LAUSR

Abstract Photocatalytic degradation of three dyes, aniline blue (AB), brilliant green (BG) and direct red 80 (DR 80) by transition metal oxide nanocomposites having p-p isotype heterojunction, NiO/CuO and p-n type heterojunction, CuO/ZnO and ZnO/NiO has been explored under sun light and UV light. The effect of reaction conditions such as initial dye concentration, catalyst dosage, pH, contact time and presence of electron acceptor on photocatalytic degradation of these dyes was investigated. A suitable mechanism has been proposed for the photocatalytic degradation of dyes by the nanocomposites with illustration. The results show that NiO/CuO has higher degradation ability on AB dye (91 %) than BG (82 %) and DR 80 dyes (67 %). Among the three nanocomposites, the enhanced degradation ability shown by NiO/CuO are due to its lowest particle size, reduced electron/hole pair recombination, high BET surface area and increased OH radical generation during the photocatalytic reaction. The percentage degradation of all the dyes was carried out under sun light and UV light. It has been found that the rate of dye degradation under sun light is slightly higher than in UV light due to the existence of all type of radiations in sun light.