Oxidative degradation of organic pollutants utilizing molecular oxygen and visible light over a supported catalyst of Fe(bpy)32+ in water

This article explores a supported catalyst of Fe(bpy)32+ on a cationic exchange resin (Amberlite IRA 200) as a photocatalyst for the degradation of organic pollutants by activating molecular oxygen under visible irradiation (λ>420 nm) in water. Different from Fe(bpy)32+ which is not photoactive in solution, the supported catalyst exhibits a very efficient photoactivity for the degradation of N,N-dimethylaniline and the cationic dyes of Rhodamine B (RhB) and Malachite Green (MG) in an aerated aqueous medium. TOC removal yield was 75, 60 and 58%, respectively, after 700 min of visible light irradiation. The photocatalytic activity of the supported Fe(bpy)32+ remained unchanged after 22 cycles of over 100 h. The photocatalyst was characterized by UV-Vis diffuse reflectance, and X-ray photoelectron spectroscopies (XPS). EPR studies suggest that the active superoxide species {Fe(bpy)33+O2−} are involved in the light-activated reaction. A reaction mechanism is proposed in the text.