Mechanism of the initial stages of iron passivation in acidic sulfate solutions

Anodic and cathodic potentiostatic current transients of freshly formed iro n (99.95%) electrodes in 0.5 M aqueous acidic (pH 1.7-3.2) sulfate solution s are examined. The initial stages of iron passivation are confirmed to be determined by the following several processes each prevailing in a definite period: the formation of surface charge-transfer complexes (H2O)(ads)(delt a+) (first 3-5 ms) and their transformation into adsorbed OH- groups (subse quent 10-50 ms) with the concurrent adsorption of hydrogen atoms H-ads by i ron.