Gas Solubility and Rheological Behavior of Natural Deep Eutectic Solvents (NADES) via Combined Experimental and Molecular Simulation Techniques

A potential of natural deep eutectic solvent (NADES) produced with the mixture of choline chloride with lactic acid, malic acid, citric acid and fructose is studied in this work. Experimental techniques are used to collect thermophysical property data including water content, thermal strength, density and gas solubility of CO2 and N-2 data at pressures up to 50 bars. Detailed rheological measurements and various models have been studied to describe the dynamic flow behavior. Moreover, a density functional theory (DFT) and classical molecular dynamics (MD) methods have been used for investigating the physicochemical properties, structuring, dynamics and interfacial behavior of the studied NADES from the nanoscopic point of view to infer its viability for extensive usage. The rheological experimental results show usual shear-thinning effect in which the is decreasing with shear rate at all temperatures. A trend of studied NADES viscosity profiles were found as very similar to that of common ionic liquids that were previously, where the viscosities of all studied NADES decreased with increasing temperature. DFT simulations yielded with an accurate quantification of short-range interaction but liquid state is also characterized by middle and long-range interaction together with volumetric effects. Molecular orientations were quantified by radial distribution functions and the developed interactions are topologically characterized.