Evaluation of hybrid solvents featuring choline chloride-based deep eutectic solvents and ethanol as extractants for the liquid–liquid extraction of benzene from n-hexane: towards a green and sustainable paradigm

Abstract

Deep eutectic solvents (DESs) have high viscosities, but known to be mitigated by addition of suitable co-solvent. The effect of such co-solvent on the extraction efficiency of the hybrid solvent is hardly known. This study examined the effect of ethanol on three choline chloride-based DESs (glyceline, reline, and ethaline) by mixing each in turn with ethanol in various volume proportions. The hybrid solvents were evaluated for the extraction of benzene from n-hexane. Pseudo-ternary liquid–liquid equilibrium data were obtained using the refractive index method at 303 K and 1 atm for the systems, n-hexane (1) + benzene (2) + hybrid solvent (glyceline/ethanol, ethaline/ethanol, reline/ethanol) (3), and used to evaluate distribution coefficient (D) and selectivity (S). Furthermore, the physicochemical properties of the hybrid solvents were also determined. The results indicate increase in selectivity with increasing ethanol addition up to 50% and decrease with further addition. All hybrid solvents with 50% ethanol outperform sulfolane and are suitable replacement for same as green and sustainable extractant for aromatics from aliphatics. The glyceline + 50% ethanol emerged the overall best with 49.73% elevation in selectivity and 41.15% reduction in viscosity relative to the neat glyceline. The finding of this study is expected to fillip the drive for paradigm shift in petrochemical industries.

Investigation of the effects of ternary deep eutectic solvent composition on pretreatment of sorghum stover

“…The addition of the co‐solvent with a certain range of molar ratios between the co‐solvent and IL decreased the fraction of free ions in the system rather than promoting the dissociation of the IL. In another previous study, ethanol‐incorporated ChCl‐polyol DES systems showed higher solubility of aromatics compared with the binary DES 37 . Since ethylene glycol leads to higher lignin solubility than water, higher delignification with ChCl‐DHBA‐EG was expected.…”

“…In another previous study, ethanol-incorporated ChCl-polyol DES systems showed higher solubility of aromatics compared with the binary DES. 37 Since ethylene glycol leads to higher lignin solubility than water, higher delignification with ChCl-DHBA-EG was expected.…”