Using Ionic Liquids To Tune the Performance of Aqueous Biphasic Systems Based on Pluronic L-35 for the Purification of Naringin and Rutin

abstract

Aqueous biphasic systems (ABS) based on Pluronic L-35, a (EO)(x)-(PO)(y)-(EO)(x), triblock copolymer, were determined and applied in the separation of two structurally similar flavonoids (naringin and rutin). Two sets of phase formers were paired with Pluronic L-35, one comprising conventional salts/buffer and other including cholinium-based ionic liquids (ILs). It is shown that while the conventional salts induce an unbalanced and strong salting out leading to complete extraction of flavonoids to the same phase in most of the cases (84.7 +/- 0.6% <= R-NAR <= 100% and 53.2 +/- 0.5% <= R-RUT <= 99.7 +/- 0.1% with selectivities ranging from 1 to 11.8), the cholinium-based ILs provide an enhanced extractive performance. Indeed, these novel cholinium ILs/Pluronic L-35-based ABS allowed the manipulation of the affinity of both naringin and rutin to opposite phases, thus yielding a selective separation. The best results were achieved for the system using [Ch][Bic] as phase former (R-NAR = 89.6 +/- 0.3 and R-RUT = 32 +/- 2 with a selectivity of 18.9). An integrated approach based on the sequential implementation of Na2SO4/Pluronic L-35- (step 1) and [Ch][Bic]/Pluronic L-35-based (step 2) ABS was designed to purify the flavonoids from a complex synthetic mixture simulating natural extracts. Remarkably, glucose (the main contaminant) was removed during step 1 with an extraction efficiency of 60 +/- 4% to the Na2SO4-rich phase, while step 2 has enabled the efficient separation of naringin from rutin.

keywords

2-PHASE SYSTEMS; BLOCK-COPOLYMERS; TRIBLOCK COPOLYMERS; MOLECULAR-INTERACTIONS; DIFFERENT TEMPERATURES; DIALYSIS MEMBRANE; PHASE-EQUILIBRIUM; EXTRACTION; FLAVONOIDS; SEPARATION

subject category

Chemistry; Science & Technology - Other Topics; Engineering

authors

Silva, FAE; Carmo, RMC; Fernandes, APM; Kholany, M; Coutinho, JAP; Ventura, SPM

Groups

G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

Projeto de Investigação Exploratória: Sónia Patricia Marques Ventura (IF/00402/2015)

EXIL - Exchange on Ionic Liquids (EXIL)

MultiBiorefinery - Multi-purpose strategies for broadband agro-forest and fisheries by-products valorization: a step forward for a truly integrated biorefinery (SAICTPAC/0040/2015)

acknowledgements

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement. This work was partly financed by the FCT project SAICTPAC/0040/2015. F.A.e.S. acknowledges FCT for the financial support from her doctoral scholarship SFRH/BD/94901/2013. S.P.M.V. acknowledges FCT for the IF contract IF/00402/2015. The authors would like to acknowledge COST for funding STSM within CM1206 action (ref. COST-STSM-ECOST-STSM-CM1206-200114-040305).