LAUSR

The isothermal vapor–liquid equilibrium (VLE) data for a binary system of 4-nonyl phenol diethoxylate with sec-butanol at (333.0 to 425.0) K have been measured by using a static-type apparatus. The system pressures at a given feed composition were measured to generate the P–T–x data and are further compared to the pressure values calculated using the Antoine equation. Two thermodynamic models, the UNIQUAC and the NRTL models, were selected to correlate the VLE data at various temperatures. The analysis showed that the experimental data agree well with these activity coefficient models. Finally, the solvent activities were estimated, and the values are consistent with the values calculated from the phase equilibrium data.