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 %.