It is well-established that the pH is an important parameter
influencing the performance of the both homogeneous and
heterogeneous Fenton-like processes [29,30]. The effect of the
initial solution pH on heterogeneous Fenton-like removal of AR17
was analyzed over a pH range of 3 to 9 (Fig. 5). It can be seen that
the maximum amount of AR17 removal occurred at pH 3 to 5, and
then it slightly decreased with a further increase in the pH of the
solution. These results confirm that heterogeneous photo-Fentonlike
process can be implemented in a wide pH range. Thus it has the
advantage over the traditional homogenous Fenton-like process.
Moreover, at higher pHs, the process efficiency decreased swiftly
owing to the deactivation of catalyst by ferric hydroxide
precipitation [23]. Besides, hydroxyl radicals oxidation potential
in basic solutions is lower than acidic ones [4,31]. So, in order to
reach the maximum removal efficiency of AR17 further experiments
were implemented in pH of 3.