Solubility and Diffusivity of Bromodifluoromethane (Halon-1201) in Imidazolium Ionic Liquids: [C₂C₁im][Tf₂N], [C₄C₁im][BF₄], and [C₄C₁im][PF₆]

The solubility and diffusivity of bromodifluoromethane (CHF₂Br, Halon-1201) were measured in three ionic liquids (ILs), [C₂C₁im]­[Tf₂N], [C₄C₁im]­[BF₄], and [C₄C₁im]­[PF₆], using an intelligent gravimetric analyzer (IGA) gravimetric microbalance. The experimental absorption and desorption measurements were conducted at temperatures between 283.2 and 348.2 K and pressures ranging from 0.0250 to 0.4000 MPa. Temperature dependent nonrandom two-liquid activity coefficients and infinite dilution Henry’s Law constants were fit to the experimental solubility data, while the Halon-1201 enthalpy (H̅_sol) and entropy (ΔS̅_sol) of solution were calculated using van’t Hoff relationships. Kinetic absorption data collected by the IGA microbalance at one-second intervals were used to calculate the diffusion coefficient of Halon-1201 in each IL. Finally, the hydrodynamic radius of Halon-1201 was calculated using the Stokes–Einstein relationship. The experimental results for bromodifluoromethane are compared to previous studies on trifluoromethane, chlorodifluoromethane, and other fluorocarbon gases to investigate the impact of atom substitution on fluorocarbon solubility.