Evaluation of Fe(iii)EDTA reduction with ascorbic acid in a wet denitrification system

The reduction of Fe(iii)EDTA to Fe(ii)EDTA is the core process in a wet flue gas system with simultaneous desulfurization and denitrification. Herein, at first, the reductant ascorbic acid (VC) was used for reducing Fe(iii)EDTA. The feasibility of Fe(iii)EDTA reduction with ascorbic acid was investigated at different Fe(iii)EDTA concentrations, various pH values, diverse temperatures, and different molar ratios of VC to Fe(iii)EDTA. The results showed that the Fe(ii)EDTA concentration increased with an increase in the initial Fe(iii)EDTA concentration. Furthermore, the reduction efficiency increased as the mole ratio of VC to Fe(iii)EDTA was increased, and all the Fe(iii)EDTA reduction efficiencies were close to 100% when the mole ratio was more than 0.5. On the other hand, an alkaline environment did not favor the conversion of Fe(iii)EDTA by VC. The Fe(iii)EDTA conversion slightly increased as the temperature was increased. Moreover, compared with other reduction systems, ascorbic acid (VC) was found to be more powerful in reducing Fe(iii)EDTA, especially in air. In addition, VC only exhibited powerful ability in the conversion of Fe(iii)EDTA to Fe(ii)EDTA and hardly reduced Fe(ii)EDTA–NO. Finally, the stoichiometry of Fe(iii)EDTA reduction by ascorbic acid was derived. Thus, our study would offer a bridge between foundational research and industrial denitration using the combination of Fe(ii)EDTA and VC.