Evaluation of Fe(II)EDTA-NO reduction by zinc powder in wet flue gas denitrification technology with Fe(II)EDTA

Abstract

Regeneration of Fe(II)EDTA, converting Fe(III)-EDTA and Fe(II)EDTA-NO to Fe(II)EDTA, is the key process in a wet flue gas denitrification technology with Fe(II)EDTA solution. In this paper, Zn powder was first employed as a reductant to reduce Fe(II)EDTA-NO. The stoichiometry and kinetics of Fe(II)EDTA-NO reduction by Zn powder were investigated with respect to Zn powder concentration, pH value, and temperature. The effect of the particle size of the Zn powder on Fe(II)EDTA-NO reduction was also investigated. The experimental results indicated that Fe(II)EDTA-NO reduction rate increased with the decrease of pH value and elevated temperature, and small particle size is beneficial to Fe(II)EDTA NO reduction. Fe(II)EDTA-NO reduction with Zn powder showed a pseudo-second-order reaction concerning Fe(II)EDTA-NO. In addition, the energy of activation (Ea) and the entropy of activation (ΔS‡) of the Fe(II)EDTA-NO reduction with Zn powder were estimated to be 19.853kJmol−1 and −135.557JK−1mol−1, respectively. Finally, the simultaneous reduction of Fe(III)EDTA and Fe(II)EDTA-NO with Zn powder was investigated. Results showed that Zn powder had better performance on simultaneous Fe(III)EDTA and Fe(II)EDTA-NO reduction as compared to the earlier related research. These fundamental researches can offer valuable guidance for industrial denitrification using mixed Fe(II)EDTA and Zn powder system.