Determination and Estimation of Some Important Properties of Ammonium and Phosphonium Salt based Deep Eutectic Solvents

Abstract

iv newlineABSTRACT newlineDue to similar properties, Deep Eutectic Solvents (DESs) are analogous to ionic liquids (ILs). Due to the simple preparation steps and environmentally benign nature, DESs have gained much attention from researchers. The promising applications of DESs at an industrial scale include a variety of fields like extraction and separation, nanotechnology, bio-catalysis, reaction media, membrane technology, lubricants, metal processing, electrochemistry, and other applications. One of the reasons hindering the use of DESs for large industrial-scale applications is the scarce thermophysical properties database. newlineIn this regard, 45 DESs were synthesized based on varying molar ratios of hydrogen bond acceptors (choline chloride, methyl triphenylphosphonium bromide, and tetra-n-butylammonium bromide) and hydrogen bond donors (glycerol, ethylene glycol, and triethylene glycol). The thermophysical properties are essential for process design and extending the laboratory scale applications of DESs to large scale. The thermophysical properties like density, viscosity, conductivity, and surface tension were experimentally determined for a wide range of temperatures. The heat capacity database of 17-DESs as a function of temperature was collected from open literature. The main objective of the work was an experimental measurement and study of some fundamental thermophysical properties (density, viscosity, conductivity, heat capacity, and surface tension) of DESs. Also, to establish the correlation between the basic input parameters and these thermophysical properties by regressing the experimental data. Since the decade, the prediction of vital thermophysical properties has been aroused due to the urgent requirement to reduce the cost and time to experimental determination for DESs. Various empirical models were classified and studied over DESs based on the input requirements. The models were categorized as component-specific regression coefficient-based and molecular structure-based models. The molecular structure-based