Asulam in Aqueous Solutions: Fate and Removal Under Solar Irradiation

The photodegradation of the pesticide asulam (methyl(4-aminophenyl)sulfonyl]carbamate) in aqueous solutions (1.0 2 10 m 4 mol L m 1 = 23 mg L m 1 ) has been investigated with and without Fe(III). The asulam disappearance were measured by direct photolysis at 254 nm as a function of pH and oxygen concentration. Different photoproducts have been identified, among them a blue condensation product which was only observed upon selective direct excitation of asulam. In the presence of Fe(III) and by excitation at 365 nm, we obtained the complete mineralisation of asulam, while no complete transformation of organic carbons into CO 2 was observed by direct photolysis. The continuous formation of ” OH radicals generated from the excitation of Fe(III) species allowed the total mineralisation of asulam. Information is also given about the fate of asulam in aqueous solutions under solar irradiation.