HETEROGENEOUS AND HOMOGENEOUS WASTE-WATER TREATMENT COMPARISON BETWEEN PHOTODEGRADATION WITH TIO2 AND THE PHOTO-FENTON REACTION

The oxidative destruction of phenol, cyclohexanof (CyOH), and 4-nitroa niline (4-NA) in aqueous solution by the photo-Fenton reaction and TiO 2/UV-A is described and compared. The decomposition mechanisms were in vestigated by studying the intermediate products by HPLC and a photodi ode array. The degradation of 4-NA was monitored by GC/MS to trace the decomposition products (nitrobenzene, p-benzoquinone, hydroquinone an d resorcine). During the photochemical degradation of 4-NA nitrate ion s were detected by an ion selective electrode. The degradation rates w ith the photo-Fenton reaction had the following order: Phenol > 4-NA > > CyOH, in contrast to the order CyOH > Phenol > 4-NA obtained with Ti O2/UV-A. The same intermediate decomposition products were obtained fo r each substrate by both methods.