abstract
The main objective of the present work is to study the application of ionic liquids (ILs) in the formation of aqueous two-phase systems (ATPS) and to evaluate their capability in the extraction of bioactive compounds. This study is essentially focused on the finding of more benign systems, making use of organic salts, and in the gathering of a deeper understanding on the mechanisms which rule the partitioning of biomolecules between the coexisting phases of ATPS. IL-based ATPS display a widespread applicability in the extraction and purification of a large range of compounds, while preserving their characteristics. Thus, with the purpose of fostering the studies conducted in this area and to improve the performance of these systems, this work starts with the characterization of ATPS composed of several ILs and the organic salt potassium citrate. The selected ILs allowed the study of the effect of the anion nature and cation core towards the phase diagrams behavior. Additionally, it was analyzed the influence of the imidazolium cation alkyl side chain length, as well as the pH, in the formation of these systems. The extraction of a series of alkaloids was carried out not only to verify the applicability of ATPS formed by imidazolium-based ILs and an organic salt, but also to study the effect of the ILs self-aggregation and subsequent impact on the partitioning pathway of different biomolecules. The obtained results show that the self-aggregation of ILs has a significant effect and allows tailored extractions. Finally, the actual applicability of IL-based ATPS in the extraction and concentration of compounds of human concern from biological fluids was investigated. Usually, the low concentrations of bisphenol A, an endocrine disruptor, in human fluids make it difficult to detect via conventional techniques. The effect of the IL cation core was investigated and the extraction conditions were optimized. The results showed a high extraction efficiency and concentration up to 100-fold of bisphenol A from biological fluids.
subject category
Chemical Engineering
authors
Helena Passos
our authors
Helena Isabel Sousa Passos
Junior Researchersupervisors
João A. P. Coutinho and Mara G. Freire