Abstract:
In this study, various types of photocatalysts were synthesized viz., ZnO, CeO2, ZnO/CeO2, via precipitation method and MWCNTs/ZnO, MWCNTs/ZnO/CeO2 and zeolite supported MWCNTs/ZnO/CeO2 were prepared by impregination method. Crystal structure, band gap energy and optical properties of each of the photocatalysts were characterized by modern techniques using XRD, Uv-vis and PL instruments, respectively. Photocatalytic activities of all the supported and unsupported nanocomoposites were evaluated using methylene blue as a model organic pollutant dye solution as well as on a real sewage sample solution collected from Bahir Dar textile industry. Zeolite supported MWCNTs/ZnO/CeO2 photocatalyst exhibited effective degradation efficiency of methylene blue (MB) dye than bare T3 (at 125 mg MWCNTs/ ZnO/CeO2) nanocomposite was found to be 93.71 % and 83.21 % respectively under visible light irradiation, significantly lower than the supported mixed oxide indicating that zeolite plays significant role in the performance of the composite that increasing adsorption capacity. The effects of pH, initial dye concentration, PZC, catalyst load as well as mechanism of scavenger reaction were investigated using photocatalyst nanocomoposite of T3 (at 125 mg MWCNTs/ZnO/CeO2). The Mechanism of scavenger reactions also assures that the most important species in the degradation process would be •O2- and •OH. The Stability towards photocatalytic degradation of the Zeolite supported MWCNTs/ZnO/CeO2 was evaluated only about 20.8% decrement was observed after four successive runs that can confirm that supported nanocomoposite has good stability. Supported photocatalyst also exhibited a relatively higher efficiency on the photodegradation of MB than real sewage sample solutions which is about 94.11 and 76.74%, respectively. Photocatalytic degradation of MB dye follows the pseudo first order kinetics for the as-synthesized nanocomposite.
