Oxidation rate in the preparation of polyferric sulfate coagulant

The oxidation rate of ferrous sulfate was investigated in the preparation of polyferric sulfate(PFS) coagulant. It was proved that this reaction is zero order with respect to Fe 2+ , first order with respect to NO\-2(g) and first order with respect to the interface area between gas phase and liquid phase. If the partial pressure of NO\-2(g) in gas phase is increased or the interface area is increased, the time needed to complete the reaction will be decreased.