A factorial-design study of the variables affecting the electrochemical reduction of Cr(VI) at polyaniline-modified electrodes

An electrochemical process using reticulated vitreous carbon-supported polyaniline cathodes is proposed to reduce toxic hexavalent chromium, which is present in industrial wastewater. The effect of five variables was simultaneously studied: (1) flow velocity; (2) current density; (3) electrode thickness; (4) electrode porosity and (5) Cr(VI) concentration. Due to the number of variables, a Box-Behnken factorial-design was chosen in order to reduce the number of experiments required. The current efficiency, energy consumption and space-time yield were the variables evaluated. The process was also analyzed in terms of the polymer stability and the overpotential distribution inside the porous electrode. (c) 2005 Elsevier B.V. All rights reserved.