Effective Photocatalytic Degradation of Sunset Yellow by ZnO Nanophotocatalysts under Fluorescent Light Irradiation

The photocatalytic degradation of azo-based dye, sunset yellow using ZnO nanophotocatalysts was investigated under fluorescent light irradiation. The ZnO were investigated for crystallinity, grain size, surface area and optical properties. The effects of various operating parameters including initial dye concentration, photocatalyst amount and solution pH on the rate of degradation were investigated and optimized. The degradation followed pseudo first order kinetics. Under optimum conditions (8 mg/L sunset yellow concentration, 7.0 g/L ZnO amount and solution pH of 5.8), complete degradation of dye was achieved after 120 min irradiation and exhibited much higher photocatalytic activity than the commercial TiO2. The mineralization of the sunset yellow was confirmed by the total organic carbon measurements. In addition, the active species trapping experiments indicated that the hydroxyl radicals and superoxide anion radicals played pivotal role for the photodegradation of sunset yellow. The study clearly showed that fluorescent light photocatalysis over ZnO can be used as an effective tool for the treatment of dye contaminated water.