Sonochemical Oxidation of Acid Blue 113 by Fe (II)-activated Hydrogen Peroxide and Persulfate in Aqueous Environments

Residual Azo dyes pose a major environment problem due to the benzene rings present in their structure. In this experimental study, the efficiencies of the US/H2O2/Fe2 and US/S2O82‒/Fe2 processes in degrading Acid Blue 113 Azo were investigated. For this purpose, the effects of the parameters involved in these processes such as initial solution pH in the range of 3 to 11, different concentrations of H2O2, and ‒S2O82 in the range of 1 to 10 mM, those of FeSO4 in the range of 0.1 to 1 mM, and different initial dye concenterations were investigated in a batch ultrasound reactor operated at 40 kHz. Also, the effects of aeration on process efficiency and fluctuations in the dye UV-Vis spectrum were investigated under optimum conditions. Based on the results obtained, dye removal efficiency decreased considerably in both processes with increasing pH such that maximum removal efficiency was obtained at pH 3 in both processes. Similarly dye removal efficiency decreased in both processes when FeSO4 concentration rose above 0.5 mM. The optimum conditions in the US/H2O2/Fe2 process to achieve a removal efficiency of 93.5% for an initial dye concentration of 50 mg/L involved H2O2 and FeSO4 concentrations of 2.5 and 0.05 mM, respectively. Under the same optimal conditions, the efficiency of the US/S2O82‒/Fe2 process was found to be 94.3% for a S2O82‒ concentration of 2.5 nM. These results suggest that the US/S2O82‒/Fe2 is more effective than the US/H2O2/Fe2 in reducing the 567 nm peak of the dye structure. Finally, examination of the changes in the UV-Vis spectra of Acid Blue 113 showed that the US/H2O2/Fe2 process led to greater declines in the 276 and 203 nm peaks.