abstract
Extractive fermentation using aqueous biphasic systems (ABS) is a promising separation process since it provides a nondenaturing environment for biomolecules and improves the stability of cells. Due to environmental concerns and toxicity issues related with common volatile organic solvents, ionic liquids (ILs), a new class of nonvolatile alternative solvents, are being currently investigated for extraction purposes. In this work, a wide range of imidazolium-based ILs was studied aiming at obtaining new insights regarding their ability toward the formation of ABS and their capacity to the extraction of biomolecules. On the basis of the IL cations 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, the IL anion influence on ABS formation was assessed through their combination with chloride, bromide, acetate, hydrogensulfate, methanesulfonate, methylsulfate, ethylsulfate, trifluomethanesulfonate, trifluoroacetate, and dicyanamide. Ternary phase diagrams (and respective tic-lines) formed by these hydrophilic ILs, water, and the inorganic salt K(3)PO(4), were measured and are reported. The results indicate that the ability of an IL to induce ABS closely follows the decrease in the hydrogen bond accepting strength or the increase in the hydrogen bond acidity of the IL anion. In addition, the extraction capacity of the studied ABS was evaluated through their application to the extraction of an essential amino acid, L-tryptophan. It is shown that the partition coefficients obtained between the IL and the K(3)PO(4)-aqueous rich phases were substantially larger than those typically obtained with polymers-inorganic salts or polymers-polysaccharides aqueous systems.
keywords
2-PHASE SYSTEMS; PHASE-BEHAVIOR; MUTUAL SOLUBILITIES; POLYETHYLENE-GLYCOL; PLUS SUCROSE; SALTING-OUT; TEMPERATURE; WATER; FERMENTATION; POLARITY
subject category
Chemistry
authors
Ventura, SPM; Neves, CMSS; Freire, MG; Marrucho, IM; Oliveira, J; Coutinho, JAP
our authors
Catarina Maia Seco Seiça Neves
Assistant Researcher
Isabel Maria Delgado Jana Marrucho Ferreira
Full professor
Mara Guadalupe Freire Martins
Coordinating Researcher
Sónia Patrícia Marques Ventura
Assistant ProfessorGroups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
acknowledgements
The authors are grateful for financial support from Fundacao para a Ciencia e a Tecnologia for the project PTDC/EQU-FTT/65252/2006 and Ph.D. grants SFRH/BD/37830/2007 of Sonia P.M. Ventura and postdoctoral grant SFRH/BPD/41781/2007 of Mara G. Freire.