Kinetic Consideration of Photochemical Formation and Decay of Superoxide Radical in Dissolved Organic Matter Solutions
Kinetic Consideration of Photochemical Formation and Decay of Superoxide Radical in Dissolved Organic Matter Solutions
复制标题
溶解有机物溶液中超氧自由基光化学形成和衰变的动力学考虑
DOI：
10.1021/acs.est.9b06018
复制
发表时间：
2020-03-17
影响因子：
11.4
通讯作者：
Song, Weihua
中科院分区：
文献类型：
--
作者：
Ma, Jianzhong;Nie, JianXin;Song, Weihua
用荧光法直接测定了辐照溶解性有机物（DOM）溶液中超氧自由基离子（O-2）的光化学生成和衰减速率。在光照条件下，未催化和催化的O-2（中心点-）歧化约占空气饱和DOM溶液中O-2（中心点-）总降解量的25%。观察到光诱导的O-2（中心点）损失，其不产生H2 O2。O（2）（中心点-）的光化学形成和光诱导损失速率均与DOM的供电子能力呈正相关，表明酚类基团在O（2）（中心点-）的光化学行为中起着双重作用。在空气饱和条件下，12种DOM溶液的O-2（中心点-）量子产率在1.8 ~ 3.3%c范围内变化，平均值为（2.4 ± 0.5）%c. O（2）（中心点-）的量子产率随溶解氧浓度的增加而非线性增加。因此，单电子还原中间体（O-2（中心点-）的前体）的量子产率计算为（5.0 +/- 0.4）%c。高能三线态（（DOM）-D-3*，E-T > 200 kJ mol（-1））和O-1（2）猝灭实验表明，3DOM * 和O-1（2）在O-2（中心点-）产生中起次要作用。这些结果对预测阳光照射下表层沃茨中O-2（中心点-）的光化学生成和衰减是有用的。
The photochemical formation and decay rates of superoxide radical ions (O-2(center dot-)) in irradiated dissolved organic matter (DOM) solutions were directly determined by the chemiluminescent method. Under irradiation, uncatalyzed and catalyzed O-2(center dot-) dismutation account for similar to 25% of the total O-2(center dot-) degradation in air-saturated DOM solutions. Light-induced O-2(center dot-) loss, which does not produce H2O2, was observed. Both the O(2)(center dot-)photochemical formation and light-induced loss rates are positively correlated with the electron-donating capacities of the DOM, suggesting that phenolic moieties play a dual role in the photochemical behavior of O-2(center dot-). In air-saturated conditions, the O-2(center dot-) quantum yields of 12 DOM solutions varied in a narrow range, from 1.8 to 3.3%c, and the average was (2.4 +/- 0.5)%c. The quantum yield of O(2)(center dot- )nonlinearly increased with increasing dissolved oxygen concentration. Therefore, the quantum yield of one-electron reducing intermediates, the precursor of O-2(center dot-), was calculated as (5.0 +/- 0.4)%c. High-energy triplets ((DOM)-D-3*, E-T > 200 kJ mol(-1)) and O-1(2) quenching experiments indicate that 3 DOM* and O-1(2) play minor roles in O-2(center dot-) production. These results are useful for predicting the photochemical formation and decay of O-2(center dot-) in sunlit surface waters.