Photo-catalyzed p-nitrophenol degradation in aqueous dispersions of ferrihydrite and H2O2.

Abstract

Nitrophenols are hazardous and toxic to living organisms. For this study, ferrihydrite was prepared to test its capabilities for p-nitrophenol degradation. A ferrihydrite particle prepared in neutral environmental conditions is sphere-like with a diameter of 2-4 nm and its total surface area is approximately 229 m2 x g(-1). The combination of ferrihydrite and trace H2O2 is effective for the degradation of p-nitrophenol under simulated sunlight irradiation. Hydroquinone, the initial intermediate of p-nitrophenol decomposition, autocatalyses the subsequent degradation of p-nitrophenol because it accelerates the photo-reductive dissolution of ferrihydrite. The effect of key operating parameters such as ferrihydrite dosage, initial solution pH and H2O2 dosage were also studied on the photocatalytic degradation of p-nitrophenol. The results indicate that the combination of 0.2 g x L(-1) ferrihydrite, 0.45 mmol x L(-1) H2O2 is highly efficient for the degradation of p-nitrophenol (0.15 mmol x L(-1)) at pH 2.5-3.0. A ferrihydrite was reused several times, still keeping its original photocatalysis.