Chromic acid regeneration process with fuel cell electrode assistance. Part II: Electrochemical characterization, material compatibility and energy consumption

Electrochemical characteristics, energy consumption and material compatibility aspects of a novel process for regeneration of spent hard chromium plating baths using a Nafion-117 separator and a fuel cell cathode are discussed. Electrochemical impedance spectroscopy (EIS) and stationary polarization curves were used to characterize the performance of a fuel cell cathode in the regeneration cell. The configuration of the MEA, current collector, and flow distributing backing plate may, during long-term operation, lead to excessive ohmic resistance, which necessitates a special design of the cathode assembly. X-ray diffraction indicated that Cu, Fe, Ni, and Cr were deposited on the electrode matrix, leading to deactivation of the Pt-catalyst. The deactivation causes a rising cell voltage during electrolysis. Nevertheless, the energy consumption of the regeneration cell is at least 1 V less than that of a comparable cell with hydrogen evolving cathode.