Green Auxiliary Buffering Agent Effect on the Separation of Acetic Acid from Aqueous Solution: Phase Equilibrium Measurements and Modeling Study

Wastes produced by the biological oxidation of solid waste materials frequently contain diluted acetic acid solutions. Therefore, separating acetic acid from a mixture of several aqueous components remains difficult. In this study, the liquid–liquid extraction method was used to conduct an experimental separation of acetic acid from its aqueous solution using 1-heptanol as a solvent with the addition of biological buffer (HEPES/MOPS/EPPS) as a green auxiliary agent at 303.15 K and atmospheric pressure (0.1 MPa). The biological buffer was added in place of salt, which can boost the distribution coefficient and separation factor. The performance of acetic acid extraction using 1-heptanol as a solvent can be determined based on the distribution coefficient and separation factor. The buffering out strength sequence was MOPS > HEPES > EPPS, with separation factor and distribution coefficient values up to 507 and 14.1, respectively. The experimental results on liquid–liquid equilibrium for the 1-heptanol + acetic acid + water + biological buffer systems were found to be consistent using the Hand equation. Furthermore, the experimental data for liquid–liquid equilibrium can be well correlated by the NRTL and UNIQUAC models, with the RMSD values for both models in all systems of less than 1%.