Ionic liquids as a novel class of electrolytes in polymeric aqueous biphasic systems

Abstract

The use of ionic liquids (ILs) as electrolytes in aqueous biphasic systems (ABS) composed exclusively ofpolymers and their application to the extraction of biomolecules is here studied. The binodal curves ofthe quaternary systems formed by polyethylene glycol (PEG 8000), sodium poly(acrylate) (NaPA 8000),water and ILs or inorganic salts as electrolytes are established. These systems enable the assessment ofthe influence of the salt nature, chemical structure and concentration on the two-phase formation. Thesesystems were characterized regarding the pH and the ILs’ partition between both phases. Moreoverthe extractive potential of these ABS is evaluated using the protein cytochrome c (Cyt c) and the dyechloranilic acid (CA). The main results on the extraction efficiencies show that Cyt c is recovered in theNaPA 8000-rich phase (EECyt c> 96.13 ± 3.22%), while CA preferentially migrates towards the PEG 8000-rich phase (EECA> 80.13 ± 1.45%). The optimal electrolyte concentration in the CA partition was found tobe the lowest possible, i.e. 0.1 wt%, as it leads to a remarkable increase in the partition coefficient of CA(KCA) towards the PEG 8000-rich phase. These results indicate that this class of polymeric ABS may be anadvantageous tool in the development of novel extractive platforms