Mechanism of anodic dissolution of iron in acetic acid solution

The catalytic mechanism of the spontaneous dissolution of iron was proved by combined electro- and radiochemical (ER) methods and by the measurement of the amount of the absorbed O2. Acidic solution (20%) of sodium acetate (pH=3.7) and Fe59 isotope produced by neutron irradiation were used to measure the corrosion rate of iron containing 0.005% carbon. The iron dissolves electrochemically as Fe→Fe2++2e, measured by the ER methods. The Fe3++e→Fe2+ reaction and the autocatalytic dissolution of iron were proved as well. The elementary steps of the chemical reaction: 4Fe2++O2+4H+→4Fe3++2H2O were experimentally verified. It has been demonstrated by both methods that the reduction of Fe3+ ions at the electrode as well as the oxidation of Fe2+ ions by chemical reaction are processes of high speed so they may cause high corrosion rate. (Sz.J.)