DISTRIBUTION OF OXALIC-ACID BETWEEN WATER AND ORGANIC SOLUTIONS OF TRI-N-OCTYLAMINE

The extraction of oxalic acid from an aqueous solution into solutions of tri-n-octylamine in single solvents toluene, chloroform, and methyl isobutyl ketone was investigated. In addition to batch extraction exp eriments and isopiestic measurements in the binary system oxalic acid/ water, infrared spectroscopic measurements were performed. These spect roscopic investigations yield information about the stoichiometry of c omplex formation. All measurements were carried out at 298.15 K. A mod el for the liquid-liquid equilibrium is presented which was used to co rrelate the experimental data. The model takes into account chemical r eactions as well as physical interactions in both phases. Many of the model parameters could be deduced from information about subsystems us ing also the new isopiestic measurements. However, as several complexe s of oxalic acid and tri-n-octylamine with as well as without water ha ve to be considered, some model parameters had to be adjusted using ex perimental data from batch extraction experiments. The model reliably describes the partitioning of all components onto the coexisting phase s.