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A study on the reduction of [Fe(III)-EDTA] catalyzed with activated carbon in a fixed-bed

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The simultaneous control of SO2/NOX can be realized with the [Fe(II)-EDTA]2− aqueous solution. However, the [Fe(II)-EDTA]2− is easily oxidized to [Fe(III)-EDTA] by oxygen, which has no ability to bind NO. The reduction of [Fe(III)-EDTA] to [Fe(II)-EDTA]2− is a key to the maintenance of the NO removal efficiency with the [Fe(II)-EDTA]2− aqueous solution. The reduction of [Fe(III)-EDTA] can be accomplished by sulfite produced by SO2 dissolving in the aqueous solution under the catalysis of activated carbon. The experiments were performed in a fixed-bed reactor to investigate the regeneration of [Fe(II)-EDTA]2− catalyzed by activated carbon. The influences of [Fe(III)-EDTA] and sulfite concentrations, pH, liquid flow, temperature, on [Fe(III)-EDTA] catalytic reduction have been tested. The experimental results indicate that the [Fe(III)-EDTA] reduction increases with the [Fe(III)-EDTA] and sulfite concentrations. Raising the temperature can increase the [Fe(III)-EDTA] conversion. The optimal pH range for the reduction of [Fe(III)-EDTA] is 5.7–7.5. The apparent activation energy determined from the experimental results is 35.2 ± 0.5 kJ mol−1. The continuous experiment manifests that simultaneous removal of NO and SO2 with the [Fe(II)-EDTA]2− solution coupled with the Fe(II) regeneration catalyzed by activated carbon can be maintained at a high NO removal efficiency for a long period of time. The kinetic equation of [Fe(III)-EDTA]- reduction by sulfite catalyzed with activated carbon can be described as

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© 2012 American Institute of Chemical Engineers Environ Prog, 32: 206-212, 2013