Liquid–Liquid Equilibria of the Ternary Systems Undecane + 1,4-Diethylbenzene + Tetrahydrothiophene 1,1-Dioxide and Tridecane + 1,4-Diethylbenzene + Tetrahydrothiophene 1,1-Dioxide at T = (323.15, 348.15, and 373.15) K

Equilibrium tie-line data have been determined at 323.15 K, 348.15 K, and 373.15 K for the liquid–liquid equilibria (LLE) of the ternary systems undecane + 1,4-diethylbenzene + tetrahydrothiophene 1,1-dioxide and tridecane + 1,4-diethylbenzene + tetrahydrothiophene 1,1-dioxide. The relative mutual solubility of 1,4-diethylbenzene is higher in undecane + tetrahydrothiophene 1,1-dioxide than in tridecane + tetrahydrothiophene 1,1-dioxide mixture. The tie-line data were correlated with the universal quasichemical (UNIQUAC) and nonrandom two-liquid (NRTL) models. The calculated values based on the UNIQUAC model were found to be better than those based on the NRTL model; the average root-mean-square deviation between the phase composition obtained from the experiment and that from the calculation was 0.3788 for UNIQUAC compared to 0.4459 for NRTL. The values of selectivity and distribution coefficients were derived from the equilibrium data.