| The octanol-water (KOW) and tricaprylin-water partition coefficients (KTW) of seven chlorobenzenes (1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene) were measured by a conventional shake-flask, batch contacting method over the temperature range 5 to 45°C. The results agree well with available literature data obtained with comparable methods. The van't Hoff plots of log KOW versus reciprocal of temperature exhibit linearity with values of KOW increasing by 10%--14% over this temperature range. The enthalpy of phase change ranges from 17 to 24 kJ/mol. The KOW values from this study are also compared with values calculated from reported measurements of octanol-air partition coefficient (KOA) and air-water partition coefficient (KAW). The agreement between experimentally determined and estimated values of K OW are generally within 11%. This correlation approach can be important in estimating missing data for physical-chemical properties as required by the environmental fate models. The KTW values at 25°C are somewhat greater than corresponding KOW values. Larger deviations between KTW and KOW are observed for lower molecular mass chlorobenzenes. Generally, the differences are within 4%, with the exception of dichlorobenzenes, for which it was up to 10%. The values of log KTW are satisfactorily correlated in linear form with respective values of log KOW (from this work) as well as with reported values of triolein-water partition coefficients. The van't Hoff plots of log KTW versus reciprocal of temperature show linear behaviour with log KTW values increasing by 5%--8% over the temperature range (5 to 45°C). The enthalpy of phase change ranges from 9.7 to 16 kJ/mol. These data, which are regarded as more accurate than previous data will be of value for assessing the environmental fate of the chlorobenzenes, especially as a function of temperature.;As an illustration of the application of such physical-chemical property data, water quality models were developed for two large lakes in India namely Lake Nainital in the Central Himalayan region and Rihand Reservoir in east central India. The contaminants assessed were lead, copper, 1,4-di, 1,2,3,5-tera, penta-, and hexachlorobenzene, lindane, a -HCH benzo(a)pyrene, and benzo(b)fluranthene. Using reported and estimated data for emissions and lake characteristics, a steady state multi-segment QWASI fugacity model gave results which compared well with the reported concentrations. This model is viewed as possibly too complex for general use, especially in regions lacking a sophisticated infrastructure for environmental assessment. Accordingly, two simple models were developed and successfully applied to these chemicals. The role of such models for management of chemicals in developing regions is discussed. |
