초록
Bioethanol is a renewable biofuel that has a strong inhibitory effect on cells in bioethanol fermentation by yeast. In this study, carbon nanotube (CNT)-mixed polydimethylsiloxane (PDMS) membranes were used for ethanol recovery from model solutions as well as for fermentation by self-flocculating yeast. Imbedding CNTs into the PDMS membrane led to enhanced ethanol recovery, with a maximum total flux of 128.7g/m<SUP>2</SUP>h and an ethanol titer of 615.1g/L in permeate. The CNTs can provide a flexible route for ethanol transport through the inner tubes or along the smooth surface. In fed-batch fermentation incorporating pervaporation, 112.3g/L of ethanol was produced with an overall ethanol productivity and yield of 2.23g/Lh and 0.45g/g, respectively. The membrane produced a highly concentrated condensate containing 400.3-487.5g/L of ethanol. Furthermore, as yeast flocs can be throttled down in the bioreactor, self-flocculating yeast can be used to prevent membrane fouling induced by cell adsorption on the membrane. Therefore, the CNT-mixed membrane coupled with ethanol fermentation by self-flocculating yeast not only reduces ethanol-mediated inhibition of cells but also saves the production cost because of the reduced fouling risk. Thus, this combination approach has potential in industrial bioethanol production for long-time operation.