Endocrine disruptors(EDCs)are a new class of chemical pollutants that can interfere with the normal physiological function of biological endocrine system.They will accumulate in large quantities in the environment and pose a continuous threat to the ecosystem and human health.As a conventional technology for removing endocrine disruptors from water,physical adsorption technology has the advantages of simplicity,high efficiency and low cost.However,in the actual application process,the adsorbent is often faced with the key defects of difficult recycling and poor specific adsorption performance.Molecular imprinting modification of the adsorbent can make it have specific adsorption properties,and the modified adsorbent can be reused by loading the surface of the separation membrane.Therefore,in this study,molecular imprinting technology was combined with membrane separation technology to successfully prepare molecular imprinting polymers(MIPs)and molecular imprinting membranes(MIMs)with specific selective removal properties for the typical endocrine disruptor-tetrabromobisphenol A(TBBPA),providing material options for the construction of a technical scheme to reduce the typical endocrine disruptors in water.Specific research contents and results are as follows:(1)The prepared molecularly imprinted polymers(MIPs),which using TBBPA as the template molecule,4-vinylpyridine(4-VP)as the functional monomer,ethylene glycol dimethacrylate(EGDMA)and azodiisobutyronitrile(AIBN)as the crosslinking agent and initiator,was loaded on the modified nano silica surface by surface imprinting method.By optimizing the molar ratio between different raw materials,the optimal molar ratio of template molecule,functional monomer and crosslinking agent(1:4:20)was obtained.The selective adsorption experiments were carried out under optimal conditions,which proved the specific adsorption capacity of the MIPs for TBBPA.The molecularly imprinted layer was successfully grafted to the surface of nano-Si O2 by Transmission Electron Microscope(TEM),Fourier Transform Infrared Spectrometer(FTIR)and X-ray Photoelectron Spectroscopy(XPS)characterization.(2)To solve the recycling problem of molecularly imprinted polymer,A preparation method combining molecular imprinting technology and membrane separation technology was proposed in this study,so as to achieve the selective recognition and separation of TBBPA in water.The experimental results showed that the optimal loading load of MIPs on the membrane was 5 mg,and it was obvious that it was loaded on polyvinylidene fluoride(PVDF)membrane under scanning electron microscope.The average roughness(Ra)of MIMs was 110 nm higher than that of the original PVDF membrane under atomic force microscope,which proved that MIPs was successfully loaded on the membrane.Molecular imprinted membranes have high adsorption capacity and selective separation performance.Langmuir model can well describe the adsorption of molecular imprinted composite membranes on TBBPA.In conclusion,the prepared molecularly imprinted membrane of TBBPA is a homogeneous monolayer adsorption process.The pseudo-two-stage model fits better than the first-stage model,which indicates that chemisorption plays a leading role in molecularly imprinted composite membranes.The separation factor of molecularly imprinted membranes was up to 6.07,which was much better than that of non-molecularly imprinted membranes(NIMs),which was 1.78.In addition,the regeneration experiment proved that the molecularly imprinted membrane has good repeatability for selective adsorption of target pollutants,and the adsorption amount of MIMs can still reach 90%of the initial result after repeated use.(3)The permeation performance and mechanism of the membrane were studied and it was concluded that the separation mechanism which hindered the permeation played A leading role in the permeation process of TBBPA.The permeability selection coefficients of MIMs for p-bisphenol A(BPA),4,4’-dihydroxybiphenyl(DDBP)and p-tert-butylphenol(BP)were 5.24,6.31 and 6.74,respectively.Since the imprinting site of TBBPA was not constructed in non-molecularly imprinted membranes(NIMs),the penetration factor of NIMs was much lower than that of MIMs,which remained around 1.0.The results showed that the molecularly imprinted composite membrane has the ability to capture template molecules specifically,and has good separation performance and scalability.The simulated water samples were treated with molecularly imprinted composite membranes,which proved that the molecularly imprinted composite membranes had good anti-interference performance in the process of reducing TBBPA in water,and demonstrated that molecularly imprinted composite membranes had broad application prospects in the field of membrane selective recognition and separation. |