Photocatalytic elimination of aqueous 2-methyl-4- chlorophenoxyacetic acid in the presence of commercial and nitrogen-doped TiO2

An attempt to synthesize an active photocatalyst for 2-methyl-4-chlorophenoxyacetic acid removal has been accomplished. Black light (main emission wavelength at 365 nm) photocatalytic experiments with bare and N-doped titania have been carried out, and the results compared to those obtained in the presence of titania Degussa P-25. Doping percentage and calcination temperature influences have been investigated in photocatalytic runs using pure and commercial 2-methyl-4-chlorophenoxyacetic acid. In no case, the results obtained with synthesized titania improved the activity of P-25. Some kinetic tests allowed for the proposal of a pseudoempirical reaction mechanism capable of acceptably simulating the process in the presence of P-25. From the proposed mechanism, the roles played by hydroxyl, peroxyl and organic radicals have been suggested.