abstract
Herein we demonstrate the formation of new stimuli-responsive aqueous biphasic systems (ABS), able to respond simultaneously to temperature and pH, or just to one stimulus, therefore allowing the design of more sustainable separation processes. This dual behavior is achieved with ABS formed by mono- or dicationic protic ionic liquids as phase-forming components, being defined by the ionic liquid cation chemical structure or its basicity. While ABS comprising monocationic ionic liquids only respond to the effect of temperature, systems comprising dicationic ionic liquids are simultaneously affected by both temperature and pH variations. Dicationic ionic liquids are here identified as the key to unlock a double response to stimuli, which is due to the presence of two pKa values afforded by the cation. The reported findings contribute to increase the customizability of double stimuli-responsive ABS based on ionic liquids, whose development was up to date limited to ionic liquids bearing pH-responsive anions, opening the door towards the development of more sustainable separation processes.
keywords
SEPARATION; EXTRACTION; SALTS
subject category
Chemistry
authors
Rufino, AFCS; Capela, EV; Quental, MV; Coutinho, JAP; Vranes, MB; Gadzuric, SB; Silva, FAE; Freire, MG
our authors
Ana Filipa Correia Santos Rufino
PhD Student
Ana Francisca Osório de Almeida Coelho e Silva
Junior Researcher
Emanuel V. Capela
Junior Researcher
Mara Guadalupe Freire Martins
Full professor
Maria João Quental
Post-Doc FellowshipGroups
G1 - Porous Materials and Nanosystems
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
Projects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MEC (PIDDAC) and EXPL/BII-BTI/0731/2021 (DOI 10.54499/EXPL/BII-BTI/0731/2021), financed by national funds (OE), through FCT/MCTES. The NMR spectrometers are a part of the National NMR Network (PT NMR) and are partially supported by the Infrastructure Project No. 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL, and FCT through PIDDAC). A.F.C.S. Rufino and F.A. e Silva acknowledge FCT for the PhD grant SFRH/BD/138997/2018 and for the researcher contract CEECIND/03076/2018/CP1559/CT0024 (DOI 10.54499/CEECIND/03076/2018/CP1559/CT0024) under the Scientific Employment Stimulus-Individual Call 2018, respectively.