Understanding the impacts of oxidant doses and dissolved organic carbon concentration on ozone and hydroxyl radical exposures in the peroxone process

This research investigates the effects of ozone (O3) and hydrogen peroxide (H2O2) doses, as well as the dissolved organic carbon (DOC) concentration, on O3 and hydroxyl radical (•OH) exposures (i.e., ∫[O3]dt and ∫[•OH]dt) during the peroxone (O3/H2O2) process. The addition of H2O2 during the ozonation process accelerated the O3 decomposition into •OH, increasing ∫[•OH]dt while decreasing ∫[O3]dt. The optimal [H2O2]/[O3] input ratio for maximizing ∫[•OH]dt was found to be around 0.2; at higher ratios, additional H2O2 consumption did not further increase ∫[•OH]dt. At higher DOC concentrations, both oxidant exposures decreased, and the effect of H2O2 on ∫[•OH]dt was diminished due to competitive reactions between H2O2 and DOC for O3, as well as scavenging of •OH by DOC. An increase in ∫[•OH]dt in the peroxone process exhibited a linear correlation with the [O3]/[DOC] ratio when the [H2O2]/[O3] input ratio was fixed at 0.2.