Preparation Of Molecularly Imprinted Composite Membranes Based On Porous Filler For Separation Of Acteoside

Acteoside（ACT）is the main active component of phenylethanol glycoside（Ph Gs）.It has the effects of protecting liver,anti-aging and enhancing memory.It is widely used in the fields of biomedicine,health care and food fields.At present,it was still challenging to develop a method that can efficiently separate ACT from Ph Gs.Molecularly imprinted membranes（MIMs）can selectively recognize and separate template molecules from complex systems.Therefore,this thesis doped different porous fillers with membrane matrix to design and prepare a series of molecularly imprinted composite membranes with different imprinted structures for the separation of ACT in Ph Gs,and further enhanced the efficient separation of ACT by the membrane through the regulation of imprinted sites,imprinted cavities and affinity sites.The main results are as follows:（1）Design and preparation of molecularly imprinted composite membrane（A-MIHMs）based on Mc M-41:using ACT as template molecule,the composite filler（SMIP-PEI/MCM-41）was prepared by synthesizing ACT based imprinted layer on PEI modified MCM-41 surface and doped it into PVDF matrix to prepare A-MIHMs for selective separation of ACT in Ph Gs.The results showed that A-MIHMs showed excellent selective separation performance for ACT,with adsorption capacity of 96.24 mg·g^-1,adsorption selectivity of 4.48,and permselectivity of 6.37.This was mainly attributed to the construction of"fishing net"imprinted structure in the membrane:on one hand,an interconnected"fishing net"imprinted structure was formed in the membrane to selectively rebind ACT and improve the adsorption performance of ACT.On the other hand,the amino group on PEI surface had a high affinity for the hydrophilic molecule ACT,which improved the adsorption capacity of ACT.Isothermal adsorption and kinetic adsorption showed that the adsorption process of A-MIHMs for ACT was monolayer adsorption,and the adsorption process accorded with pseudo second-order kinetics.The permeation selectivity experiment showed that the separation process of ACT by A-MIHMs accorded with the delayed permeation mechanism.（2）Design and preparation of molecularly imprinted composite membranes（EMINMs）based on multi-pore yolk shell carbon nanospheres（A-HPS@PPy）:the synthesized A-HPS@PPy was doped into PVDF matrix,and ACT imprinted layer was synthesized by sol-gel method on A-HPS@PPy@PVDF membrane surface to prepare EMINMs with multistage imprinted structure for selective separation of ACT in Ph Gs.The results showed that EMINMs showed excellent selective separation performance for ACT,with adsorption capacity of 114.94 mg·g^-1,adsorption selectivity of 4.35 and osmosis selectivity of 7.16.This was mainly attributed to the construction of multistage imprinting structure in the membrane:on one hand,the multistage imprinting structure can selectively recognize and combine the ACT through and improve the selectivity of ACT.On the other hand,the multistage pore structure can screen the free ACT in the membrane and improve the adsorption capacity of ACT.The permeation selectivity experiment revealed that the permeation process of EMINMs to ACT followed the delayed permeation mechanism.（3）Design and preparation of molecularly imprinted composite membranes（DIMICMs）based on ordered mesoporous carbon（CMK-3）:the first ACT-based imprinted layer was synthesized on the surface of DA and KH570 modified CMK-3 to obtain a composite filler（ACT-KH570/PDA/CMK-3）,which was doped into PVDF matrix.The DIMICMs were prepared by synthesizing the second sol-gel imprinted layer on the surface of ACT-KH570/PDA/CMK-3@PVDF to selectively separate ACT from Ph Gs.The results showed that DIMICMs showed excellent selective separation performance for ACT,with adsorption capacity of 105.58 mg·g^-1,adsorption selectivity of 4.64,and osmosis selectivity of 14.61.This was mainly attributed to the construction of a double-imprinted structure in the membrane:on one hand,the double imprinted network structure can fully selectively rebind free ACT,and can double recognize and rebind ACT molecules in the permeation process,greatly improved the selectivity of ACT.On the other hand,CMK-3 has a large specific surface area to adsorb ACT,and the hydroxyl and amino groups on its surface can be used as affinity sites to further improve the adsorption capacity for ACT.The permeation selectivity experiment showed that the separation process of DIMICMs for ACT and ECH accorded with the delayed permeation mechanism.