LABORATORY MEASUREMENTS OF THE AQUEOUS SOLUBILITY OF MIXTURES OF CHLORINATED SOLVENTS

This article describes the results of laboratory batch solubility experiments with five chlorinated solvents (chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene) present alone or in binary or ternary mixtures. The measured aqueous solubility values of the pure compounds revealed significant deviation from the widely used literature values for trichloroethylene and tetrachloroethylene. The experiments with binary and ternary solvent mixtures showed that the chlorinated solvents used in this study exhibited close to ideal behaviour. That means the concentration of an organic compound in the aqueous phase in equilibrium with an organic phase can be described as the mole fraction in the organic phase times the aqueous solubility of the pure compound. The UNIFAC (universal quasi chemical functional group activity coefficients) method was used in this study to estimate the appropriate activity coefficients for the experiments with binary mixtures. The UNIFAC method predicted nonideal behaviour for some of the mixtures. However, the deviation was only significant at relatively low mole fractions. Experiments indicated that the assumption of ideal behaviour for the chlorinated solvents used in this study is a reasonable one. The assumption of ideal behaviour simplifies the use of models to simulate the dissolution of chlorinated solvent mixtures in ground water.