Prediction and Experimental Measurement of Refractive Index in Ternary Hydrocarbon Mixtures

The physical properties of hydrocarbon mixtures are of great importance in the field of science and technology. Knowing the refractive index of multicomponent liquid mixtures is essential in order to characterize these systems; however, there is a limited amount of experimental data regarding their optical properties. The present study provides precise experimental measurements of the refractive indices of three hydrocarbon compounds: 1,2,3,4-tetrahydronaphthalene (THN), isobutylbenzene (IBB), and dodecane (nC(12)). Sixty-three compositions (36 ternaries +27 binaries) were prepared and investigated along with their three pure components using a wide range of concentrations, temperatures and wavelengths. The refractive indices were measured using the multiwavelength Abbemat refractometer. The experimental data were then used to develop and validate new mathematical correlations which can be used to predict the refractive index of ternary mixtures as a function of concentration, temperature, and wavelength. There was a strong correlation between the experimental data and the predictive values with average residual values of +/- 1.55.10(-3). This study also investigated the relative validity of the experimental measurements of the refractive indices with theoretically estimated values using mixing rules and data from the literature. The experimental values were in substantial agreement with the predictive equation values with deviations of +/- 2.50.10(-3).