Prediction of vapour pressures of chlorobenzenes and selected polychlorinated biphenyls using the COSMO-RS model

The applicability of the Conductor-like Screening Model for Real Solvents (COSMO-RS) for the prediction of the liquid phase vapour pressure of chlorobenzenes (CBzs) and polychlorinated biphenyls (PCBs) is presented. The liquid phase vapour pressures of 12 CBzs, biphenyl and 26 PCBs, and their enthalpies of vaporization derived from the temperature dependence of the predicted vapour pressure using the Clausius-Clapeyron equation. These predicted values using COSMO-RS method were compared not only with the literature data but also with the empirical vapour pressure data, obtained using the Knudsen effusion method in our previous papers. In general, COSMO-RS method successfully predicts the vapour pressures of CBzs and PCBs over a wide temperature range including room temperature. In particular, a good agreement was observed between the COSMO-RS predicted and experimental vapour pressures of low-chlorinated CBzs and non-ortho PCBs. For PCBs, the errors between the predicted and experimentally measured values were larger for the congeners that have more chlorine substitutions in the ortho-position. The Root Mean Square Errors (RMSEs) of the COSMO-RS predictions for CBzs, and the non-ortho, mono-ortho, di-ortho and tri-ortho congeners of PCBs were in the range of 0.035-0.539, 0.079-0.21, 0.28-0.58, 0.47-0.74 and 0.77-0.87, respectively.