(466g) COSMO Screening of Hydrophobic Deep Eutectic Solvents for Platform Chemical Extraction from Water

Platform chemicals are value-added products from the biomass processing industries. Platform chemicals are generally produced in an aqueous solution which can be difficult to retrieve from due to their tendency for condensation at high concentrations. Using common thermal separation techniques causes polymerization among platform chemicals which makes liquid-liquid extraction favorable. In contrary, hydrophobic deep eutectic solvents (HDES) have been shown to be highly efficient at extracting platform chemicals from aqueous solution. HDES are relatively cheap, non-toxic, and environmentally benign, which make them excellent candidates for separating platform chemicals from water. Very few experimental studies have been conducted on the application of HDES in platform chemical extraction. This study looks at a comprehensive sample size of HDES (>100 solvents) and the driving forces of absorbance and selectivity for three representatives of platform chemicals: hydroxymethyl furfural, levulinic acid, and sorbitol. These three represent the three classes of platform chemicals of furan, acids, and alcohols. A conductor like screening model (COSMO) is adopted to screen suitable hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD) for platform chemical extraction based on hydrogen bond properties using a triple-zeta valence polarization (TZVP) basis set. This model is evaluated compared to literature experimental studies to verify integrity of the results. It has been found that HDES with strong preference for vander Waals interactions have the highest selectivity for the platform chemicals over water. The HDES that have hydrogen bonding capabilities have a less selectivity for separating the analytes from water. These observations correspond with solvent characteristics of alkyl chain length, polarizability, and resonance structure. From the results of the binary solvents, ternary solvents were examined for synergistic effects of selectivity and absorptivity. The results of this were preferential to the acidic platform chemicals since they have a higher affinity for water than the others.