Electrochemical incineration of oxalic acid: Reactivity and engineering parameters

Mass transfer measurements were carried out to test a disk-shaped parallel-plate electrochemical cell, based on a new design. The impinging-jet-cell concept, confined between parallel plates, was adapted to a configuration with one central inlet and several peripheral exit sections, leading to more effective hydrodynamics within the cell. Measurements of mass transfer coefficient were performed using the limiting diffusion current technique based on ferro-cyanide ion oxidation, and overall mass transfer coefficients were correlated to Reynolds numbers ranging from 30 to 200.  A comparison with literature on similar devices showed higher mass transfer coefficients can be obtained in the cell described in the present work. From the mass transfer standpoint, this type of cell could be a valuable tool in electrochemical wastewater treatment applications.  The electrochemical oxidation of oxalic acid was tested at different anode materials (Pb/PbO₂, boron-doped diamond, Ti/Pt and Ti/IrO₂–Ta₂O₅), showing that the new cell design enables limitations usually encountered with conventional batch cells to be overcome. However, the nature of the anode material remains an important parameter for the elimination of organic substrates.