization reaction is preferably 24-48h, more preferably 24h. In the present application, the polymerization reaction is preferably carried out in a nitrogen atmosphere. In the present application, the method for providing the nitrogen atmosphere preferably comprises: after the nitrogen is introduced to discharge the oxygen, the polymerization reaction is carried out under the sealed condition. In the present application, the time for introducing the nitrogen is preferably 10-30min, more preferably 20min. The present application preferably takes out the film after the polymerization reaction, and then washes the un-polymerized functional monomer and cross-linking agent with ethanol and water in sequence.

[0043] In the present application, the eluent for eluting bisphenol A is preferably a mixed solution of methanol and acetic acid. In the present application, the volume ratio of methanol to acetic acid in the mixed solution of methanol and acetic acid is preferably 9:1. The present application preferably elutes until there is no bisphenol A in the eluent.

[0044] The present application preferably washes the obtained film with methanol after the elution of bisphenol A until the washing liquid is neutral, and then vacuum dries to obtain the bisphenol A molecularly imprinted blended film. The present application uses methanol to wash and remove the acetic acid on the surface of the film. In the present application, the temperature of the vacuum drying is preferably 40℃; the time of the vacuum drying is preferably 12h.

[0045] The present application provides a bisphenol A molecularly imprinted blended film prepared by the preparation method described in the above technical solution, which comprises a SiO2 / PVDF blended film and a molecularly imprinted polymer loaded on the surface of the SiO2 / PVDF blended film.

[0046] The present application provides an application of the bisphenol A molecularly imprinted blended film described in the above technical solution in specific adsorption or separation of bisphenol A.

[0047] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0048] Embodiment 1

[0049] 0.228g of bisphenol A (BPA) was placed in 30mL of acetonitrile solvent and uniformly dispersed by ultrasonic dispersion. 0.226g of N-isopropyl acrylamide (NIPAM) was added to the solution, and the pre-assembly system was obtained after stirring and reacting at room temperature for 10h;

[0050] Mix 44 mL of anhydrous ethanol, 13.2 mL of deionized water and 4.4 mL of ethyl orthosilicate in a flask, and mix well. Add ammonium chloride to adjust the pH value of the solution to 3.0. After reacting at 60°C for 1 h, add ammonia water (25% by mass) dropwise to adjust the pH value to 8 to form a gel. After calcination at 200°C for 2 h, nano-silica powder is obtained.

[0051] Disperse 6 g of PVDF powder in 25 mL of N,N-dimethylformamide (DMF) by ultrasonic for 20 min, and add 0.2 g of the nano-silica powder to obtain a casting solution. Seal the casting solution, and mechanically stir at 60°C for 12 h. After standing and degassing, the casting solution is coated on a glass plate by a flat blade coater (set the speed of the coater to 1.8 m / min, and the thickness of the film to 0.15 mm). Then, the glass plate with the casting solution is subjected to a phase inversion process in water. After solidification, the obtained film is separated from the glass plate, and dried at room temperature to obtain a SiO2 / PVDF blend film.

[0052] Add 0.75 mL of a mixture of ethylene glycol dimethacrylate and 4 mL of acetonitrile to the pre-assembled system to obtain a mixed solution. Immerse the SiO2 / PVDF blend film in the mixed solution, and pre-polymerize at 50°C in an oil bath for 1 h. Then, slowly add 0.02 g of azobisisobutyronitrile to the mixed solution, and ultrasonically disperse. After purging with nitrogen for 20 min to remove oxygen, polymerize at 60°C for 24 h under sealed conditions. After the reaction is completed, the film is washed with ethanol and water in sequence to remove un-polymerized functional monomers and cross-linking agents.

[0053] Wash the film prepared above with a mixed solution of methanol and acetic acid to remove the template molecules, wherein the volume ratio of methanol to acetic acid is 9:1, until no bisphenol A is detected in the eluent. Then, wash the film with methanol until the washing solution is neutral. Dry the film at 40°C under vacuum for 12 h to obtain a bisphenol A molecularly imprinted blend film.

