Pervaporation Performance of Ag-PVA Nanocomposite Membranes: Effect of Operating Temperature

Abstract

The features of pervaporation are continuously improved with the production of more and more efficient membranes. In our present study, silver nanoparticles are in-situ generated in a poly (vinyl alcohol) using solution-casting in order to enhance its capability for pervaporation. The membrane is tested on the case study of ethanol dehydration by pervaporation. Effect of silver content on the pervaporation separation index and the enrichment factor of the membrane at 15 % mass water at 40 °C are reported. Pervaporation data for nanocomposite membranes show around 100 % increase in the water permeance values while the intrinsic selectivity decreases that is typical for pervaporation membranes. The water permeances of original crosslinked PVA membrane and the 2.5 % silver loaded PVA membrane are 26.65 and 70.45 (g/m².kPa.h), respectively. The values of total flux are closely related to water flux, showing that membranes could be successfully assigned to separate water from ethanol even at the azeotropic point. The influence of temperature on the efficiency of the pervaporation process, permeation parameter and diffusion coefficient of the feed component is also discussed. The negative heat of sorption (∆Hs) values calculated on the basis of the estimated Arrhenius activation energy values indicates that the sorption process is controlled by Langmuir's mode. Our results show that the 0.5 mass% silver loaded poly (vinyl alcohol) membrane exhibits excellent PV performance.