Construction Of PVDF Based On Molecularly Imprinted Composite Membrane And The Selective Separation Performance And Mechanism Of Enoxacin

Enoxacin exists in the wastewater environment with bioaccumulation,ecotoxicity and low residual content characteristics,which poses a potential threat to the ecological environment and human health.Therefore,to establish a fast,simple,low energy consumption and high selectivity separation technology of enoxacin has a great research value.Molecular imprinting technique?MIT?is a method for selective separation of targets from complex systems.And it is widely used in chemical separation processes by forming selective recognition sites at synthesizing polymers process.Molecularly imprinted membranes?MIMs?have attracted a great deal of attentions,which combine the advantages of MIT and membrane separation technique?MST?with low enegy consumption,easy operation,easy recovery,good permeability and high selectivity to selectively separate and adsorpt molecules.However,the service life of MIMs is influenced by the limitation of low permeable flux,poor cycling usability and low stability.Therefore,improving the multiple properties of membrane materials to obtain diversity requirements has become one of the breakthrough points for sustainable development of MIMs.In this paper,enoxacin imprinted nanocomposite membrane was successfully prepared by combining MIT,MST,biomimetic dopamine self-polymerization composite modification technology and nanocomposite modification technology,successfully prepared MIMs by different methods and analytical methods with enoxacin as targets for selective separation and adsorption enocaxin.As-prepared membranes not only retained the advantages of high selectivety fo traditional MIMs,but also improved the hydrophilicity,stability,stain resistance and regenerability to prepare the ideal functional enoxacin imprinted composite membranes.The details are as follows:1.Preparation of PVDF based molecularly imprinted composite membranes locaded on carbon nanotubes for selectively separation enoxacinThe highly selective PVDF based molecularly imprinted composite membranes locaded on carbon nanotubes?EINCMs?were prepared by polydopamine?pDA?bioadhesive technology,free radical polymerization technique and sol-gel blotting polymerization technique based on multi-walled carbon nanotubes?CNTs?as carrier with enoxacin as template molecule.The EINCMs was used for selective adsorption and separation of enoxacin molecules.The synthesized products were characterized by characterization tests,and the adsorption and permeation experiments were carried out to study the selective separation of enoxacin by EINCMs.To compare with the adsorption capacity results of EINCMs was reached 31.56 mg g^-1,and the imprinting factor was about 4.44,which palyed a great role in selective adsorption and separation enoxacin in the wastewater.2.Preparation of cyclodextrin-induced PVDF based molecularly imprinted composite membranes for selectively separation enoxacinBased on chemical grafting and surface imprinted polymerization methods,the cyclodextrin-induced PVDF based molecularly imprinted composite membranes?EIPCMs?were prepared by grafting cyclic oligosaccharide molecular cyclodextrin on the membrane surface with enoxacin as the target.The method of surface imprinted polymerization formed imprinting sites on the membrane surface,effectively reduced the embedding of the imprinting sites to improve the utilization rate of the imprinting sites.The surface morphology and chemical composition were systematically characterized by various characterizations.And according to adsorption and permeation tests,the results showed that the adsorption capacity of EIPCMs was more than three times of non-imprinted membrane?NIPCMs?.At the same time,the imprinting factor?was reached 3.15,and the selective permeation factor?was reached 5.16,which promoted the efficiency of imprinting and selective separation performance for enoxacin.3.Preparation of carbon nanospheres modified PVDF based molecularly imprinted composite membranes for selectively separation enoxacinThe carbon nanospheres modified PVDF based molecularly imprinted composite membranes?CBMIMs?were developed by one-pot economical approach for in-situ modification of carbon nanospheres sol?CNS?during phase inversion process for increasingly antifouling property.Using pDA as hydrophilic coating layer and second reaction platform,made the imprinting polymer layer hydrophilic to avoid the adsorption of contaminant protein.The structure morphology and surface bonding mode were characterized by SEM,TEM and XPS.The combined performance tests presented that the equilibrium adsorption capacity and imprinting factor of CBMIMs reached 32.26 mg g^-11 and 3.15,respectively.As-prepared CBMIMs not only had high hydrophilicity and anti-fouling property,but also exhibited excellent selective recognition and separation effects on enoxacin molecules,which promoted the separation application.4.Preparation of organic-inorganic hybrid nanoparticles modified PVDF based molecularly imprinted composite membranes selectively separation enoxacinThe inorganic silica?SiO₂?nanoparticles with hydrophilicity and mechanical stability were grafted with high hydrophilicity and high biocompatibility of low molecular weight organic molecules,which effectively improved the incompatibility of the inorganic nanoparticles with the polymer structure.Subsequently,the surface imprinting polymerization process was carried out for the preparation of the organic-inorganic hybrid nanoparticles modified PVDF based molecularly imprinted composite membranes?SPEIMs?by freezing method.According to various characterizations,SPEIMs formed a special tubular porous structure,greatly increasing the specific surface area and fulx.At the same time,the equilibrium adsorption capacity of SPEIMs was 55.96 mg g^-1,which was about five times than that of non-imprinted membranes?SPNIMs?,and after six cycle's adsorption researches,the regeneration performance was still 90.31%of initial adsorption amount.The selective separation of enoxacin molecules has broad application prospects.