Experimental Measurements, Correlation, and Prediction Models to Study 1-Ethyl-3-methylimidazolium Tetrafluoroborate Ionic Liquid Ternary Mixtures

Volumetric and acoustic properties were obtained using density, rho(123), and speed of sound, u(123), experimental values for ternary systems of {[EMIM][BF4] (x(1)) + acetic acid (x(2)) + acetophenone (x(3))} (mix(1)) and {[EMIM][BF4] (x(1)) + propionic acid (x(2)) + acetophenone (x(3))} (mix(2)) at T = (293.15-333.15) K and 0.1 MPa. The observed V-m123(E) and Delta k(s)(123) data of the studied ternary mixtures were modeled with a total of 63 evaluated models, which resulted from a sum of each of nine predictive terms (no estimated parameters) with each of seven correlative terms (estimated parameters). The entire model is a correlative model, and if all of the parameters of the correlative term are set to zero, it becomes a predictive model. The ideal number of parameters in the correlation was then approximated using standard deviations (sigma). For mix(1), V-m123(E) was only negative and Delta k(s)(123) was only positive, while for mix(2) both negative and positive results were found for each property. Also, quantitative results point out that mix(1) is closer to ideal behavior than mix(2). The modeling for mix(2) employed more complex equations, with more parameters, and even so presented worse deviations than for mix(1). These results evidence the effect of one CH2 in the acid chain on the thermodynamic properties of these mixtures.