Mixed matrix membranes of poly(vinyl alcohol) loaded with phosphomolybdic heteropolyacid for the pervaporation separation of water–isopropanol mixtures

Mixed matrix membranes of poly(vinyl alcohol) (PVA), loaded with phosphomolybdic heteropolyacid (HPA) and crosslinked with glutaraldehyde have been prepared by the solution casting technique. Pervaporation (PV) experiments have been performed at 30 °C to separate water–isopropanol feed mixtures containing 10–40 wt.% of water. The membranes were characterized by differential scanning calorimetry (DSC) and dynamic mechanical thermal analyzer (DMTA) to understand their thermal behavior and mechanical strength properties. At high content (i.e. 7 wt.% with respect to weight of PVA) of HPA, the mixed matrix membranes could extract water efficiently on the permeate side with a selectivity of 90,000 and a flux of 0.032 kg/m2 h for 10 wt.% of water containing feed mixture (the lowest feed composition of water studied). Flux of the mixed matrix membranes decreased with increasing concentrations of HPA; however, a significant improvement in PV performance was observed for HPA-loaded membranes than the pristine PVA. DSC and DMTA analyses indicated a decrease in melting temperature and an increase in glass transition temperature, respectively.