Separation of ethanol from ethanol-water mixture and fermented sweet sorghum juice using pervaporation membrane reactor

摘要

Ethanol is an important renewable energy that can be produced from byproducts of agricultural products such as cassava, corn, potato, sorghum and sugar cane etc. via chemical and bio-fermentation processes. Pervaporation, an effective and economical membrane technology, has been proven to substitute distillation process for ethanol separation. In this work, the separation of two types of mixtures; ethanol-water mixture and fermented sweet sorghum were investigated using cellulose acetate membranes. The pervaporation performances of the two mixtures were carried out under various operating conditions such as ethanol concentrations (10%, 15%, 20% and 30%), operating times (15, 30, 45 and 60 min) and temperatures (50 °C, 60 °C and 70 °C). The permeate fluxes, selectivity and percent separation declined significantly under all operating conditions in the presence of sweet sorghum fermentation broth when compared to the binary mixture. Preliminary economic analysis shows that cost of producing 1 l of ethanol from the broth is about 1.0 $/l which is about 1.2 times higher than from the pure binary system and approximately 5 times higher than the minimum production cost of 0.2$/l reported by Wasewar and Pangarkar (2006) [20].