Isobaric Vapor–Liquid Equilibrium for the Butyl Acetate + Ethyl Lactate Binary System at 101.3, 80.0, 60.0, and 40.0 kPa

Vapor–liquid equilibrium (VLE) is crucial for the design of waste photoresists and solvent recycling processes. Isobaric VLE data for the butyl acetate + ethyl lactate binary system were experimentally determined using a modified Othmer still at pressures of 101.3, 80.0, 60.0, and 40.0 kPa. The thermodynamic consistency of experimental VLE data was rigorously validated using Fredenslund’s test and Van Ness’s point-to-point test. The data were then correlated to the Wilson, NRTL, and UNIQUAC models. The results demonstrate that the three local composition models provide an excellent fit to the experimental data, significantly outperforming the predictive UNIFAC model. The thermodynamic consistency of the regressed binary interaction parameters was further confirmed through a graphical analysis of the Gibbs energy of mixing. These findings are essential for the accurate design and simulation of distillation processes and facilitate the development of sustainable solvent recovery technologies for the semiconductor industry.