Photo-oxidation of o-chloroaniline in the presence of TiO2 and IO3 -: A study of photo-intermediates and successive IO3 - dose

The photocatalytic oxidation in TiO2and IO3-has been found to be an effective process to degrade the aromatic organic pollutant, o-chloroaniline (o-ClA). The degradation of o-ClA is mainly attributed to the {radical dot}OH attack. Several organic intermediates were identified and the existence of aromatic intermediates would not accumulate in the solution as their degradations were observed. A relatively high level of iodoaniline was solely owing to the use of IO3-which could experience further decay under UV/TiO2condition. Further investigation on second IO3-dose has indicated a faster o-ClA degradation, but the degree of degradation depends on the time interval between each dose. It is observed that the disappearance of o-ClA and intermediates was the fastest when shorter interval of second IO3-dose (i.e., 5 min). Slower degradation at longer IO3-interval (i.e., 20 min) is possibly due to consumption of radicals from first dose and the inhibition of iodide, the eventual reduction product of IO3-. With the inclusion of the photo-products, the degradation pathway of o-ClA has been proposed accordingly.