Separation of biomass furans by terpenoid-based hydrophobic deep eutectic solvents probed by molecular dynamics simulations and liquid-liquid extraction experiments

Abstract

Preparing furfuryl alcohol from furfural using liquid-phase hydrogenation as a raw material contains a certain amount of furfuryl alcohol (FA) and furfural (FF) in the final process wastewater, which needs to be separated. This article uses FA and FF aqueous solutions as model wastewater and hydrophobic eutectic solvents (HDESs) as extractants. Nine HDESs are prepared with three terpene compounds and three fatty acids in different proportions. Liquid extraction experiments are carried out to determine the best HDESs for separating this wastewater. Furthermore, the optimal operating conditions were determined by changing the extraction temperature, the initial concentrations of FA and FF in the wastewater, and the amount of HDESs used. Simultaneously, the ability of hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD) to form hydrogen bonds and the affinity or repulsion between components were predicted using quantum chemistry (QC) calculations. The microscopic mechanism of action between HDES and the wastewater model was analysed using molecular dynamics (MD) simulation to study the effect of extraction conditions on the separation effect. Ultimately, the experimental results showed that the LLE of low-concentration (0.2 %) wastewater model with Mth-Dec (2:1) at 40 °C had a high extraction efficiency for FA and FF, which were 84.81 % and 87.49 %, respectively. The experimental results correspond to the high selectivity for FA and FF (3.30 and 3.88, respectively) in the molecular modelling results, indicating that the method proposed in this paper can be used to study related separation problems.