Effect and Transformation Rule of Br-in UV/H2O2 Process on Acetaminophen Removal
Br-is a common halogen ion in water and wastewater,and it plays various roles in advanced oxidation processes(AOPs)through forming different kinds of Br-related species.In the presence of Br-,acetaminophen(AAP)simulated wastewater was used to study its degradation efficiency,mechanism,and Br-transformation rule in UV/H2O2 process.The results showed that the best removal rate of 99.1％was achieved during the degradation of AAP by UV/H2O2.But the addition of Br-inhibited the degradation and mineralization of AAP and O·2 and OH· were the main reactive substances in the UV/H2O2 degradation of the simulated AAP wastewater containing Br-,with contributions of 45.5％and 34.0％,respectively.When Br-was present,the fastest AAP degradation rate was achieved under neutral conditions with a primary kinetic constant of 0.0484 min-1,and the contribution rate of reactive bromine species(RBSs)to AAP degradation was 14.1％.Radical concentration simulations indicated that Br·-2 may played an important role in the formation of organic bromine.The direct reduction by H2O2 resulted in a Br-transformation of only 18.0％.In addition,due to the addition of bromine radicals,some ecotoxic by-products were easily generated,and the degradation pathways of AAP were inferred by analyzing the bromine substitution products.
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