Operational Strategies and Comprehensive Evaluation of Menthol Based Deep Eutectic Solvent for the Extraction of Lower Alcohols from Aqueous Media

Deep Eutectic Solvents (DESs) are gaining more interest as low-cost extraction media. Looking at its vast opportunity, the current work explores the extraction of alcohols namely ethanol, 1-propanol, and 1-butanol from the aqueous phase using two novel hydrophobic DES at 303.15 K and 1 atm. The preparation of DES possess a common HBA (Hydrogen Bond Acceptor) with a HBD (Hydrogen Bond Donor such as organic acids i.e., lauric acid and decanoic acid) at a certain proportion. Ratios of 2:1 and 1:1 were used for synthesizing menthol: lauric acid (DES-1) and menthol/decanoic acid (DES-2), respectively. The highest extraction efficiency of alcohols was observed in the presence of DES-1. Thereafter, atomistic molecular dynamics (MD) simulations have also been adopted to understand the extraction mechanism of alcohols from water using these DES. From MD simulations, the interaction energies, structural properties such as radial and special distribution functions, and dynamic properties such as self-diffusivity are computed. From the results of MD simulations, it was inferred that menthol or the HBA was playing a vital role in the extraction of alcohols as compared lauric acid or decanoic acid. Furthermore, a process flow sheet was conceptualized for the separation and recycling of both DES and alcohol using ASPEN plus. It yielded a 99.7% and 98.3% recovery of DES and alcohol, respectively.