SOLUBILIZATION OF TRICHLOROETHYLENE BY N-HEXADECYLPYRIDINIUM CHLORIDE MICELLES

An automated vapor pressure method has been used to obtain solubilization isotherms for trichloroethylene (TCE) in N-hexadecylpyridinium chloride (CPC) micelles, throughout a wide range of solute activities and at temperatures varying from 15 to 45 degrees C, The simple empirical expression K = K-0(1 - alpha X + beta X(2)) is used to correlate the solubilization equilibrium constant (K) with the mole fraction of TCE in the micelles (X) at each temperature. The solubilization equilibrium constant has a maximum value at approximately 30 degrees C, the temperature at which the solubility of TCE in water is a minimum. Activity coefficients are also reported for TCE in the micelle; these values increase slightly with increasing mole fraction of TCE. The general solubilization behavior of TCE in CPC micelles resembles that of benzene or toluene in CPC, suggesting that TCE solubilizes in ionic micelles both within the hydrocarbon micellar interior and near the micellar surface. The values of ct for TCE are much smaller than those for phenol and phenol derivatives, indicating that TCE is not as tightly anchored in the head group region of the CPC micelles as are more polar solutes such as phenol and chlorinated phenols. With increasing temperature, the tendency of TCE to solubilize within the hydrocarbon core region of the micelles increases, relative to its tendency to solubilize in the micellar surface region.