Certain ionic liquids possess some of the highest known solubilities of carbohydrates such as cellulose, glucose, etc.  As the carbohydrates are non-volatile, anti-solvent techniques are most often used for the separations from the ionic liquids.  Certain organic solvents in addition to water act as anti-solvents that precipitate cellulose.  We present experimental solid-liquid phase equilibrium data illustrating how often only small amounts of these anti-solvents are needed to decrease significantly the saturation conditions. Some polar aprotic solvents, such as DMSO, DMF, etc., have little cellulose solubility themselves, but often have little reduction of cellulose solubility and could be considered co-solvents.  We show that the presence of these co-solvents significantly improves the transport properties (viscosity, etc.) of the mixture.  Glucose can also be separated from ionic liquids using various anti-solvents, however, now water becomes one of the few co-solvents for glucose dissolution.  In addition to organic anti-solvents, we demonstrate a novel use of compressed CO2 that can also be used as a reversible anti-solvent for both cellulose and glucose under certain conditions.  In order to understand the solvent environments especially near these phase-transitions (precipitations), various spectroscopic techniques will be employed.  These techniques will illustrate how the local solvent environment changes with composition of the anti-solvent.

Local solvent environment and phase equilibrium of ionic liquids and dissolved carbohydrates with conventional and novel antisolvents

248th National Meeting (2014)

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