Aromatic volatile organic compounds absorption with phenyl-based deep eutectic solvents: A molecular thermodynamics and dynamics study

The suitability of phenyl-based deep eutectic solvents (DESs) as absorbents for toluene absorption was investigated by means of thermodynamic modeling and molecular dynamics (MD). The thermodynamic models perturbed-chain statistical associating fluid theory (PC-SAFT) and conductor-like screening model for real solvents (COSMO-RS) were used to predict the vapor–liquid equilibrium of DES–toluene systems. PC-SAFT yielded quantitative results even without using any binary fitting parameters. Among the five DESs studied in this work, [TEBAC][PhOH] consisting of triethyl benzyl ammonium chloride (TEBAC) and phenol (PhOH), was considered as the most suitable absorbent. Systems with [TEBAC][PhOH] had lowest equilibrium pressures of the considered DES–toluene mixtures, the best thermodynamic characteristics (i.e., Henry's law constant, excess enthalpy, Gibbs free energy of solvation of toluene), and the highest self-diffusion coefficient of toluene. The molecular-level mechanism was explored by MD simulations, indicating that [TEBAC][PhOH] has the strongest interaction of DES–toluene compared to the other DESs under study. This work provides guidance to rationally design novel DESs for efficient aromatic volatile organic compounds absorption.