(224c) Thermodynamic and Transport Properties of Ionic Liquid/Water Mixtures Used in Biomass Dissolution

An increased demand for alternative biofuel synthesis and biorenewable chemical intermediates currently exists. Certain ionic liquids (ILs) have the capability of dissolving large amounts of biomass. The ionic liquids must be tailored such that they can disrupt the complex structure within cellulose formed by strong intermolecular and intramolecular hydrogen bonding among the glucose units. The ILs capable of high levels of cellulose dissolution are almost exclusively hydrophilic. Furthermore, water has been proposed as a potential anti-solvent used to precipitate amorphous cellulose from the mixture post-dissolution. We examine the effects of water content on the extent of solvation in IL/cellulose mixtures. Knowledge of the thermodynamic and transport properties of the utilized ILs at varying water compositions is essential for unit design and assessment of economic feasibility. This study reports on the viscosity, density, Fickian diffusion coefficient, and solubility of water in two ionic liquids proposed for the dissolution of cellulose ‒ 1-ethyl-3-methylimidazolium diethyl phosphate and 1-hexyl-3-methylimidazolium chloride. Moreover, modeling techniques for solubility of water in the ILs as well as the excess heats of solution are presented. A hypothetical process feasibility assessment is reported.