Development and characterization of new extraction platforms using ionic-liquid-based aqueous biphasic systems
authors Helena Passos
supervisors João A. P. Coutinho and Mara G. Freire
thesis type PhD thesis
nationality International
author keywords aqueous biphasic systems, ionic liquids, extraction, characterization, ternary and quaternary systems, mixtures, polarity
abstract Due to their unique properties, being one of the most important their tailoring ability, ionic liquids (ILs) have been investigated in several fields and proposed as alternatives to hazardous volatile organic compounds commonly used by industries. In addition to the use of hydrophobic ILs in the formation of biphasic systems with water and/or in aqueous media, in the past decade, hydrophilic ILs were introduced as phase-forming components of aqueous biphasic systems (ABS) – more benign liquid-liquid systems composed of two aqueous- rich phases – able to provide improved extraction performance with increased selectivity for a large range of compounds. Based on these advantages, this thesis aims to gather a deeper scientific and technological knowledge on IL- based ABS, through the development and characterization of novel and more efficient separation processes. Aiming at developing ABS with tailored and better extraction performance, this work starts with a comprehensive investigation on the use of new phase- forming components and their mixtures, and their impact on the formation of liquid-liquid systems. The characterization of the properties of the coexisting phases and the description of the mechanisms which rule the formation of IL- based ABS, as well as the partition behavior of several solutes between the phases, are addressed in the second chapter. Finally, the use of these novel IL-based systems in the extraction and pre-concentration of compounds of human and environmental concern is addressed as a main example of these systems applications. The high versatility of IL-based ABS, as well as their high extraction performance and selectivity, were here demonstrated, confirming their potential within separation processes. Nevertheless, and as proved in this work, additional research on IL-based ABS is still required so that these systems can be finally scaled-up and used by industries.
year published 2017
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