Kinetic studies on the extraction of citric acid from aqueous solutions with tri-n-octylamine

In this paper, the rates of the extraction of citric acid from aqueous solutions with tri-n-octylamine dissolved in xylene were measured using a stirred membrane-based cell in the 298–328 K temperarature range. It was found that, under the conditions studied, both forward extraction and back-extraction processes were mainly controlled by chemical reactions occurring at the interface on the organic side. The intrinsic rate constants for the formation and dissociation of the acid complexes were determined and a possible reaction mechanism was proposed. The effect of temperature on the reaction kinetics was also investigated and the activation energies were thus obtained.