Isobaric phase equilibrium at local and sub-atmospheric pressures, molar refractivity, volumetric and viscometric properties of toluene (1) + para-tert-butyltoluene (2) at temperatures (293.15 to 308.15) K: Experimental studies and thermodynamic modeling

Abstract

para-tert-Butyltoluene is commercially produced by alkylation of toluene using isobutylene. The separation and purification of para-tert-butyltoluene are carried out by distillation. The absence of experimental data to design the separation equipment has resulted in the present study. The work presents experimental vapor-liquid equilibrium (VLE) studies of toluene (1) +para-tert-butyltoluene (2) binary system that were carried out in a modified Sweitoslawsky ebulliometer at sub-atmospheric pressures and local atmospheric pressure of 94.64kPa. The experimental VLE data were correlated with Wilson and NRTL activity-coefficient models. Regressed model parameters along with the deviations in bubble temperature have been presented. Moreover, experimental results of the refractive indices, densities and viscosities have been reported at different temperatures (293.15 to 308.15) K. Lorentz-Lorenz equation was employed for the estimation of molar refractivity (Rm). The measured data was used to calculate deviation in molar refractivity, ΔR, excess molar volume, VmE, deviation in viscosity, ∆η, and Excess Gibb's free energy of activation of viscous flow, ∆G⁎E. Results have been discussed in terms of interactions present among the mixing components. Excess partial molar properties at infinite dilution, V-i∞, were also investigated. Furthermore, a comparative study of different mixing rules for predicting refractive index was investigated and experimental viscosity data was correlated with different semi-empirical models.