Photocatalysed degradation of a herbicide derivative, maleic hydrazide in aqueous suspensions of TiO2

The photocatalytic degradation of a herbicide derivative maleic hydrazide [1,2-dihydro-3,6-pyridazinedione, 1], has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic technique and depletion in Total Organic Carbon (TOC) content as a function of irradiation time. The degradation kinetics were investigated under different conditions such as different types of TiO2, pH, catalyst concentration, substrate concentration and in the presence of electron acceptors such as hydrogen peroxide (H2O2) and potassium bromate (KBrO3) besides molecular oxygen. Semiconductor Degussa P25 was found to be more efficient as compared with other photocatalysts.