Photo-Fenton degradation of malachite green catalyzed by aromatic compounds under visible light irradiation

The photo-Fenton degradation of malachite green (MG) catalyzed by aromatic derivatives under visible light irradiation was examined. Aromatic derivatives exhibit significant catalytic action in the photo-Fenton reaction. The degradation rates of MG with various kinds of aromatic derivatives obey the following order: hydroquinone > salicylic acid > quinone > carboxylic aromatic derivatives > amido aromatic derivatives. GC-MS detection of the products formed in the MG Fenton degradation in the presence of aromatic derivatives shows that the addition of the latter does not change the MG degradation pathways, although it greatly alters the reaction rate. The MG degradation mainly involves two different pathways: cleavage with a [MG–OH]˙ transition intermediate and N-demethylation.