abstract
Bio-alcohols are produced from biomass by fermentation, and distillation is commonly used to separate the alcohol from the aqueous phase. This is, however, a high energy consumption process, and alternative approaches to this separation are being pursued. In this work, the use of phosphonium-based ionic liquids (ILs) for the extraction of ethanol from fermentation broths is investigated. Ternary phase diagrams, necessary for the design and to implement an alternative liquid-liquid extraction process for the alcohol recovery, were determined for seven ionic liquids. The modelling of the equilibrium data was performed using the COSMO-RS and NRTL models; the first aiming at screening other ionic liquids not experimentally studied, and the latter aiming at designing a separation process. The gathered data indicate that phosphonium-based ionic liquids are the best yet reported to perform water-ethanol separations. Based on the most promising phase diagrams, an analysis of the alcohol and ionic liquid recovery steps was carried out and a liquid-liquid extraction stage coupled to an extractive fermentation, where the ionic liquid is continuously recycled to the fermentator and the ethanol concentration is carried out by pervaporation, is here proposed as an alternative to distillation.
keywords
COSMO-RS; BINARY-SYSTEMS; ASYMMETRIC FRAMEWORK; MUTUAL SOLUBILITIES; PHASE-EQUILIBRIA; PREDICTION; ALCOHOLS; SOLVENTS; HEXAFLUOROPHOSPHATE; METHYLSULFATE
subject category
Chemistry; Science & Technology - Other Topics
authors
Neves, CMSS; Granjo, JFO; Freire, MG; Robertson, A; Oliveira, NMC; Coutinho, JAP
our authors
Catarina Maia Seco Seiça Neves
Assistant Researcher
Mara Guadalupe Freire Martins
Coordinating ResearcherGroups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
acknowledgements
The authors acknowledge financial support provided by Fundacao para a Ciencia e a Tecnologia (Portugal) through the project PTDC/QUI/72903/2008, post-doctoral grant SFRH/BPD/41781/2007 of M. G. Freire and the Ph.D. grants SFRH/BD/70641/2010 and SFRH/BD/64338/2009 of Catarina M. S. S. Neves and J. F. Granjo, respectively.