Temperature dependence of henry's law constants for selected chlorobenzenes, polychlorinated biphenyls and polycyclic aromatic hydrocarbons

Abstract

Modeling the fate of organic micropollutants in aquatic systems requires information about gas/water partitioning at environmental temperatures. In this paper experimental data are presented on Henry's law constant (H) for seven chlorobenzenes, three polychlorinated biphenyl (PCB) congeners, and six polycyclic aromatic hydrocarbons (PAHs). The studied compounds were 1,2,3–; 1,2,4– and 1,3,5–tri–; 1,2,3,4– and 1,2,3,5–tetra–; penta–; and hexachlorobenzene; 2–5–di–; 2,4,4′–tri-; and 2,2′5,5′–tetrachlorobiphenyl; and the PAH compounds fluoranthene, benzo[b]flu-oranthene, benzo[kfluoranthene, benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3–cd]pyrene. H was measured in a buffer solution using a modified gas-purge technique. Values for this set of PAH compounds have not been determined experimentally before. The temperature dependence of H was measured for the tetra-, penta-, and hexachlorobenzenes and for all PCBs and PAHs over a temperature range of 10 to 55°C. The experimental data and temperature dependence are in good agreement with partitioning theory and available literature data. The observed temperature dependence results in a doubling of H for every 10°C temperature increase.