where k ¼ 0.0637mM1 h1. As shown in Fig. 1, only a small
improvement in the rate and extent of COD reduction
occurred on increasing the H2O2 dosage from 10 to 15 mM.
This was attributed to the scavenging of OH by excess H2O2
(Yonar et al., 2006), where the higher concentration of H2O2
photolyses to produce more OH which in turn reacts with
H2O2 to form the less reactive O2H, thus decreasing the rate of
COD reduction.