Photocatalytic degradation of an organic pollutant by zinc oxide – solar process

Abstract

The photocatalytic degradation of 4-nitrophenol over irradiated ZnO suspensions was investigated in aerated aqueous solution. Complete degradation was achieved after irradiation with solar light, being the reaction rate dependent on the initial pH. The effect of various parameters such as catalyst loading, pH and initial concentration of 4-nitrophenol on degradation has been determined. The degradation was strongly enhanced in the presence of electron acceptors such as H2O2, K2S2O8 and KBrO3. The kinetics of heterogeneous photocatalytic degradation is discussed interms of Langmuir–Hinshelwood (L–H) kinetic model. The intermediates formed during the photodegradation were identified by GC–MS analysis. The mineralization of 4-nitrophenol has also been confirmed by COD measurements.