Heterogeneous photocatalytic decolorization and degradation of structurally related textile reactive dyes in aqueous suspension of ZnO nanotube

Nanotube of ZnO was prepared using hydrothermal process and its hexagonal nanocrystal structure was determined using scanning electron microscopy and X-ray diffraction. The nanoparticles had the wurtzite hexagonal crystal structure and showed good adhesion to the nanotubes. The nanosized ZnO displayed high photocatalytical activity toward decolorization of C.I. Reactive Yellow 84 (RY 84) and Reactive Orange 12 (RO 12) under concentrated solar irradiation. The effects of various parameters such as amount of catalyst, pH, and concentration of dye on photodecolorization were systematically investigated. The optimum photocatalyst dose was found to 200 mg/L, optimal pH was 4 of 100 mg/L aqueous solution of the dyes. Almost 100% color removal was achieved in about 6 h, the process simultaneously reduces chemical oxygen demand, which obeyed pseudo first-order kinetics. © 2010 American Institute of Chemical Engineers Environ Prog, 2010