Mixed matrix blend membranes of poly(vinyl alcohol)–poly(vinyl pyrrolidone) loaded with phosphomolybdic acid used in pervaporation dehydration of ethanol

Mixed matrix blend membranes of poly(vinyl alcohol)–poly(vinyl pyrrolidone) (PVA–PVP) loaded with 4, 8 and 12 wt.% of phosphomolybdic acid (PMA) were prepared and characterized by FTIR, XRD, SEM, DSC, dynamic mechanical testing analysis (DMTA) and contact angle measurements. The extent of PMA loaded in the membrane affected the PV performance during ethanol dehydration. Selectivity calculated from permeability ratio of two components of a membrane was higher for 4 wt.% PMA-loaded membrane than those of 8 and 12 wt.% loaded membranes. At the azeotropic mixture composition of 4% of water and remaining ethanol, the 4 wt.% PMA-loaded membrane gave a selectivity of 8206 and a flux of 3.75 g/m2 h kPa. Accordingly, this membrane was further investigated in detail to understand the effect of variations in feed water composition and temperature on its PV performance. Sorption and diffusion results in conjunction with PV data were analyzed in terms of modified Flory–Huggins theory for three-component system. Heat of sorption, calculated from Arrhenius relationship was negative, suggesting Langmuir mode of sorption.