[0054] Perform an adsorption experiment on the bisphenol A molecularly imprinted blend film prepared above. Place a piece of the bisphenol A molecularly imprinted blend film in a 50 mg / L bisphenol A methanol solution, and perform water bath oscillation at 25°C. After 4 h, the adsorption is completed. The concentration of bisphenol A is determined by high performance liquid chromatography, and the adsorption capacity is calculated according to the experimental results. The experimental results show that the adsorption capacity of the bisphenol A molecularly imprinted blend film prepared in this example for bisphenol A is 13.4 mg / g.

[0055] Comparative Example

[0056] The preparation method is basically the same as that of Example 1, except that no nano-silica powder is added, and a PVDF film is obtained.

[0057] Figure 1The scanning electron microscope image of the PVDF membrane in the control example. From Figure 1 It can be seen that the membrane has a porous structure and the pores are uniformly distributed.

[0058] Figure 2 The scanning electron microscope image of the bisphenol A molecularly imprinted blended membrane in Example 1. From Figure 2 It can be seen that polymer particles are aggregated on the surface of the membrane, and the surface pores of the membrane are obviously reduced, indicating that the imprinted polymer is generated on the surface of the membrane, indicating that the imprinting process is successfully implemented on the PVDF membrane.

[0059] Figure 3 The water contact angle images of a, b of the PVDF membrane in the control example and the bisphenol A molecularly imprinted blended membrane in Example 1. When the water contact angle is less than 90°, the sample can be considered to be hydrophilic, and vice versa. Figure 3 a is the water contact angle image of the PVDF membrane. Due to the inherent hydrophobicity of the PVDF raw material, the contact angle of the pure PVDF membrane is larger. Figure 3 b is the water contact angle image of the bisphenol A molecularly imprinted blended membrane. It can be clearly seen that the water contact angle of the molecularly imprinted blended membrane is smaller than that of the PVDF membrane. Therefore, the imprinting process improves the hydrophilicity of the membrane and improves its anti-pollution ability, which is conducive to the rapid and specific separation of the membrane to bisphenol A.

[0060] Example 2

[0061] 0.228g of bisphenol A (BPA) was placed in 30mL of acetonitrile solvent and ultrasonically dispersed uniformly, 0.226g of N-isopropyl acrylamide (NIPAM) was added to the solution, and the pre-assembly system was obtained after stirring at room temperature for 10h;

[0062] 44mL of anhydrous ethanol, 13.2mL of deionized water and 4.4mL of tetraethyl orthosilicate were added to a flask and mixed uniformly, and ammonium chloride was appropriately added to adjust the pH value of the solution to 3.0, and then ammonia water (mass concentration of 25%) was added dropwise at a temperature of 60°C for 1h, and the pH value was adjusted to 8 to form a gel, and then calcined at 200°C for 2h to obtain nano-silicon dioxide powder;

[0063] 6g of PVDF powder was ultrasonically dispersed in 25mL of N,N-dimethylformamide (DMF) for 20min, and 0.2g of the nano-silicon dioxide powder was added to obtain a casting solution; the casting solution was sealed and mechanically stirred at 60°C for 12h, and then left to degas, and then scraped with a flat plate to form a film (the speed of the film scraping machine was set to 1.8m / min, and the film thickness was 0.15mm), and then the glass plate with the casting solution was subjected to a phase inversion process in water, and then the obtained membrane was separated from the glass plate and dried at room temperature to obtain a SiO2 / PVDF blended membrane;

[0064] To the pre-assembly system, 1.50 mL of a mixture of ethylene glycol dimethacrylate and 4 mL of acetonitrile was added to obtain a mixed solution; the SiO2 / PVDF blended membrane was immersed in the mixed solution, and the oil bath was warmed to 50°C for pre-polymerization for 1 h; then, 0.02 g of azobisisobutyronitrile was slowly added to the mixed solution, ultrasonically dispersed uniformly, and after nitrogen was introduced for 20 min and oxygen was exhausted, the polymerization reaction was carried out at 60°C under sealed conditions for 24 h; after the reaction was completed, the membrane was taken out and washed with ethanol and water in sequence to remove the un-polymerized functional monomer and cross-linking agent;

