Electrochemical chromic acid regeneration process: fitting of membrane transport properties

A mathematical model was developed to predict changes in contaminant concentrations with time, and to estimate contaminant fluxes due to migration, diffusion, and convection in a laboratory-scale batch electrolysis cell for the regeneration of contaminated hard-chrome plating baths. The feed and extract compartments of the batch-cell were separated by a Nafion-117 diaphragm. The mathematical model was used to estimate process parameters and physical properties of Nafion-117 membrane from experimental results, assuming quasi-stationary operation. Best-fit ionic mobilities of Cu, Fe, and Ni through the Nafion-117 membrane were found to be 5.4, 1.7, and 5.2×10−10 cm2/V s, respectively.