Synergistic effect of ozone on cadmium doped zinc oxide nanocatalyst for the degradation of textile dyeing wastewater

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Degradation of textile dyeing wastewater by nano Photocatalytic Ozonation and the synergistic effect of ozone on nanocatalyst is reported in the present study. Cadmium doped Zinc oxide (Cd–ZnO) nanocatalyst was synthesized by wet chemical method and used for the photocatalytic ozonation (PCO) process. Prepared catalyst was characterized by x-ray Diffraction (XRD), Field Emission Scanning Microscopy (FESEM) and Energy dispersive x-ray (EDAX). Degradation studies were performed in an annular photoreactor after optimizing the reaction influencing factors such as Ozone dose, pH and Cd–ZnO dosage. COD removal was 83% with 0.2 mg l −1 of the Cd–ZnO, 0.48 g h −1 of ozone at pH 7. Synergistic effect of ozone on Cd–ZnO was proved from the study of kinetics of integrated and individual processes. Integrated process (Cd–ZnO/UV/O 3 ) showed 4.2 and 3.5 times increased rate compared to Cd–ZnO/UV and O 3 . Biodegradability of the treated wastewater was found to increase from 0.08 to 0.42 after nano PCO. Results support the integration of nano PCO with biological treatment for the degradation of textile dyeing wastewater as a cost effective route.