Diffusion coefficients and Henry's constants of hydrofluorocarbons in [HMIM][Tf₂N], [HMIM][TfO], and [HMIM][BF₄]

A semi-infinite volume technique was used to measure the diffusion coefficients of six hydrofluorocarbons in three room-temperature ionic liquids in the temperature range from 303.2 K to 343.2 K. The Henry's constants were also determined at the same time. The hydrofluorocarbons are difluoromethane (R-32), pentafluoroethane (R-125), fluoroethane (R-161), 1,1,1-trifluoroethane (R-143a), 2,3,3,3-tetrafluoropropene (R-1234yf), and 1,1-difluoroethane (R-152a). The room-temperature ionic liquids are 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][Tf₂N]), 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([HMIM][TfO]), and 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM][BF₄]). The diffusion coefficients and the Henry's constants of hydrofluorocarbons in the three RTILs all increase with the increasing temperature, but the orders of them are different. In addition, the relationship between the diffusion coefficient and the Henry's constant was investigated. Finally, the Wilke-Chang equation was successfully applied to correlate the diffusion coefficients of hydrofluorocarbons in room-temperature ionic liquids.