Preparation, Characterization and Photocatalytic Application of Tio2 Supported on Zeolites for Textile Wastewater Treatment
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Date
2016-04-04
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Addis Ababa University
Abstract
In this PhD research, potential of Ethiopian natural zeolite for photocatalytic application has been assessed and 10, 20, 40 wt% TiO2 supported on selected synthetic zeolite materials have been systematically prepared. Different treatment conditions both on the zeolite surface and TiO2 have been attempted. Selected zeolites were treated at different conditions to make their surface chemistry suitable for TiO2 support. The properties of supported TiO2 were also tuned by changing the synthesis conditions. Furthermore, metal and nonmetal co-doped TiO2 supported on zeolites have been prepared.
The prepared samples were characterized by X-ray diffraction (XRD), elemental analysis (ICP-OES), Thermogravimetric Analysis (TGA), N2 adsorption-desorption isotherms, UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), Scanning Electron Microscopy (SEM/EDS), Scanning Transmission Electron Microscopy with High Angular Annular Dark Field detector (STEM/HAADF), Electron Energy Loss Spectroscopy (STEM/EELS), Photoluminescence (PL) Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Crystalline TiO2 with particle sizes ranging from 6 nm to 9 nm and semi- amorphous TiO2 were prepared supported on zeolites. The supported TiO2 showed higher light absorption coefficient and lower photoluminescence emissions than the pristine TiO2 nanoparticles. iv
Photocatalytic activity of the samples was tested for the degradation of MO, a stable and non biodegradable azo dye. The reusability of the photocatalysts prepared and leaching extent of Ti4+ species during the photocatalytic reaction have been determined for selected samples. Photocatalytic treatment of real wastewaters from a textile factory in Ethiopia has been tested using selected synthetic photocatalysts.
The supported TiO2 nanoparticles showed higher photocatalytic activity than the pristine TiO2 nanoparticles. The enhanced photocatalytic activity of the supported TiO2 system is attributed to the dual role of the zeolite on enhancing adsorption capacity of the composite and brought some electronic changes on the TiO2 to lower photogenerated electron hole recombination rate. Leaching prevention and reusability are the added values of the zeolites in the photocatalytic reaction tested. Furthermore, the photocatalytic activity of the semi-amorphous TiO2 brings new features of TiO2 based photocatalysis, which needs further investigations.
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Keywords
Preparation, Characterization, Photocatalytic, Application of Tio2 Supported, Zeolites for Textile, Wastewater Treatment