Diffusion of Benzyl Acetate, 2-Phenylethyl Acetate, 3-Phenylpropyl Acetate, and Dibenzyl Ether in Mixtures of Carbon Dioxide and Ethanol

Abstract

Diffusion coefficients of four solutes at infinite dilution (benzyl acetate, 2-phenylethyl acetate, 3-phenylpropyl acetate, and dibenzyl ether) were measured in the system CO2 + ethanol from 313.16 to 333.16 K and pressures between 15 and 35 MPa over the full concentration range of the CO2 + ethanol mixture. The diffusional behavior in the mixed solvent was compared with the estimation of seven simple predictive equations, Le Blanc, Wilke−Chang, Holmes−Olander−Wilke, Tang−Himmelblau (two formulas), Perkins−Geankoplis, and Leffler−Cullinam, observing that the first two give errors between 17 and 30% and that deviations lower than 11% are only obtained with the expressions of Tang−Himmelblau. Nevertheless, as none of the studied equations considers the self-association of ethanol nor complex formation between solute and alcohol molecules, the model of Lusis−Ratcliff and Mohan−Srnivasan was extended to a ternary liquid−supercritical system with the diffusing component dilute, obtaining average absolute deviations lower than 4.6% for the diffusivities of the four solutes. Nevertheless, the extension of this model is correlative (it needs one adjustable parameter for each solute), not predictive.