[0065] The above-prepared membrane was washed with a mixed solution of methanol and acetic acid to elute the template molecules, the volume ratio of methanol to acetic acid in the mixed solution was 9:1, until no bisphenol A was present in the obtained eluate; then, the obtained membrane was washed with methanol until the washing liquid was neutral; and the membrane was dried under vacuum at 40°C for 12 h to obtain a bisphenol A molecularly imprinted blended membrane.

[0066] The above-prepared bisphenol A molecularly imprinted blended membrane was subjected to an adsorption experiment: a piece of bisphenol A molecularly imprinted blended membrane was placed in a 50 mg / L concentration bisphenol A methanol solution, and water bath oscillation was carried out at 25°C; after 4 h, the adsorption was completed, the concentration of bisphenol A was determined by high performance liquid chromatography, and the adsorption capacity was calculated according to the experimental results. The experimental results showed that the adsorption capacity of the bisphenol A molecularly imprinted blended membrane prepared in this embodiment for bisphenol A was 16.2 mg / g.

[0067] Example 3

[0068] 0.228 g of bisphenol A (BPA) was placed in 30 mL of acetonitrile solvent and ultrasonically dispersed uniformly; 0.226 g of N-isopropyl acrylamide (NIPAM) was added to the solution, and after stirring at room temperature for 10 h, a pre-assembly system was obtained;

[0069] 44 mL of anhydrous ethanol, 13.2 mL of deionized water and 4.4 mL of tetraethyl orthosilicate were added to a flask and mixed uniformly; ammonium chloride was appropriately added to adjust the pH value of the solution to 3.0; after reaction at a temperature of 60°C for 1 h, ammonia water (25% by mass) was added dropwise to adjust the pH value to 8 to form a gel; the gel was calcined at 200°C for 2 h to obtain nano-silicon dioxide powder;

[0070] 6 g of PVDF powder was ultrasonically dispersed in 25 mL of N,N-dimethylformamide (DMF) for 20 min, and 0.2 g of the nano-silicon dioxide powder was added to obtain a casting solution; the casting solution was sealed and mechanically stirred at 60°C for 12 h; after standing and degassing, the casting solution was cast by a flat plate casting machine (the speed of the casting machine was set to 1.8 m / min, and the thickness of the membrane was 0.15 mm); then, the glass plate with the casting solution was subjected to a phase inversion process in water, and after solidification, the obtained membrane was separated from the glass plate and air-dried at room temperature to obtain a SiO2 / PVDF blended membrane.

[0071] To the pre-assembly system, 1.88 mL of a mixture of ethylene glycol dimethacrylate and 4 mL of acetonitrile was added to obtain a mixed solution; the SiO2 / PVDF blended membrane was immersed in the mixed solution, and the oil bath was heated to 50°C for pre-polymerization for 1 h; then, 0.02 g of azobisisobutyronitrile was slowly added to the mixed solution and uniformly dispersed by ultrasonic, and after nitrogen was introduced for 20 min and oxygen was exhausted, the polymerization reaction was carried out at 60°C under sealed conditions for 24 h; after the reaction was completed, the membrane was taken out and washed with ethanol and water to remove un-polymerized functional monomers and cross-linking agents;

[0072] The above-prepared membrane was washed with a mixed solution of methanol and acetic acid to elute the template molecules, the volume ratio of methanol to acetic acid in the mixed solution was 9:1, until no bisphenol A was present in the eluate, and then the obtained membrane was washed with methanol until the washing liquid was neutral; the membrane was dried at 40°C under vacuum for 12 h to obtain a bisphenol A molecularly imprinted blended membrane.

