Novel adsorbent membranes of poly (vinyl alcohol) and ZSM-5 for pervaporation dehydration of ethanol at their azeotropic point
Mallikarjunagouda B Patil, Amshumali MK
The study reports on the development of hybrid adsorbent membranes of poly(vinyl alcohol) (PVA) loaded with hydrophilic ZSM-5 i.e., zeolite in different compositions from 1 to 10 wt. % that are used for pervaporation (PV) dehydration of ethanol at azeotropic point from aqueous mixtures of 4.1 wt. % water at 30°C. The PV performance of hybrid adsorbent membranes were much superior to that of plain PVA membrane in terms of selectivity and flux due to increased hydrophilicity of PVA membrane in the presence of ZSM-5 zeolite particles that are also hydrophilic. The membranes were crosslinked with tetraethyl ortho silicate (TEOS) and confirmed by Fourier transform infrared spectroscopy (FTIR) and by calculating the ion exchange capacity (IEC). Morphology of the membranes was assessed by scanning electron microscopy (SEM). Sorption studies have been performed to evaluate the extent of interaction and degree of sorption of the membranes. It is observed that flux and selectivity increased with increasing amount of ZSM-5 particles in the PVA matrix. In case of hybrid adsorbent membrane containing 10 wt. % of ZSM-5, selectivity for water was 1320 and a flux of 0.366 kg/cm2 h was attributed to combined effects of molecular adhesion between particle surfaces and PVA matrix. Higher selectivity of the adsorptive membrane was found compared to the plain PVA membrane.