Solubilities of Polychlorinated Biphenyls in Supercritical Carbon Dioxide

The solubilities of three solid polychlorinated biphenyls, 4,4′-dichlorobiphenyl, 2,3′,4′,5-tetrachlorobiphenyl, and 2,2′,3,3′,4,4′-hexachlorobiphenyI in supercritical carbon dioxide, have been measured at temperatures from 308.1 to 323.1 K and pressures from 90 to 480 atm. The data were obtained in a static apparatus with a high pressure equilibrium view cell which was tested by measuring the solubilities of pyrene in compressed carbon dioxide. The experimental solubility data were correlated with a compressed gas model using the Peng-Robinson equation of state and a volume based linear model which has been recently developed. The unknown critical properties of the polychlorinated biphenyl congeners were estimated using group contribution methods, and the vapor pressure data were determined by the modified Watson method. The solubilities ranged from 1.6 × 10^‒4 to 14 × 10^‒4 molar fraction for 4,4′-dichlorobiphenyl and 2,3′,4′,5-tetrachlorobiphenyl over the conditions studied. The solubilities for 2,2′,3,3′,4,4′-hexachlorobiphenyl were less than 2.6 × 10^‒4 molar fraction.