Oxidation of sulfite is an important process in wet flue gas desulfurization. The non-catalyzed intrinsic oxidation kinetics of sulfite was experimentally studied in an intermittent apparatus, showing that the oxidation reaction proceeded with two steps, one rapid reaction in rich oxygen zone and the other slow reaction in poor oxygen zone. In the rich oxygen zone, the reaction is 1.0 order for sulfite and 1.0 order for dissolved oxygen, and the activation energy is 49.3 kJ•mol^－1. In the poor oxygen zone, the reaction is 2.0 order for sulfite and zero order for dissolved oxygen, and the activation energy is 122.6 kJ•mol^－1. The reaction mechanism was hypothesized, which is in good agreement with the experimental results.

Key words: desulfurization, sulfite, non-catalyzed oxidation, intrinsic reaction, kinetics