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Abstract

The production of ligno-cellulosic ethanol is gaining wide interest with the progressive depletion of fossil fuels. Pervaporation, which is a selective membrane separation process that consumes relatively low energy, is being proposed for utilization within the ethanol production scheme. This work is dedicated to investigations on the application of pervaporation using simulated solutions in two stages namely, concentration of ethanol during fermentation using hydrophobic polydimethylsiloxane (PDMS) spiral wound membrane and dehydration of high concentration ethanol using hydrophilic optimized silica membrane. A semi-pilot plant based on a novel conceptual process design combining both membranes to be used interchangeably has been developed. The hydrophobic PDMS system has been operated using spiral wound module of area 0.6 m2 at a flow of 600 L/h and vacuum less than 0.1 mbar. Within the tested range of ethanol concentration, the flux (g/m2/h) varied between 780 and 2300 with a max separation factor of 3.67. The tubular hydrophilic membrane of area 0.04 m2 has been operated at a flow of 300 L/m3 and vacuum of less than 0.1 mbar. The flux and concentration have been measured during the experiments at suitable time intervals. At about 95% initial ethanol concentration, the flux ranged between 2700 and 3400 (g/m2/h) and the separation factor reached about 122. For both operational modes, the results reflect optimum conditions for operation with maximum flux and acceptable separation factor. It is concluded that pervaporation proves to be a viable option for separation and dehydration of ethanol due to its technical performance and minimum energy usage.