[0073] The above-prepared bisphenol A molecularly imprinted blended membrane was subjected to an adsorption experiment: a piece of bisphenol A molecularly imprinted blended membrane was placed in a 50 mg / L concentration of bisphenol A methanol solution, and water bath oscillation was carried out at 25°C, and the adsorption was completed after 4 h; the concentration of bisphenol A was determined by high performance liquid chromatography, and the adsorption capacity was calculated according to the experimental results. The experimental results showed that the adsorption capacity of the bisphenol A molecularly imprinted blended membrane prepared in this embodiment for bisphenol A was 19.5 mg / g.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing a non-molecularly imprinted blended membrane, the steps of which are basically the same as those of Example 3, except that no template molecule bisphenol A is added during the preparation process, and the specific steps are as follows:

[0076] 0.226 g of N-isopropyl acrylamide (NIPAM) was placed in 30 mL of acetonitrile solvent and uniformly dispersed by ultrasonic, and after stirring at room temperature for 10 h, a pre-assembly system was obtained;

[0077] 44 mL of anhydrous ethanol, 13.2 mL of deionized water and 4.4 mL of tetraethyl orthosilicate were added to a flask and mixed uniformly, and ammonium chloride was appropriately added to adjust the pH value of the solution to 3.0; after reaction at a temperature of 60°C for 1 h, ammonia water (mass concentration of 25%) was added dropwise to adjust the pH value to 8 to form a gel, and the gel was calcined at 200°C for 2 h to obtain nano-silicon dioxide powder;

[0078] 6 g of PVDF powder was dispersed in 25 mL of N,N-dimethylformamide (DMF) by ultrasonic for 20 min, 0.2 g of the nano-silica powder was added to obtain a casting solution; the casting solution was sealed and mechanically stirred at 60°C for 12 h, and then left to stand for defoaming. After defoaming, the casting solution was coated on a glass plate by a doctor blade coater (the speed of the doctor blade coater was set to 1.8 m / min, and the thickness of the film was 0.15 mm). Then, the glass plate with the casting solution was subjected to a phase inversion process in water, and the obtained film was separated from the glass plate after solidification and dried at room temperature to obtain a SiO2 / PVDF blend film.

[0079] To the pre-assembled system, 1.88 mL of a mixture of ethylene glycol dimethacrylate and 4 mL of acetonitrile was added to obtain a mixed solution; the SiO2 / PVDF blend film was immersed in the mixed solution, and the oil bath was heated to 50°C for pre-polymerization for 1 h. Then, 0.02 g of azobisisobutyronitrile was slowly added to the mixed solution and ultrasonically dispersed uniformly. After purging nitrogen for 20 min and exhausting oxygen, the polymerization reaction was carried out at 60°C for 24 h under sealed conditions. After the reaction was completed, the film was washed with ethanol and water in sequence to remove un-polymerized functional monomers and cross-linking agents to obtain a non-molecularly imprinted blend film.

[0080] The non-molecularly imprinted blend film was subjected to an adsorption experiment: one piece of the non-molecularly imprinted blend film was placed in a bisphenol A methanol solution with a concentration of 50 mg / L, and the water bath was shaken at 25°C. After 4 h, the adsorption was completed, the concentration of bisphenol A was determined by high performance liquid chromatography, and the adsorption capacity was calculated according to the experimental results. The experimental results showed that the adsorption capacity of the non-molecularly imprinted blend film prepared in the pair of examples for bisphenol A was 9.2 mg / g.

