TRANSIENT ANALYSIS OF ACTIVE DISSOLUTION OF IRON BY USING CHANNEL FLOW DOUBLE ELECTRODE

The active dissolution mechanism of iron in sulfuric acid solution has been investigated by the transient analysis with a channel flow double electrode (CFDE) system. The transient current after potential step is separated into partial electrochemical steps, which are Fe(II) dissolution and surface accumulation, using fast Fourier transformation (FFT) analysis with the dynamic collection efficiency, N(omega). The Fe(II) dissolution follows the formation of the adsorbed intermediate in the active dissolution potential region. The experimental results suggest the existence of two adsorbed species during the active dissolution of iron. The formation efficiency of adsorbed intermediate on the iron surface, phi(i)(omega), and the dissolution efficiency of ferrous ions, phi(diss)(omega), are calculated from the transient currents. The amplitude of phi(diss)(omega) decreases and that of phi(f)(omega) increases with the frequency. The numerical simulations for the active dissolution of iron have been performed on the basis of the reaction model involving two kinds of adsorbed species, and the elemental reaction rates have been estimated.