Influence of aromatic additives on Bismarck Brown Y dye color removal treatment by Fenton processes.

The influence of diverse aromatic additives on Fenton processes (Fe2+/H2O2, Fe3+/H2O2) has been evaluated by using the Bismarck Brown Y (BBY) di azo dye as target pollutant. Results indicate that all tested Fe3+-reducing additives (gallic, 3,4-dihydroxyphenylacetic, 2,3-dihydroxybenzoic, and 2,5-dihydroxybenzoic acids, catechol, and hydroquinone) exhibited pro-oxidant properties during BBY dye color removal, mainly during Fe3+/H2O2 treatments. For example, in the presence of hydroquinone BBY color removal was increased from 22 to 83% for 60 min through the Fe3+/H2O2 process. The effect of non-reducing additives was less pronounced, among which salicylic and 2,4-dihydroxybenzoic acids were more efficient at removing dye color than benzoic acid and methylene blue. It was suggested that OH radicals may have converted non-reducing additives into Fe3+-reducing intermediates, which had a positive effect on the treatments. On the other hand, antioxidant properties were observed during BBY color removal in the presence of higher concentrations of gallic and salicylic acids. These items of data indicate that a minimum amount of aromatic additive was enough to increase BBY dye color removal by Fenton processes.