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Keys for Bioethanol Production Processes by Fermentation and Ionic Liquid Extraction

Pérez de los Ríos, Antonia, Hernández-Fernández, Francisco José, Zapata Henríquez, Patricio Alfredo, Missoun, Fatiha, Hernández-Fernández, Jesús, Ortiz-Martínez, Víctor, Salar-García, María José, Lozano Blanco, Luis Javier, Godínez, Carlos
ACS sustainable chemistry 2017 v.5 no.8 pp. 6986-6993
Saccharomyces cerevisiae, aqueous solutions, biocompatibility, bioethanol, biomass, bromides, chlorides, distillation, drying, ethanol, ethanol production, fermentation, ionic liquids, microbial growth
Bioethanol is produced by fermenting biomass. However, the main drawback of this process is the high purification costs involved, which are due to the energy-intensive distillation step and a drying step if high ethanol purity is required. This work evaluates an alternative separation–purification process for the production of ethanol, in which an ionic liquid is used to develop an integrated extraction–fermentation process. The capacity of ionic liquids to extract ethanol from an ethanol aqueous solution and their biocompatibility with Saccharomyces cerevisiae was analyzed. Ethanol extraction percentages ranging from 33% to 62% were obtained with the following water insoluble ionic liquids: [EPy⁺][NTf₂–] < [MTOA⁺][NTf₂–] < [OMIM⁺][BF₄–] < [Hex₃TDP⁺][dca–] < [Hex₃TDP⁺][Br–] < [ Hex₃TDP⁺][Cl–]. These ionic liquids could be used for in the postfermentation step of extraction. To evaluate the potential use of these ionic liquids as extraction phase in an integrated reaction/separation process, their biocompatibility with S. cerevisiae was analyzed. Of the above ionic liquids, [MTOA⁺][NTf₂–], [BMIM⁺][NTf₂–], [OMIM⁺][NTf₂–], [BMIM⁺][PF₆–] and [Hex₃TDP⁺][Cl–] were found to be biocompatible with S. cerevisiae because they allowed bacterial growth. From the extraction and biocompatibility tests, it can be concluded that [MTOA⁺][NTf₂–] and [Hex₃TDP⁺][Cl–] would be suitable for an integrated extraction-fermentation process for ethanol production.