AbstractPermeabilities and diffusivities of methyl chloride and benzene vapors at low activities in FEP Teflon membranes were measured in a continuous‐flow permeation cell, at temperatures ranging from 47°C to 150°C. In all cases investigated, the permeabilities and diffusivities were independent of the penetrant partial pressure, and the permeation process was well described by a Henry's law sorption–Fickian diffusion model. The activation energies for permeation and diffusion and the sorption enthalpy were respectively 34.8 kJ/mol, 50.1 kJ/mol, and −15.3 kJ/mol for methyl chloride and 49.5 kJ/mol, 69.1 kJ/mol, and −19.6 kJ/mol for benzene. The diffusional activation energies for these two substances and other low molecular weight hydrocarbons correlate reasonably well with the Lennard–Jones collision diameters of the penetrant molecules. The solubilities correlate approximately with the penetrant boiling points, but the highly polar nature of methyl chloride and the aromaticity of benzene lead to deviations between the solubilities of these substances and those of nonpolar aliphatics with the same tendency to condense from the
展开▼
