Effects of chloride and sulfate on the rate of oxidation of ferrous ion by H2O2

The rates of oxidation of Fe(II) by H2O2 in the presence of sodium perchlorate, sodium nitrate, sodium chloride and sodium sulfate salts (0–1 M) have been compared in the study. Experiments were carried out in a batch reactor, in the dark, at pH <3, 25±0.5°C and at controlled ionic strength ( 1 M). The experimental results showed that the rates of oxidation of Fe(II) in the presence of chloride, nitrate and perchlorate were identical. In the presence of sulfate, the rate of oxidation of Fe(II) was faster and depended on the pH and the concentration of sulfate. The pseudo second-order rate constants for the reaction of H2O2 with Fe2+, FeCl+ and FeSO4 were determined as 55±1, 55±1 and 78±3 M−1 s−1, respectively.