Degradation of Acid Blue 161 by Fenton and photo-Fenton processes

Degradation kinetics of azo dye, Acid Blue 161 (AB161), by Fenton and photo-Fenton processes in aqueous solution was investigated. At pH 3.5, the effects of H2O2, Fe2+, and H2O2/Fe2+ molar ratios, on the AB161 decolorization kinetic rates, were evaluated. Experimental results confirmed that the optimal H2O2/Fe2+ molar ratio of 12 is close to the theoretical value of 11 as predicted by previously developed model. The influence of azo bond loading (L (azo bond)), from 0.25 to 1.0, and pH values from 2.5 to 4.0 were evaluated on AB161 decolorization kinetic rates. A correlation between the natural logarithm of the decolorization rates and L (azo bond) was established at the different pH values. The decolorization rate increased linearly with decreasing L (azo bond), in the order of pH: 3.5 > 3.0 > 2.5 > 4.0. UV radiation of Fenton processes increases degradation of AB161 more than 40 % due to the regeneration of Fe2+ through photo-catalytic reactions. This phenomenon was confirmed by measuring H2O2 concentration during the photo-Fenton processes. The results suggest that Fenton processes can effectively decolorize or degrade wastewater containing azo dye, AB161. Photo-Fenton processes may further increase the degradation efficiency of AB161 by 40 %.