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.