Effect of complexation on photocatalytic degradation of dissolved organic nitrogen compounds

Abstract

The effect of metal ions on TiO2 mediated photocatalytic oxidation for the determination of dissolved organic nitrogen compounds is investigated. Ethylenediaminetetraaceticacid was chosen as a model molecule for DON compounds. At pH 2, 5, 7, and 10 aqueous EDTA solutions were irradiated at 254 nm in the presence of Fe2+, Cu2+, Zn2+, Ni2+ or Co2+ ions. The sum of produced nitrate, nitrite, and ammonium ion concentrations gave the total oxidation recovery. At low pH, the photocatalytic oxidation recoveries of Fe-EDTA, Ni-EDTA, and Co-EDTA were significantly lower than the photocatalytic degradation of EDTA. The presence of free Fe2+, Ni2+, and Co2+ ions decreased the photocatalytic oxidation recovery. The [NH4+]/[NO3-] ratio was higher for Cu-EDTA.