ZnO-mediated solar photocatalytic degradation of azo dye

Abstract

Wastewaters generated from the textile industry contain large amounts of azo dyes which, owning to their non-biodegradability, toxicity and potential carcinogenic nature, constitute a major threat to the surrounding ecosystem. Environmental concerns and the need of meeting the stringent international standards for rejecting wastewaters has made the development of novel, efficient and low cost methods for the purification of textile aqueous effluents an issues of major importance. ZnO-mediated solar photocatalytic has been shown to be a potentially advantageous process as it may lead to complete mineralization at ambient conditions with the use of solar light as the energy sources. In the present study, the photocatalytic degradation of a model textile azo dye (Acid Orange 7, AO7) in aqueous solution is investigated with the use of ZnO photocatalyst. The effect of various parameters such as catalyst loading (0.5 g/L – 2.5 g/L), initial dye concentration (50 – 200 mg/L), and color removal on the degradation of dye has been studied. The reaction pathway of dye degradation was also investigated by monitoring the final product in solution, with the use of a technique including UV-Vis spectrophotometer. Catalyst loading affects decolourization efficiency of Acid Orange 7 which is maximized at about 2.5 g/L catalyst loading where colour removal was 99.8% while for effect of initial dye concentration which is 50 mg/L, the colour removal was 92%.