在UV/H_(2)O_(2)去除对乙酰氨基酚工艺中Br^(-)的影响及其转化规律

Effect and Transformation Rule of Br^(-)in UV/H_(2)O_(2) Process on Acetaminophen Removal

Br^(-)是水和废水中常见的卤素离子,在高级氧化过程(advanced oxidation processes, AOPs)中通过形成不同种类的Br相关物种来发挥多种作用。在Br^(-)存在条件下,采用对乙酰氨基酚(acetaminophen, AAP)模拟废水进行UV/H_(2)O_(2)对其降解效能、机理以及Br^(-)转化规律的研究。结果表明,UV/H_(2)O_(2)降解AAP过程中,最佳去除率达到99.1%,但Br^(-)的加入抑制了AAP的降解和矿化,O~·_(2)和OH~·是UV/H_(2)O_(2)降解含Br^(-)的AAP模拟废水中主要活性物质,贡献率分别为45.5%和34.0%。当Br^(-)存在时,中性条件下,AAP降解速率最快,其一级动力学常数为0.048 4 min~(-1);其中活性溴物种(reactive bromide species, RBSs)对AAP降解的贡献率为14.1%。自由基浓度模拟结果表明,Br^(·-)_(2)可能在有机溴的形成过程中发挥着重要的作用。H_(2)O_(2)的直接还原作用导致Br^(-)转化率仅为18.0%。此外,由于溴自由基的加成,容易生成一些具有生态毒性的副产物,并通过分析溴代产物推测了AAP的降解路径。

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/H_(2)O_(2) process.The results showed that the best removal rate of 99.1%was achieved during the degradation of AAP by UV/H_(2)O_(2).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/H_(2)O_(2) 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 H_(2)O_(2) 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.