Solubility and diffusivity of difluoromethane in room-temperature ionic liquids

New experimental results are presented for the solubility and diffusivity of difluoromethane in 19 room-temperature 14 ionic liquids (RTILs). In the series of RTILs presented here, eight RTILs with five new fluorocarbon sulfonate anions have been prepared for the first time. The measurements were performed using a gravimetric microbalance at temperatures between (283.15 and 348.15) K and at pressures from (0.01 to 1.0) MPa. Experimental gas solubility data were successfully correlated with the nonrandom two-liquid (NRTL) solution model. The solubility of difluoromethane in RTILs is affected by the choice of both the cation and anion. Diffusivities obtained from the time-dependent absorption data were well analyzed using a model based on a modified Stokes-Einstein equation. The calculated molecular size for difluoromethane is 2 to 3 times larger than the known size.