激进的
光解
取代基
光降解
光化学
化学
脱质子化
氧气
动力学
戒指(化学)
辐照
降级(电信)
羟基自由基
反应机理
化学动力学
超氧化物
反应中间体
反应中间体
活性氧
反应速率常数
作者
H.Y. Li,Huiying Jia,Runze Fan,Wenjun Sun,Yanan Feng,Zifu Li,Xiuwei Ao
标识
DOI:10.1021/acs.est.5c13885
摘要
222 nm Far-UVC irradiation offers a promising mercury-free approach for removing sulfonamides (SAs) from water, but its photolytic mechanisms remain unclear. Here, the photodegradation of six representative SAs under 222 nm irradiation was investigated, emphasizing the roles of dissociated forms (neutral and deprotonated) and substituent structures (five-membered and six-membered heterocyclic). Results demonstrated that SAs' photodegradation proceeded through both direct photolysis and radical-mediated self-sensitized pathways. Dissociated forms primarily influenced the kinetics and the relative contributions of dual pathways: deprotonated forms (SAs0,-) generally degraded faster than their neutral forms (SAs+,-), and they are also more prone to attack by selectively photogenerated radicals. Substituent structures dictated bond-cleavage modes in direct photolysis: five-membered ring (5R) SAs underwent O-N or S-N cleavage, while six-membered ring (6R) SAs favored SO2 extrusion. In the self-sensitized pathway, hydroxyl radicals (•OH) and superoxide radicals (O2•-) were identified as the major reactive oxygen species (ROS), with •OH exhibiting a unique dual origin from both dissolved oxygen (DO) and H2O molecules. These findings provide mechanistic insights into 222 nm far-UVC-driven SAs degradation and inform the design of efficient, mercury-free UV-based water treatment systems.
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