Three-component mixed matrix organic/inorganic hybrid membranes for pervaporation separation of ethanol–water mixture

Mixed matrix membranes (MMMs) were made by incorporating vinyltrimethoxysilane (VTMS)-modified Silicalite-1 zeolite nanoparticles (V-Silicalite-1 NPs) into fluorinated polybenzoxazine (F-PBZ) modified polydimethylsiloxane (PDMS) polymer through in situ polymerization method. The membrane morphology, surface wettability, and pervaporation performance were systematically investigated. The addition of F-PBZ into PDMS membranes resulted in substantially improved flux and marginal increase of separation factor, which is the result of higher free volume and higher hydrophobicity caused by the addition of F-PBZ. The modification of Silicalite-1 NPs improved the interfacial contact between zeolite crystals and polymer phase. The incorporation of hydrophobic V-Silicalite-1 zeolite NPs into the PDMS membranes led to much higher separation factor but reduced flux, which is the result of increased hydrophobicity and reduced free volume. The three-component MMMs with V-Silicalite-1 zeolite NPs in the F-PBZ fluorinated PDMS exhibited separation factor of 28.7 and flux of 0.207 kg m⁻² h⁻¹ for 5 wt % ethanol aqueous solution at 50 °C, while the pure PDMS membranes only had separation factor of 4.8 and flux of 0.088 kg m⁻² h⁻¹. The substantial increase of both flux and separation factor were attributed to the higher hydrophobicity and free volume caused by the incorporation of both hydrophobic zeolite crystals and F-PBZ polymer into the PDMS membranes.