The dependence of the decolorization efficiency of AR17 on the
initial concentration of H2O2 was tested by changing its
concentration from 0.5 mmol L1 to 5 mmol L1, while the other
operational conditions were held constant. Fig. 6 indicates that
when the H2O2 concentration increased from 0.5 mmol L1 to
1 mmol L1, the AR17 removal efficiency increased rapidly from
77% to 94.71%. This can be explained by the increase in the
formation of OH radicals which enhanced the removal efficiency
of AR17. However, by further increase of H2O2 concentration from
1 mmol L1 to 5 mmol L1, the AR17 removal efficiency gradually
decreased because of quenching of the produced OH radicals by
H2O2, described in the following equation