Experimental and Modeling Study on Mixing Properties of Ternary System Methyl tert-Butyl Ether + n-Hexane + Cyclohexane at 298.15 K

This paper is a combined experimental and modeling study aimed at exploring the densities, sound speeds, and refractive indices of the ternary system MTBE + n-hexane + cyclohexane and its binary subsystems at a temperature of 298.15 K under ambient pressure conditions. Experimental data were used to derive essential properties such as excess molar volumes, excess isentropic compressibilities, and refractive index deviations. The excess and deviation properties provided invaluable insights into the interactions occurring among the mixture components. Redlich–Kister and Cibulka's equations were employed to correlate these properties for binary and ternary systems, respectively. Remarkably, the standard deviations consistently fell below the estimated uncertainties associated with the corresponding properties, attesting to the robustness of the correlations. Additionally, the Perturbed Chain Statistical Associating Fluid Theory was applied to model the density of both binary and ternary mixtures. The study also compared Schaaff’s collision factor theory and Nomoto’s relation in their ability to predict sound speeds for the investigated mixtures. Various mixing rules, including Lorentz-Lorenz, Gladstone-Dale, Laplace, and Eykman, were employed to model the refractive indices of the mixtures. The efficacy of these models in predicting the properties was evaluated using the average absolute percentage deviation between the experimental and calculated values. The modeled densities matched well with the experimental data, with overall deviations of 0.19 %, 0.38 %, and 0.25 % for the binary systems MTBE + n-hexane, MTBE + cyclohexane, and n-hexane + cyclohexane, respectively, and 0.21 % for the ternary system MTBE + n-hexane + cyclohexane. Notably, Nomoto’s relation exhibited superior performance in predicting both binary (overall deviation of 0.65 %) and ternary (deviation of 1.10 %) sound speeds. In contrast, any of the four tested mixing rules performed equally well for predicting binary and ternary refractive indices. This work contributes to the understanding of interactions between components in mixtures. It also provides valuable data for petrochemical and environmental engineers involved in designing extraction processes, processing equipment, and formulating gasoline blends that meet the industry's rigorous standards and align with environmental sustainability goals.