Abstract: The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process. Furfural and benzaldehydewere selected as extraction solvents,withwhich the solubility of water is small, expecting large distribution coefficient of ethanol. The liquid-liquid two-phase region was the largest with m-xylene solvent, followed by benzaldehyde and furfural. The region of two liquid-liquid phase becamelarger with themixed solvent ofm-xylene and furfural than that with furfural solvent. The NRTLmodelwas applied to the ethanol-water-furfural-m-xylene system, and the model could well express the liquid-liquid equilibrium of the system. For any solvent used in this study, the separation selectivity of ethanol relative to water decreased as the distribution coefficient of ethanol increased. The separation selectivity with m-xylene was the largest among the employed solvents, but the distribution coefficientwas the smallest. The solvent mixture of furfural andm-xylene showed relatively high distribution coefficient of ethanol and separation selectivity, even in the higher mass fraction of m-xylene in the solvent phase.
The ethanol extraction with a countercurrent multistage extractor by a continuous operation was simulated to evaluate the extraction performance. The ethanol content could be concentrated in the extract phase with relatively small number of extraction stages but low yield of ethanol was obtained.

Key words: Bioethanol, Solvent extraction, NRTL model