Preparation And Pervaporation Performance Of Polyetherketone/MOFs Nanocomposite Membranes

Pervaporation is an efficient technology for separating liquid mixtures and have been widely applied for the purification of many mixed liquid systems.It has lots of advantages including remarkable purification efficiency,low energy consumption,greenness and environmentally friendly.The membrane materials play an important role in the pervaporation process,which dictate the types of separation system and efficiency.Cardo polyetherketone(PEK-c)as a commercial engineering thermoplastic polymer containing linear aromatics in its molecular chains is a key polymer membrane material for pervaporation.However,low permeability existing in this process limits its practical application in industry.Metal-Organic-Frameworks(MOFs)are new porous materials consisting of metal ion or metal ion cluster in an organic chain.Because of their excellent physical-chemical characteristics,which are suitable to be used as a kind of filler incorporation into polymer materials,we employed them in this work through blending to form composited membrane for improved pervaporation performance.The main results are presented as follows:(Ⅰ)The ZIF-8 nanoparticles with sizes in the range of 20-50 nm were synthesized by hydrothermal method and then incorporated into the PEK-c matrix to produce the PEK-c/ZIF-8 nanocomposite membranes.The PEK-c/ZIF-8 composite membranes were used to evaluate purification separation performance of water and methanol from MTBE.The membranes’ morphology,physicochemical properties and mechanical stability were characterized in detail.Effects of ZIF-8 loading on the membrane structure and pervaporation performances were studied in the range of 0-20 wt%ZIF-8.(Ⅱ)The ZIF-67 nanoparticles with size of 700 nm were also prepared and embedded into PEK-c to form PEK-c/ZIF-67 nanocomposite membranes.The PEK-c/ZIF-67 membranes were used for the dehydration separation performance of water from ethanol.The effect of ZIF-67 filler loading on the membranes’ morphology,physicochemical properties and mechanical stability were examined in detail.In general,it was found that the ZIFs nanoparticles could provide lots of nanoscale pores while the interaction between nanoparticles and polymer chains can produce interfacial gaps,which form many transport channels for the transport of small molecules and prevent large ones from passing through the membranes.The presence of MOFs particles increases the surface roughness of the pristine polymer membrane,improves the hydrophilicity of the nanocomposite membrane and increases the sorption capacity of permeation components,all of which are beneficial to the improvement of the separation performance.The permeation and selectivity of the membranes were enhanced with increasing content of MOFs fillers.But further increase of MOFs loading increases the permeation flux while the selectivity is decreased.The developed series of PEK-c/ZIF-8 and PEK-c/ZIF-67 nanocomposite membranes with good mechanical properties,low swelling degree and high thermostability exhibit high permeability and selectivity for pervaporation.Hence,they present promising good application prospect in separation of impurities from organic solvent and potential industrialization.