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New Mechanistic Insights into the Transformation of Reactive Oxidizing Species in an Ultraviolet/Sulfite System under Aerobic Conditions: Modeling and the Impact of Mn(II)
ACS ES&T Water Pub Date : 2021-07-23 , DOI: 10.1021/acsestwater.1c00110
Dandan Rao 1 , Hongyu Dong 1 , Lushi Lian 2 , Yuankui Sun 1, 2 , Xin Zhang 3 , Lei Dong 3 , Gongming Zhou 1, 2 , Xiaohong Guan 1, 2
Affiliation  

Sulfite [S(IV)] photolyzed with 254 nm ultraviolet (UV) light was used as a surrogate for S(IV)-based advanced oxidation processes (AOPs) to elaborate the S(IV) chain transformation process, which plays a pivotal role in S(IV)-based AOPs but is poorly understood. The level of degradation of ibuprofen in the UV/S(IV) system increased with an increase in the initiation rate of S(IV) chain transformation, and SO4•– was the major oxidant. Trace Mn(II) in the UV/S(IV) process promoted ibuprofen degradation, S(IV) transformation, and peroxymonosulfate production at pH 6.0–8.0 but inhibited these processes at pH 9.0. A mathematic model (model 1) was constructed for the UV/S(IV) system, and it revealed that 40% of dosed S(IV) was transformed to SO4•– but ∼95% of the generated SO4•– was reduced by S(IV), resulting in the low oxidation capacity of the UV/S(IV) system. Upon incorporation of the reactions related to Mn(II)/Mn(III) transformation into model 1, model 2 was built to simulate the transformation kinetics of S(IV), ibuprofen, and peroxymonosulfate in the UV/Mn(II)/S(IV) system, which demonstrated that Mn(III) tended to oxidize S(IV) and worked as a chain carrier at pH 6.0–8.0 but was apt to disproportionate and acted as a chain terminator at pH 9.0. These results will guide the efforts to optimize the performance of S(IV)-based AOPs.

中文翻译:

对有氧条件下紫外线/亚硫酸盐系统中反应性氧化物质转化的新机理见解:建模和 Mn(II) 的影响

用 254 nm 紫外 (UV) 光光解亚硫酸盐 [S(IV)] 作为基于 S(IV) 的高级氧化过程 (AOP) 的替代物来阐述 S(IV) 链转化过程,这起关键作用在基于 S(IV) 的 AOP 中,但知之甚少。UV/S(IV)体系中布洛芬的降解水平随着S(IV)链转化引发速率的增加而增加,SO 4 •–是主要的氧化剂。UV/S(IV) 过程中的痕量 Mn(II) 在 pH 6.0–8.0 时促进了布洛芬降解、S(IV) 转化和过氧单硫酸盐的产生,但在 pH 9.0 时会抑制这些过程。为 UV/S(IV) 系统构建了一个数学模型(模型 1),结果表明 40% 的剂量 S(IV) 转化为 SO 4 •–但约 95% 的生成 SO 4 •–被 S(IV) 还原,导致 UV/S(IV) 系统的氧化能力低。将与 Mn(II)/Mn(III) 转化相关的反应纳入模型 1,建立模型 2 以模拟 S(IV)、布洛芬和过氧单硫酸盐在 UV/Mn(II)/S 中的转化动力学(IV) 系统,表明 Mn(III) 倾向于氧化 S(IV) 并在 pH 值 6.0-8.0 下用作链载体,但在 pH 值 9.0 时易于歧化并充当链终止剂。这些结果将指导优化基于 S(IV) 的 AOP 性能的努力。
更新日期:2021-08-13
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