Abstract:
Organic contaminants from industrial or domestic effluents may be harmful to humans
directly or indirectly by degrading the quality of environment. Consequently, these
contaminants must be reduced to levels that are not harmful to humans and the
environment before disposal. Chemical, physical and biological methods exist for the
removal of these pollutants from effluents. Among the available chemical methods,
heterogeneous photocatalytic oxidation has been found particularly effective in removing
a large number of persistent organics in water. In this dissertation, the synthesis of
Zn3V2O8 and metal chalcogenides for photocatalytic organic pollutant degradation is
reported. UV active photocatalyst Zn3V2O8 was synthesized by co-precipitation method.
However, it showed lower photocatalytic activity for dye degradation. In order to
increase the light absorption spectral range and photocatalytic activity of Zn3V2O8, its
heterostructures with metal chalcogenides (ZnSe and ZnTe) were synthesized. The
photodegradation activity of Zn3V2O8/ZnSe, for congo red dye was investigated and the
activity of Zn3V2O8/ZnTe will be determined in future. UV-Vis. photodegradation of dye
over Zn3V2O8-ZnSe heterostructures showed 84.3% congo red degradation, when 75% of
ZnSe was present in a composite. Bare ZnSe with both cubic and hexagonal phases
showed 89.4% of congo red degradation under UV-Vis. light. The as-synthesized
photocatalysts were characterized by different methods. Crystal structure, morphology,
purity, composition and band gaps of photocatalysts and their heterostructures were
studied by XRD, IR, SEM/EDX, and UV-Vis. DRS. Results for congo red degradation
clearly indicate the anomalous behavior of bare ZnSe that showed higher activity than
ZnSe heterostructure with Zn3V2O8.
