Interfacial Kinetics of the Stripping of Acetic and Citric Acids from Tri-n-octylamine Complexes

Abstract

A rotating diffusion cell (RDC) was used to measure the kinetics of acetic and citric acids stripping from an organic solvent phase to water. It has been proved that the carboxylic acid transfer is rate controlled by a diffusion process. The rate constant for acetic acid was found to be (3.43 ± 0.18) × 10⁻⁵ m·s⁻¹ at 298 ± 0.1 K. For citric acid, the rate constant determined as a function of temperature was k = (0.043 ± 0.002)e ^−3680/T for which the activation energy is 30.6 ± 1.0 kJ-mol⁻¹. The stripping resistance depends on the number of carboxylic acid groups in the acid and is largely entropic in nature.