We have begun the characterization of aqueous choline chloride deep eutectic solvents (DES). The aqueous choline chloride DES were prepared in molar ratios of 1:1, 1:2, 1:4, 1:6, 1:8, and 1:10 choline chloride to water. Fourier transformed infra-red was used to identify new peaks that signaled bonds associated with eutectic formation. The first objective was to conduct thermal characterization of the aqueous DES mixtures prepared. The freezing points of all six DES samples were found to range between -54.7 oC to -65.7 oC in a dry ice freezing experiment. This is far below the crystallization temperature of -18 oC of choline chloride and freezing point of 0oC of water. Also, differential scanning calorimetric analysis (between -40 oC to 350 oC, ramp mode, heat rate 10 oC /min) using TA instrument Q200 series, determined that the minimum temperature of decomposition was 220 oC and the maximum was 240 oC. This was confirmed by Thermogravimetric analysis (TGA) which showed that at 240 oC, all water would have been lost. The TGA analysis also showed a two-phased degradation with the major one occurring at 220 oC – 240 oC and the minor degradation at around 320 oC. The mass loss during the major degradation is about 85% and the minor about 12 %. The research is on-going and we will continue with the characterization and explore possible applications of the aqueous choline chloride DES.

Characterization of aqueous choline chloride deep eutectic solvents

249th National Meeting (2015)

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