Effects of Ca2+ bridge cross-linking on structure and pervaporation of cellulose/alginate blend membranes

Blend membranes prepared by coagulating the mixture of 8 wt.% cellulose cuo xam and 8 wt.% aqueous sodium alginate solution were cross-linked by using Ca2+ bridge in 5 wt.% CaCl2 aqueous solution. Pervaporation separation para meter of ethanol-warer mixtures through the blend membranes was measured by a pervaporation apparatus. The effects of Ca2+ cross-linking and operating temperature on the permeation flux and separation factor were investigated and discussed. The results from IR, DMA and X-ray diffract ion indicated t hat the strong interaction between cellulose and alginate exists in the ble nd membranes. For the Ca2+ cross-linked blend membranes, which have relativ ely higher density and crystallinity, the permeation flux hardly changed, w hile the pore size measured from the flow rate method decreased. Moreover, the cellulose/alginate (8:2, by weight) blend membrane cross-linked with Ca 2+, showed the higher pervaporation separation factor for 90% alcohol feed mixture at 60 degrees C and the higher the permeation flux at lower tempera ture than that of uncross-linked membrane, owing to Ca2+ bridge. The mechan ical properties of alginate membranes were significantly improved by introd ucing cellulose and Ca2+ bridge. Its tensile strength was 12 times higher t han that of alginate membrane. (C) 2000 Elsevier Science B.V. All rights re served.