Effect of Ethylene, Diethylene, and Triethylene Glycols and Glycerol on the Physicochemical Properties and Phase Behavior of Benzyltrimethyl and Benzyltributylammonium Chloride Based Deep Eutectic Solvents at 283.15-343.15 K

Deep eutectic solvents (DESs) are regarded as a promising and emerging alternative for volatile organic compounds (VOCs) due to their cost-effectiveness and environmentally sustainable nature. Formulation of new DESs and thorough investigation of their physicochemical properties have been on the rise ever since potential applications of DES have been realized. The present study reports a new series of DES based on benzyltrimethylammonium chloride and benzyltributylammonium chloride as hydrogen bond acceptor (HBAs) with three ethylene glycols and glycerols as hydrogen bond donors (HBDs). The current work includes the synthesis, characterization, and investigation of the thermophysical properties of a series of DES systems. The studied properties include density, rho, speed of sound, u, viscosity, eta, refractive index, n(D), and electrical conductivity, sigma, for all DESs in the temperature range from 283.15 to 343.15 K. The observed trends in properties like density, speed of sound, viscosity, and refractive indices were correlated with appropriate equations, and some industrially useful parameters have also been derived. An insight about the internal association in these DESs has been analyzed through the rheological and Fourier-transform infrared (FT-IR) spectroscopy. The newly synthesized DESs have also been investigated for their efficiency in aqueous biphasic system (ABS) formation. This systematic study revealed the influence of both HBD/HBA and temperature on the physicochemical characteristics of the DESs.