Preparation And Properties Optimization Of Organic Solvent Nanofiltration Membrane Based On Functional MXene

Organic solvent nanofiltration?OSN?is an emerging technology for membrane separation which separates nanoparticles or macromolecular in the range of 200-1000Da from organic solvent driven by a pressure gradient.It has triggered tremendous attentions owing to the combination of green,efficience,and easy operation.Organic solvent nanofiltration membrane is the core of OSN process which directly affects the performance of OSN process.At present,preparing OSN membranes with favorable nanofiltration performance is urgently required to accommodate complex solvent systems.According to coupling hybridization and cross-linking technology,this paper combined the respective advantages of organic and inorganic materials and prepared the OSN membranes with favorable nanofiltration performance by embedding functionalized two-dimensional nanosheets into polymer matrix to construct effective pathway for the solvent molecules.Functionalized Ti₃C₂T_x nanosheets with different groups were facilely synthesized by respectively grafting organofunctional siloxanes,so as to regulate the affinity of OSN membrane towards different solvent molecules.Hydrophilic polyethyleneimine?PEI?and hydrophobic polydimethylsiloxane?PDMS?were selected as two types of polymer matrixes to prepare OSN membranes.Cyclodextrins?CDs?with hydrophilic shell and hydrophobic cavity were grafted onto the surface of Ti₃C₂T_x nanosheets to construct effective pathway for both polar and non-polar solvent molecules and enhance the nanofiltration performance of OSN membranes.The detailed research works were summarized as follows:?1?The preparation of OSN membranes by embedding functionalized Ti₃C₂T_x nanosheets with different groups.Ti₃C₂T_x nanosheets as a newly-discovered family of2D metallic carbide/carbonitrides materials had great potentials in fabricating functional polymer composites.The abundant surface groups on Ti₃C₂T_x nanosheets allowed facile modification,and thus four functional groups were grafted on Ti₃C₂T_x surface respectively,which was found to strongly affect the affinity towards solvent molecules and further determine the nanofiltration performance of membranes.Interestingly,the functional groups on Ti₃C₂T_x,namely-NH₂,-COOR,-C₆H₆,and-C₁₂H₂₆,could effectively enhance the flux for isopropanol,ethyl acetate,toluene,and n-heptane,respectively,no matter the polymer matrix was hydrophilic PEI or hydrophobic PDMS.?2?The preparation of OSN membranes by embedding Ti₃C₂T_x nanosheets grafted with CDs.CDs had attracted considerable attentions due to their hydrophilic shell and hydrophobic cavity which endow CDs with prominent performance in specific applications.Novel OSN membranes were fabricated by incorporating functionalized Ti₃C₂T_x nanosheets which were obtained by grafting CDs onto Ti₃C₂T_x in hydrophilic PEI.The CDs on Ti₃C₂T_x were found to significantly affect the affinity towards non-polar solvent molecules,and thus enhance the flux.In this sense,hydrophilic PEI worked as carrier sites for polar solvent molecules and CDs for non-polar.Under the pressures of 10 bar,the flux of PAN/PEI-Ti₃C₂T_x-?-CD for isopropanol,n-heptane,and toluene were 40.5,37.2,and 30.6 L m^-2 h^-1,respectively.