Kinetics of the [Fe(III)-EDTA]- Reduction by Sulfite under the Catalysis of Activated Carbon

The simultaneous removal of SO2 and NO from the flue gases with the [Fe(II)-EDTA](2-) solution has not been put into commercial application because of the quick oxidation of [Fe(II)-EDTA](2-) to [Fe(III)-EDTA](-). Activate carbon has been proposed to catalyze the reduction of [Fe(III)-EDTA](-) by the sulfite produced from the dissolution of SO2. In this paper, the kinetics of [Fe(III)-EDTA](-) reduction catalyzed by coconut activated carbon has been investigated in a stirred-cell reactor. The experimental results indicate that the activated carbon can obviously accelerate the [Fe(III)-EDTA](-) reduction rate. The reaction rate increases with the concentrations of [Fe(III)-EDTA](-) and sulfite. An optimal pH for the reduction of [Fe(III)-EDTA](-) is obtained at 6.34. Raising the temperature can increase the [Fe(III)-EDTA](-) conversion. The intrinsic activation energy for this catalytic reaction obtained is 55.63 +/- 1.12 kJ mol(-1). The experiments manifest that a high NO removal efficiency can be maintained for a long period of time with the [Fe(II)-EDTA](2-) solution coupled with the Fe(II) regeneration catalyzed by activated carbon. A kinetic equation describing the reduction of [Fe(III)-EDTA](-) by sulfite catalyzed with activated carbon was developed.