Photocatalytic reaction by Fe(III)–citrate complex and its effect on the photodegradation of atrazine in aqueous solution

The photodegradation of atrazine in aqueous solutions containing citrate and Fe(III) was studied under Xe lamp irradiation on a time scale of hours. It was found that the presence of Fe(III)–citrate complex enhanced the photodegradation rate of atrazine as a result of OH attack. Atrazine photodegradation followed first-order reaction kinetics and the rate depended upon pH and light intensity. High citrate concentrations led to increased photodegradation of atrazine due to the fact that citrate not only acted as a carboxylate ligand but also a reductant of Fe(III). The interaction of Fe(III) with citrate was characterized using UV–visible absorption and Fourier-transform infrared (FTIR) spectroscopy, indicating that the hydrogen ions on the carboxyl groups were exchanged for Fe(III) ions. On the basis of these results, a reaction scheme was proposed in which the cycling of iron and carbon, the depletion of citrate and O2, and the formation of reactive oxygen species (ROS) were involved.