Pervaporation separation of water–isopropanol mixtures using silicotungstic acid loaded sulfonatedpoly(ether ether ketone) composite membranes

Composite membranes of sulfonatedpoly(ether ether ketone) (sPEEK) containing nascent and modified silicotungstic acid (STA) nanoparticles were tested for pervaporation (PV) separation of water–isopropanol mixtures. The performance of filler loaded composite membranes was better than that of nascent polymer membranes. The chemically modified STA containing membranes showed improved PV performance compared to those of nascent STA loaded membranes. This effect is attributed to leaching of STA during the PV cycles. The leaching effect was reduced after modification of STA with cesium carbonate. Among all the composite membranes prepared by the solution casting method, the membrane containing 7 wt% modified STA gave the highest PV separation performance compared to those containing 3, 5 and 10 wt% STA. The PV performance of the 7 wt% STA loaded membrane was further tested as a function of feed water composition from 10 to 25 wt% and a temperature range of 30–60 °C. Characterization of the membranes was done by universal testing machine (UTM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The PV results have been explained in terms of sorption–diffusion principles and Arrhenius activation parameters.