Mass transfer study on the electrochemical removal of copper ions from synthetic effluents using reticulated vitreous carbon

Abstract

Porous electrodes have been successfully used for metal electrodeposition from diluted aqueous solution due to their high porosity and specific surface area, which lead to high mass transfer rates. This work studies the mass transfer of copper electrodeposition on reticulated vitreous carbon in a flow reactor without membrane. The flow configuration, otherwise the filter-press electrochemical reactors, was designed in order to minimize the pressure drop. The mass transfer coefficient was determined by voltammetric and galvanostatic electrodeposition. In the voltammetric experiments a Luggin capillary was used to measure the current–potential curves and to determine the limiting current (and, consequently, the mass transfer coefficient). In the galvanostatic experiments the concentration–time curves were obtained and considering a limiting current kinetics model, the mass transfer coefficient (k _m) was determined for different flow velocities. The results showed that both methods give similar values of k _m, thus the voltammetric method can be recommended because it is faster and simpler. Finally, the reactor performance was compared with others from literature, and it was observed that the proposed reactor design has high Sherwood numbers similar to other reactor configurations using membranes and reticulated vitreous carbon electrodes.

Keywords:

• mass transfer coefficient
• reticulated vitreous carbon
• electrodeposition
• heavy metals
• electrochemical treatment

Acknowledgements

The financial support from FAPESP and CAPES is acknowledged. P.H. Britto-Costa thanks CNPq for the scholarship. The help of Lúcia Mascaro during the RDE experiments is gratefully acknowledged.