The electrochemical reduction of Cr(VI) ions in acid solution at titanium and graphite electrodes

Cyclic voltammetry (CV) and rotating disc electrode (RDE) linear sweep voltammetry were used to study the reduction of Cr(VI) ions on a titanium electrode at 298 K. Diffusion controlled reduction of Cr(VI) ions occurred between -0.22 V and -0.45 V vs. Ag/AgCl and appears to take place in a single, 3-electron step. The diffusion coefficient was 1.2 × 10-5 cm2 s-1, which agrees with data reported in the literature. Following a study in a three-electrode cell, the electrolysis of 2 × 10-3 mol dm-3 Cr(VI) in 0.1 mol dm-3 H2SO4 solution at -1.0 V vs. Ag/AgCl, on titanium and -0.65 V vs. Ag/AgCl on carbon electrodes were carried out. The area of the electrodes was 64 cm2 and the mean linear flow velocity of electrolyte past the cathode varied between 10 and 80 cm s-1 (630-5680 cm3 min-1). The parasitic reactions of oxygen reduction and hydrogen evolution, which decreased the current efficiency, were observed during the reduction of Cr(VI) ions at titanium electrodes. © 2016 Elsevier Ltd. All rights reserved.

Diffusion coefficient; Graphite; Hexavalent chromium; Titanium Carbon; Chromium compounds; Cyclic voltammetry; Diffusion; Electrodes; Electrolytes; Electrolytic reduction; Flow velocity; Graphite; Graphite electrodes; Ions; Reduction; Titanium; Diffusion controlled; Electrochemical reductions; Hexavalent chromium; Linear flow velocities; Linear sweep voltammetry; Rotating disc electrode; Three electrode cells; Titanium electrodes; Electrochemical electrodes

VIVO