Electrooxidation of Cr³⁺ Ions in Sulfuric Acid Solutions

E. G. Vinokurov^a and V. V. Bondar’^b

^a Mendeleev University of Chemical Technology, Miusskaya pl. 9, Moscow, 125190 Russia

^b All-Russian Institute of Scientific and Technical Information, Russian Academy of Sciences, Moscow, Russia

Received March 2, 2006

Abstract — The effects the material nature of an anode, the cation radius and the metal–oxygen bond strength in the oxide anode on the rates of Cr³⁺ ion electrooxidation and the anode corrosion. A correlation between the rates of Cr³⁺ cation electrooxidation and corrosion of the anodes made of different metals is revealed. It is shown that the electrocatalytic activity of oxide anodes in the Cr³⁺ electrooxidation is caused by crystallographic and energy factors. The highest electrocatalytic activity is demonstrated by the oxides whose metal cat-ion radius exceeds that of dehydrated Cr³⁺ cation and the M–O bond energy is smaller than the bond energy in Cr₂O₃. The equation suggested takes simultaneously into account the effects of the oxide electrode cation radius and the mean energy of M–O bond on the relative rate of the Cr³⁺ ion electrooxidation.

PACS numbers: 82.45.Mk, 82.45.Qr