Phosphotungstic acid loaded sodium alginate membranes for enhanced Pervaporative dehydration of Isopropanol

The Plain sodium alginate (NaAlg) and 5 wt % and 10 wt % phosphotungstic acid(PWA) incorporated NaAlg membranes have been fabricated by solution casting followed by solvent evaporation. The membranes formed were crosslinked with glutaraldehyde and tested for PV dehydration of isopropanol from their aqueous feed mixtures at water concentrations (5, 10, 15 and 25 wt %) at 30◦C. The crosslinking reaction was confirmed by Fourier transform infrared (FTIR) measurements. The selectivities of isopropanol - water feed mixtures were 1689 and 2134 with fluxes of 0.2283 and 0.2274 kg/m2 h for 10 wt % water in the feed mixture for filled membranes containing 5 wt % and 10 wt % of (PWA) particles respectively. Flux data also improved considerably for both the feeds. However, the virgin crosslinked NaAlg membrane has selectivity and flux values of 653 and 0.067 kg/m2 h, respectively, for Isopropanol – water, when tested for 10 wt % water containing feed. It is demonstrated that addition of PWA particles as fillers into the NaAlg matrix has improved both flux and selectivity values over that of the crosslinked virgin NaAlg membrane. Such improvements in the selective nature of the filled matrix membranes are attributed to the water absorbing capacity of the PWA particles.