Abstract
The aqueous two-phase system (ATPS) based on ionic liquid (IL) has proven to have excellent extraction performance as a new extraction platform. Nevertheless, the regeneration, recovery and reuse of IL are still a big challenge. Developing a greener and more cost-effective extraction process is a daunting task. Aiming at overcoming this disadvantage, we innovatively proposed a IL-ATPS phase diagram which was formed from [C4mim][CF3SO3] and inorganic salts. The effects of phase-forming salt species and IL concentration on the distribution of syringic acid in IL-ATPS were investigated. The results displayed that the IL-ATPS extraction efficiencies of Na2SO4 and Na2CO3 performed best (96.66 ± 1.01% and 95.11 ± 0.87%, respectively). The IL-ATPS was then used in sequential cycles to assess their efficacy on the IL reusability. The syringic acid was extracted again using the recovered IL, and the extraction efficiency was 94.11 ± 1.06%. In addition, we tested the most prominent systems to extract caffeic acid which provided evidence for the back-extraction routes and the recyclability concept of the vast applicability of caffeic acid and the extraction efficiencies were higher than 96.43 ± 0.24%. This work can lay a good foundation for the sustainable development of IL-ATPS.
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•IL-ATPS based on [C4mim][CF3SO3] was constructed for extraction of syringic acid.•25 wt%[C4mim][CF3SO3] + 20wt%Na2SO4 extracted 96.66% syringic acid in IL phase.•20 wt%[C4mim][CF3SO3] + 10wt%Na2CO3 extracted 95.11% syringic acid in salt phase.•Back extraction and recyclable IL achieve more than syringic acid rate 94.11%.•The recyclable system to extract caffeic acid and the extraction rate can reach 96%.