Densities, Viscosities, and CO2 Solubility in [C4mim][TFSA]–Diglyme Mixtures

Abstract

The densities and viscosities of mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C₄mim][TFSA]) with diethylene glycol dimethyl ether (diglyme) were measured over the temperature range from 273.15 to 333.15 K. The excess molar volumes and viscosity deviations were determined from the density and viscosity data. Both excess molar volumes and viscosity deviations showed negative values over the entire composition range. The magnitude of the excess molar volumes increased slightly with increasing temperature, whereas that of the viscosity deviations increased remarkably with decreasing temperature. The mole-fraction-scaled solubilities of CO₂ in four [C₄mim][TFSA]–diglyme mixtures were measured at 313.15 K, together with the saturated liquid densities. The CO₂ concentration per liquid volume increased with increasing diglyme content, particularly in the diglyme-rich region. The relative volume changes and apparent molar volumes of CO₂ indicated that the volumetric behavior upon CO₂ absorption depends on both the amount of absorbed CO₂ and the liquid composition.