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.