[0081] Tetrabromobisphenol A (TBBPA), p-tert-butylphenol (BP) and 4,4'-dihydroxydiphenyl (DDBP) were selected as competitive adsorbates of bisphenol A (BPA), and the four substances were dissolved in methanol. The concentration of each substrate was 20 mg / L, and the same amount (0.02 g) of film material (bisphenol A molecularly imprinted blend film prepared in Example 3 or non-molecularly imprinted blend film prepared in Comparative Example 1) was weighed into the substrate solution (20 mL). The water bath was shaken at 25°C. After 4 h, the adsorption was completed, the concentrations of the four substrates were determined by high performance liquid chromatography, and the adsorption capacities were calculated according to the experimental results. The results are shown in Table 1. Figure 4

[0082] Figure 4 ​The selective adsorption column chart of the bisphenol A molecularly imprinted blend membrane prepared in Example 3 and the non-molecularly imprinted blend membrane prepared in Comparative Example 1. It can be clearly seen from the chart that the bisphenol A molecularly imprinted blend membrane prepared in the application has a significantly higher adsorption capacity for bisphenol A than any other control substrate in the same concentration of target solution, which indicates that the bisphenol A molecularly imprinted blend membrane prepared in the application has a specific adsorption capacity for the template molecule bisphenol A. At the same time, the bisphenol A molecularly imprinted blend membrane has a higher adsorption capacity for any one of the four substrates than the non-molecularly imprinted blend membrane; while for the non-molecularly imprinted blend membrane, although the adsorption capacities of different substrates are different, the difference between them is small, and the non-molecularly imprinted blend membrane does not have specific adsorption cavities.

[0083] In bisphenol A methanol solutions with different concentrations (5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L), the same amount of membrane material (bisphenol A molecularly imprinted blend membrane prepared in Example 3 or non-molecularly imprinted blend membrane prepared in Comparative Example 1) was placed in a water bath oscillator at 25°C, and the adsorption was completed after 4 h. The concentration of bisphenol A was determined by high performance liquid chromatography, and the adsorption capacity was calculated according to the experimental results, as shown in Table 1. Figure 5

[0084] Figure 5 The static adsorption curve chart of the bisphenol A molecularly imprinted blend membrane prepared in Example 3 and the non-molecularly imprinted blend membrane prepared in Comparative Example 1. It can be seen from the chart that as the concentration of bisphenol A increases, the adsorption capacity of bisphenol A shows an upward trend, and when the concentration of bisphenol A reaches about 30 mg / L, this trend gradually slows down, and when the concentration is 50 mg / L, the adsorption capacity reaches 19.5 mg / g. At any concentration, the bisphenol A molecularly imprinted blend membrane shows a stronger adsorption capacity than the non-molecularly imprinted blend membrane, because the non-molecularly imprinted blend membrane does not have characteristic imprint sites compared to the molecularly imprinted blend membrane, so its adsorption performance is poorer. When the concentration is 50 mg / L, the adsorption capacity of the non-molecularly imprinted blend membrane is 9.2 mg / g.

[0085] Comparative Example 2

[0086] This comparative example provides a preparation method of a silica molecularly imprinted polymer without PVDF membrane, and the specific steps are as follows:

[0087] 0.228 g of bisphenol A (BPA) was placed in 30 mL of acetonitrile solvent and ultrasonically dispersed uniformly. 0.226 g of N-isopropyl acrylamide (NIPAM) was added to the solution, and the pre-assembly system was obtained after stirring at room temperature for 10 h;

[0088] ​Mix 44 mL of anhydrous ethanol, 13.2 mL of deionized water and 4.4 mL of tetraethyl orthosilicate in a flask, and add ammonium chloride to adjust the pH value of the solution to 3.0. After reaction at 60°C for 1 h, add ammonia water (25% by mass) dropwise to adjust the pH value to 8 to form a gel, and then calcine at 200°C for 2 h to obtain a nano-silicon dioxide powder;

[0089] Add 1.88 mL of a mixture of ethylene glycol dimethacrylate and 4 mL of acetonitrile to the pre-assembled system, and then add 0.2 g of the nano-silicon dioxide powder. Pre-polymerize at 50°C for 1 h in an oil bath. Then, slowly add 0.02 g of azobisisobutyronitrile to the mixture, and ultrasonically disperse the mixture. After purging with nitrogen for 20 min to remove oxygen, polymerize at 60°C for 24 h under a sealed condition. After the reaction is completed, centrifuge, and then wash the precipitate with ethanol and water to remove un-polymerized functional monomers and cross-linking agents.

