The objective of this research was to examine the heterogeneous catalytic decomposition of H 2 O 2 and 4-chlorophenol (4-CP) in the presence of activated carbons modified with chemical pretreatments. The decomposition of H 2 O 2 was suppressed significantly by the change of surface properties including the decreased pH pzc modified with oxidizing agent and the reduced active sites occupied by the adsorption of 4-CP. The apparent reaction rate of H 2 O 2 decomposition was dominated by the intrinsic reaction rates on the surface of activated carbon rather than the mass transfer rate of H 2 O 2 to the solid surface. By the detection of chloride ion in suspension, the reduction of 4-CP was not only attributed to the advanced adsorption but also the degradation of 4-CP. The catalytic activity toward 4-CP for the activated carbon followed the inverse sequence of the activity toward H 2 O 2 , suggesting that acidic surface functional group could retard the H 2 O 2 loss and reduce the effect of surface scavenging resulting in the increase of the 4-CP degradation efficiency. Few effective radicals were expected to react with 4-CP for the strong effect of surface scavenging, which could explain why the degradation rate of 4-CP observed in this study was so slow and the dechlorination efficiency was independent of the 4-CP concentration in aqueous phase. Results show that the combination of H 2 O 2 and granular activated carbon (GAC) did increase the total removal of 4-CP than that by single GAC adsorption.
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