Experimental study and thermodynamic modeling of phase equilibria of systems containing cyclohexane, alcohols (C4 and C5), and deep eutectic solvents

Abstract

Liquid-liquid equilibrium (LLE) data were measured and comparatively analyzed for six ternary mixtures of (cyclohexane + alcohols + deep eutectic solvents) at T = 298.2 K and p = 101 kPa. In this work, three choline chloride-based deep eutectic solvents (ChCl-DESs) were prepared for the extraction of the two structurally similar primary alcohols (1-butanol and 3-methyl-1-butanol) from a hydrocarbon (cyclohexane). The chosen DESs were DES1 (ChCl-propylene glycol with molar ratio = 1:3), DES2 (ChCl-ethylene glycol with molar ratio = 1:2), and DES3 (ChCl-glycerol with molar ratio = 1:2). The quality of the tie-line compositions was checked using the Othmer-Tobias correlation equation. The NRTL model was successfully applied to fit the experimental equilibrium data. The model binary interaction parameters were optimized by the Particle Swarm Optimization (PSO) algorithm. The model validation confirms that all the calculated parameters are consistent with the experimental data. Evaluation of the capacities of the deep eutectic solvent was carried out via the calculation of solute distribution coefficients and selectivity from the LLE data. The influence of the chemical structure of the alcohol on the phase equilibria was investigated. The extraction ability of the studied deep eutectic solvents displays promising results. The highest solute distribution coefficients were determined for (cyclohexane + 1-butanol + DES1).