[0090] Wash the polymer prepared in the above step from the template molecules with a mixed solution of methanol and acetic acid, wherein the volume ratio of methanol to acetic acid is 9:1, until no bisphenol A is present in the eluate. Then, wash the obtained membrane with methanol until the washing liquid is neutral. Dry the membrane at 40°C under vacuum for 12 h to obtain a silicon dioxide molecularly imprinted polymer.

[0091] Perform an adsorption experiment on the silicon dioxide molecularly imprinted polymer prepared in the above step: place the silicon dioxide molecularly imprinted polymer of the same mass as that in Example 3 in a bisphenol A methanol solution with a concentration of 50 mg / L, and perform water bath oscillation at 25°C. After 4 h, the adsorption is completed. The concentration of bisphenol A is determined by high performance liquid chromatography, and the adsorption capacity is calculated according to the experimental results. The experimental results show that the adsorption capacity of the silicon dioxide molecularly imprinted polymer prepared in the above step for bisphenol A is 12.1 mg / g.

[0092] As can be seen from the comparison of the adsorption capacities of bisphenol A in Examples 1 to 3 and Comparative Examples 1 to 2, the adsorption performance of bisphenol A in Examples 1 to 3 is better than that in Comparative Examples 1 to 2. Compared with Comparative Example 1, the bisphenol A molecularly imprinted blend membrane has a stronger adsorption capacity than the non-molecularly imprinted blend membrane, because the non-molecularly imprinted blend membrane does not have characteristic imprinting sites, and thus has a poorer adsorption performance. Compared with Comparative Example 2, the adsorption performance of the silicon dioxide molecularly imprinted polymer is better than that of the non-molecularly imprinted blend membrane in Comparative Example 1, but is not as good as that of the bisphenol A molecularly imprinted blend membrane in Examples 1 to 3. Therefore, the bisphenol A molecularly imprinted blend membrane provided in the present application has good adsorption performance and selective recognition ability for bisphenol A.

[0093] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing a bisphenol A molecularly imprinted blend membrane, comprising the following steps: mixing bisphenol A, a first organic solvent and a functional monomer to obtain a pre-assembly system by pre-assembly, wherein the functional monomer is N-isopropyl acrylamide; mixing the pre-assembly system, a crosslinking agent and a second organic solvent to obtain a mixed solution; mixing nano-silica powder, polyvinylidene fluoride and a third organic solvent to obtain a casting solution, and performing film formation on the casting solution to obtain a SiO2 / PVDF blend membrane; placing the SiO2 / PVDF blend membrane in the mixed solution, and performing pre-polymerization and polymerization under the action of an initiator, and then taking out the membrane to elute bisphenol A, thereby obtaining a bisphenol A molecularly imprinted blend membrane. The mass ratio of the bisphenol A and the functional monomer is 0.97:0.9-1.

0. The mass ratio of the nano-silica powder and the polyvinylidene fluoride is 1:20-40. The film formation is performed by phase inversion method. The pre-polymerization is performed at a temperature of 30-60℃ for 0.5-2h.

2. The production method according to claim 1, characterized by, The polymerization is performed at a temperature of 40-80℃ for 24-48h.

3. The preparation method according to claim 1, characterized in that, The first organic solvent and the second organic solvent independently comprise methanol, acetonitrile, ethanol or toluene; and the third organic solvent comprises N-methyl pyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide.

4. The method of claim 1, wherein, 8.A bisphenol A molecularly imprinted blend membrane prepared by the method of any one of claims 1-7, comprising a SiO2 / PVDF blend membrane and a molecularly imprinted polymer loaded on the surface of the SiO2 / PVDF blend membrane.

5. The preparation method according to claim 1, characterized in that, 9.Use of the bisphenol A molecularly imprinted blend membrane of claim 8 in specific adsorption or separation of bisphenol A.

6. The method of claim 1, wherein, ​ 7. The preparation method according to claim 1, characterized in that, ​ ​ ​

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