Simultaneous removal of SO2 and NO by FeII(EDTA) solution: promotion of Mn powder and mechanism of reduction

The effect of Mn powder addition on the simultaneous removal of SO2 and NO coupled with Fe-II(EDTA) absorption was investigated in this work. In the NO absorption system with Fe-II(EDTA), SO2 reduced Fe-II(EDTA)-NO to Fe-II(EDTA) with a reduction efficiency reaching 88.5% under the conditions of 4000 mg/m(3) SO2, pH 8.0, 44 degrees C, and the flow rate of 1.2 L/min within 60 min. Introducing 0.1 M Mn powder with SO2 increased the Fe-II(EDTA)-NO reduction efficiency to 96.8% within 5 min. SO2 was also removed by reducing Fe-II(EDTA)-NO and converted into SO42- at a removal efficiency of 100%. After adding Mn powder, NO was removed through the following reaction: 5Mn + 2Fe(II) (EDTA) - NO + 12H(+) -> 2Fe(II) (EDTA) + 5Mn(2+) + 2NH(4)(+) + 2H(2)O. Mn powder functioned as a reductant to regenerate the absorption of solution, and the coordinated NO in Fe-II(EDTA)-NO was reduced to NH4+. The resource utilization rate of N reached approximately 77.2%. The integrated technology is a potential solution for flue gas treatment in industrial sectors with coal-fired power plants and industrial boiler.