Examination of photocatalytic redox process in removal of bisphenol-A in wastewater

The visible light-active nitrogen-doped TiO2 photocatalyst had been synthesized in the Environmental Laboratory by wet chemistry method in which the TiCl4 as the Titanium source and NH4OH as the nitrogen precursor with mole ratio of 1:10. The sample was calcinated in tube furnace at 400oC and 600oC for 2 hours with a constant flow of nitrogen gas. Pale yellowish catalyst powders were obtained from both calcinations temperature, indicating N-doped TiO2. Characterization was performed on both the lab synthesized N-doped photocatalyst (N-TiO2-400 and N-TiO2-600) by XRD, UV-Vis DRS, BET, FTIR and SEM-EDX. P25 was used to illustrate the characteristic of undoped TiO2 semiconductor photocatalyst during the characterization process. From the XRD results, both N-TiO2 samples obtained 100% anatase phase. It was also observed that the particle size and the surface area of the photocatalyst is strong influence by the calcinations temperature. At higher calcination temperature, smaller particle size and larger surface area can will be formed. The results from FTIR and EDX indicated both N-TiO2 catalyst attain a typical characteristic of TiO2 photocatalyst. Nitrogen bonding in the catalyst is not significant in the FTIR results but UV-VIS-DRS results indicated a significant absorption tail at range around (400 – 550nm) for both N-TiO2-400 and N-TiO2-600. Both catalysts were examined for their photocatalytic decomposition of BPA at 5ppm under the UV (368nm) and visible light (> 400nm) irradiation. Different catalyst loading (0.1, 0.2, 0.5g/l) were used in the photocatalytic decomposition under UV. Both catalysts were also evaluated for their photocatalytic decomposition of BPA at 5ppm under visible light with catalyst loading of 0.5g/l. From the PCO experiment under UV, it was found that the photocatalytic reaction rate increases with the loading of catalyst. At 0.5g/l, N-TiO2-400 and N-TiO2-600 achieved over 90% degradation within 3 hours. Photocatalytic decomposition under visible light, the degradation of BPA is much less significant. The degradation efficiency is around 15 – 25% within 3 hours.Bachelor of Engineering (Environmental Engineering