- Category: Volume 21 No.5 (September 2011)
Sustain. Environ. Res., 21(5), 299-305 (2011)
Brenda B. Zermeño, Edgar Moctezuma, and Ricardo García-Alamilla
Photocatalysis, phenol, ozone, titania
The photocatalytic degradation of phenol and 4-chlorophenol with TiO2 , oxygen or ozone and low energy UV light has been studied in order to identify the intermediate reaction products, elucidate the reaction mechanism and evaluate the kinetic reaction parameters. For this purpose, aqueous solutions of phenol or 4-chlorophenol are mixed with TiO2 and illuminated with low energy UV light to induce the photocatalytic oxidation reactions. Oxygen or ozone is bubbled through the reaction mixture. Samples are taken periodically to monitor the advance of the degradation and mineralization reactions by UV, high-performance liquid chromatography and total organic carbon analysis. The experimental results suggest that the degradation and mineralization reactions follow a pseudo first order reaction rate law and a pseudo-zero order reaction rate law, respectively. The results indicate that phenol is mineralized via benzoquinone and hydroquinone when oxygen is bubbled through the system. In the presence of ozone, phenol is also mineralized via catechol and benzenetriol. 4-chlorophenol is first transformed into phenol and hydroquinone. Then it follows the same reaction mechanism as phenol.