Prediction of salt effect on vapor-liquid equilibrium in ethanol-water system by scaled particle theory

The salt effect parameters(from Furter's equation) of three electrolytes (NaCl, NaBr, KCI) for various ethanol-water mixtures were determined by vapor-liquid equilibrium experiments. A calculation method of this parameter(K) by the scaled particle theory was suggested. The term of hard sphere interactions was calculated by using Masterton-Lee's equation, and that of soft sphere interactions was treated by using Y. Hu's radial distribution function method, i.e. taking the first coordination shell as in order, and out of the shell as random mixing. The interactions between the charge of ions and dipole or induced dipole of the central molecule were considered effectively within the limits of the first coordination shell, and the ions out of the shell were regarded as L-J molecules. In this paper a correlation equation for the located dielectrical constant and liquid concentration was proposed and the predicted results of the salt effect parameters were in agreement with the experiments by this equation.