Correlations of Henry's Law Gas–Solid Virial Coefficients and Chromatographic Retention Times for Hydrocarbons and Halocarbons Adsorbed on Carbopack C Carbon

Abstract

Second gas–solid virial coefficients were determined at 403.5 ± 0.5 K for 6 adsorbates, including butane, chloroform, trichlorofluoromethane (Freon 11), bromochloromethane, 1-chloro-2-methylpropane, and dibromodifluoromethane. For another 11 adsorbates, including dichlorodifluoromethane (Freon 12), chlorodifluoromethane (Freon 22), methyl chloride, methylene chloride, propane, n-pentane, n-hexane, carbon tetrachloride, 1,2-dichloropropane, butyl chloride, and cyclohexane, B2s was measured over a range of temperatures between 308 and 494 K. These values were found using gas–solid chromatography with Carbopack C (Supelco Inc.), a graphitized carbon black powder, as the adsorbent. We find that both the ln B2s values and the gas–solid interaction energies are effectively correlated with adsorbate-calculated molar refractivity, r2 = 0.947 and r2 = 0.964, respectively. Dipole moment alone provides a nearly random correlation of ln B2s and, if used with molar refractivity, gives r2 = 0.970 for the 17 hydrocarbon and alkyl halide (halocarbon) adsorbates. A theoretical equation was developed that predicts a quantitative structure retention relationship (QSRR) used to correlate ln B2s values with molar refractivity. B2s values are directly proportional to the retention times of the adsorbates. Using one-surface and two-surface models, a calculation of the surface area of the Carbopack C for each of the 17 adsorbates provided a check on the consistency of the analysis as the adsorbate was varied.