ENHANCED FLUE-GAS DENITRIFICATION USING FERROUS.EDTA AND A POLYPHENOLIC COMPOUND IN AN AQUEOUS SCRUBBER SYSTEM

Previous work in this laboratory has involved studying the possibility of combined NO(x)/SO2 scrubbing using various aqueous chemistries with a metal chelate additive. Rcently, we have focused our work on the metal chelate ferrous.EDTA [Fe(II).EDTA]. A problem encountered in the practical application of Fe(II).EDTA is that the ferrous ion has been found to oxidize to the corresponding ferric species, leading to a decrease in NO(x) removal for the scrubbing solution containing the additive. We have found that addition of a polyphenolic compound leads to a sustained high NO(x) removal under various oxidizing conditions. We believe that the improved performance of Fe(II).EDTA is due to the known capabilities of these organic compounds both to inhibit oxidation of ferrous chelates by dissolved oxygen and to rapidly reduce any ferric ions back to the original ferrous species. These effects are illustrated by the following chemical reactions: O2(1) + organic --> oxidized organic, and Fe(III) + organic --> Fe(II) + oxidized organic.