Titanium Dioxide Mediated Photocatalysed Degradation of Phenoxyacetic Acid and 2, 4, 5-Trichlorophenoxyacetic Acid, In Aqueous Suspensions (original) (raw)

2007, Journal of Molecular …

The photocatalytic degradation of maleic hydrazide (1), propham (2), tebuthiuron (3), propachlor (4), chlortoluron (5), thiram (6), phenoxyacetic acid (7), 2,4,5-trichlorophenoxy acetic acid (8), 4-chlorophenoxy acetic acid (9), uracil (10), 5-bromouracil (11) and bromothymol blue (12) have been investigated in aqueous suspensions of titanium dioxide (TiO 2) under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics of the compounds were investigated under different conditions, such as types of TiO 2 , pH, catalyst concentration, substrate concentration, temperature and in the presence of different electron acceptors, such as hydrogen peroxide (H 2 O 2), potassium persulphate (K 2 S 2 O 8), ammonium persulphate (NH 4) 2 S 2 O 8 and potassium bromate (KBrO 3) besides molecular oxygen. TiO 2 Degussa P25 was found to be more efficient photocatalyst for the degradation of the model compounds as compared with other photocatalysts. The degradation products were analysed using GC/MS analysis technique and probable pathways for the formation of different products have been proposed.