Photodegradation of chlortoluron sensitised by iron(III) aquacomplexes

The degradation of chlortoluron photoinduced by Fe(III) aquacomplexes has been investigated under continuous irradiation at 365 nm. The determined quantum yields of chlortoluron disappearance give evidence for the involvement of the most photoactive species Fe(OH)2+, which leads to the formation of hydroxyl radicals and Fe(II); the importance of oxygen in the degradation process was also demonstrated. According to the nature of the obtained photoproducts, the attack of OH radicals on two sites of chlortoluron are favoured: the aromatic ring and the methyl group of the urea function. A homogenous photocatalytic process based on the oxidation of Fe(II) into Fe(III) is responsible for the continuous production of hydroxyl radicals in such a system. This photocatalytic cycle allows the total mineralisation of compounds like chlortoluron using conditions compatible with a safe aquatic environment.