Separation of ethanol-water mixtures by pervaporation using sodium alginate/poly(vinyl pyrrolidone) blend membrane crosslinked with phosphoric acid

The blend membranes of sodium alginate (SA) and poly(vinyl pyrrolidone) (PVP) are prepared by physical mixing of SA and PVP. The membranes are crosslinked with phosphoric acid and used in the pervaporation separation of a water + ethanol mixture at 30 degrees C. Fourier transform infrared spectroscopy and ion exchange capacity confirmed the crosslinking reaction. Thermal stability and crystallinity are determined from TGA and XRD studies. The membrane performance is studied by calculating flux, selectivity, and pervaporation separation index. Sorption studies are carried out to evaluate the extent of interaction and degree of swelling of the membranes in pure liquids as well as in binary mixtures. The effect of experimental parameters such as feed composition, membrane thickness, and permeate pressure on separation performance of the crosslinked membranes is determined. The membrane appears to have good potential for breaking the aqueous azeotrope of 96 mass % ethanol with the selectivity of 364 and substantial water flux of 0.5 kg m(-2) h(-1) 10 mu m.