Liquid−Liquid Equilibria in Binary Mixtures of Water with Malonitrile, Succinonitrile, and Glutaronitrile

Liquid−liquid equilibria of binary mixtures of water and dinitrile solvents malononitrile, succinonitrile, and glutraronitrile have been studied in temperature range of 15 to 70 °C. The phase diagrams show that the critical mole fraction and consolate temperature (°C) (x c, T c) are (0.25, 58) for malononitrile and (0.19, 56) and (0.12, 68) for succinonitrile and glutraronitrile, respectively. The nonrandom two-liquid (NRTL) equation has been used to correlate of the activity coefficients of the components in binary mixtures. The parameters needed for the calculation are the energy parameters (g 12 − g 22) and (g 21 − g 11) and the nonrandom parameter α, which are determined by solving the NRTL equation with the aid of a nonlinear least-squares curve-fitting program. From the parameters of this equation, the excess Gibbs energies, G E, were calculated. Good agreement between the experimental data of phase diagrams and model results was achieved.