Controllable Preparation Of MXene-based Multilayer Artemisinin Imprinted Composite Membranes And Research On Enhanced Selective Separation Performance

Artemisinin was the most widely used drug molecule in the anti-malarial field worldwide and was considered by the World Health Organization to be the most effective antimalarial drug.Considering the wide range of antiviral effects and pharmacological activities of artemisinin,and the traditional separation method is complicated,energy-consuming not environmentally friendly,it is crucial to investigate and develop a selective separation method for the effective isolation and extraction of artemisinin.Molecularly imprinted membranes（MIMs）was a highly selective separation technology based on the coupling of two superior technologies:molecularly imprinted technology（MIT）and membrane separation technology（MST）.In recent years,MIMs has shown unique advantages in the fields of selective separation,extraction,enrichment and purification.However,conventional MIMs still suffer from bottlenecks such as low adsorption performance,poor selectivity and low permeate flux.Therefore,it was important to develop MIMs with high selectivity and high permeability to achieve selective separation and extraction of artemisinin from complex composition systems.In this context,this thesis utilizes surface imprinting technology to construct MXene-based multilayer imprinted composite membranes with high inhalation capacity,selectivity and permeation flux by introducing a functional two-dimensional material（Ti₃C₂T_xMXene）as a template molecule and modulating and optimizing its binding mode with the substrate membrane to achieve selective separation/extraction of artemisinin in a mixed system.In this paper,the specific recognition mechanism of MIMs imprinted sites and the interaction between imprinted sites and artemisinin molecules were investigated in depth,which provided research ideas for the study and development of ideal artemisinin molecular imprinted membranes.The main studies are as follows:1.Construction of framework-like multilayer MIMs based on MXene-Si O₂synergistic functionalization concept and study on selective separation of artemisininIn order to enhance the adsorption capacity and selectivity,MIMs were prepared by blending with MXene nanosheets and mesoporous Si O₂nanoparticles,followed by base etching of pdda wrapped on the surface of mesoporous Si O₂nanoparticles to form a flexible backbone to improve the permeation flux and hydrophilicity of the material,and grafting of imprinted sites on the membrane surface and within the pore channels using thiol-ene click chemistry with artemisinin as the target molecule,MXene-Si O₂framework functionalized membranes（CSMPMs）with multiple imprinted sites were prepared.In addition,the properties of the prepared CSMPMs were characterized by isothermal adsorption,kinetic adsorption,selective adsorption,selective permeation and dynamic permeation selectivity experiments.The results showed that the CSMPMs obtained excellent selective separation factors(α_{Artemisinin/Artesunate}=3.18,αArtemisinin/Dihydroartemisinin=2.58),as well as good permeation selectivity(βDihydroartemisinin/Artemisinin=3.17,β_{Artesunate/Artemisinin}=2.89).The adsorption state of CSMPMs on artemisinin was measured using ATR-FTIR,and the adsorption mechanism of CSMPMs was investigated in depth.The dynamic permeation results showed that the CSMPMs had excellent stability(γ_{Artemisinin/Artesunate}=3.23,γ_{Artemisinin/Dihydroartemisinin}=2.87)and also exhibited stable regeneration performance.2.Preparation of high-density site MIMs based on in situ Ui O-66 modified MXene composite layer and study on performance and mechanism of selective separation of artemisininUi O-66@MXene blended composite membranes（UMPMs）were prepared by thiol-ene click chemical imprinting using in situ growth method by loading Ui O-66 nanoparticles on MXene nanosheets,which not only inhibited MXene restacking but also provided high porosity and specific surface area,in order to construct high porosity and effective imprinting sites.The results showed that the constructed UMPMs exhibited good adsorption selectivity(α_{Artemisinin/Artesunate}=5.63 andα_{Artemisinin/Dihydroartemisinin}=4.64)and excellent permeation selectivity(β_{Artesunate/Artemisinin}=4.54 andβ_{Dihydroartemisinin/Artemisinin}=4.09),attributed to the effective selective recognition of the imprinted sites.In addition,the regeneration cycle experiments and dynamic infiltration experiment of UMPMs verify the excellent stability of UMPMs,and further emphasize the significance and potential of UMPMs in practical application.3.Construction of two-dimensional GO/MXene self-supporting laminar imprinted composite membrane based on self-supporting technology and study on performance and mechanism of selective separation of artemisininIn order to solve the problem that some of the imprinted sites were embedded inside the membrane due to the blending method,resulting in low utilization of the imprinted sites,a two-dimensional GO/MXene self-supporting laminar imprinted composite membrane（CGMMs）was designed and prepared,and the use of organic solvents in the phase inversion method,which was not meet the requirements of green chemistry development.Firstly,PDA was used to modify MXene to form a PDA hybrid coating on the MXene surface,which could effectively improve the oxidative embrittlement and hydrophilicity of MXene.Subsequently,the effects of different additions of GO on the surface morphological structure and wettability of self-supported lamellar membranes were investigated by dispersion filtration of GO and MXene nanosheets in specific ratios,and MXene-based spherically imprinted polymers were successfully constructed on the surface of stacked GO/MXene nanosheets as well as between the layers by thiol-ene click chemical imprinting.The performance of CGMMs was explored by isothermal adsorption,kinetic adsorption,selective adsorption tests and selective permeation tests.The equilibrium adsorption capacity of CGMMs reached 36.10 mg g^-1with satisfactory selective separation capacity(α_{Artemisinin/Artesunate}=4.10 andα_{Artemisinin/Dihydroartemisinin}=3.03)and excellent permeation selectivity(β_{Artesunate/Artemisinin}=5.7 andβ_{Dihydroartemisinin/Artemisinin}=4.4),which implied the successful construction of effective artemisinin-imprinted sites on CGMMs.The key to the excellent rebinding ability and selectivity exhibited by the prepared CGMMs is that the cross-section of CGMMs is composed of MXene nanosheets and GO nanosheets superimposed on a laminar structure dotted with imprinted polymers,which extends the molecular transport channels and facilitates the construction of more molecular imprinting sites.