Water Desalination and Reuse Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Water Desalination and Reuse Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; Facultad del Mar y Medio Ambiente, Universidad del Pacifico, Guayaquil, Ecuador.
Water Res. 2014 Dec 1;66:140-148. doi: 10.1016/j.watres.2014.08.017. Epub 2014 Aug 27.
Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen ((1)O2), triplet state of DOM ((3)DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20 h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching.
根据产生单线态氧 ((1)O2)、溶解态有机 matter 的三重态 ((3)DOM*) 和羟基自由基 (·OH) 的性能，研究了不同溶解态有机 matter (DOM) 的光敏特性。辐照后 DOM 溶液的光漂白特性通过荧光激发-发射矩阵和紫外-可见光谱进行了表征。在阳光模拟器中改变了预辐照 DOM 溶液的光敏性能。研究了 DOMs 在几种污染物的光催化降解中的性能。在 20 h 的暴露时间内，一些污染物的观察降解速率常数 (kobs) 随暴露时间的增加而降低，且高度依赖于 DOM 和污染物的性质。kobs 较低的污染物的降解更容易受到 DOM 光漂白诱导的 kobs 降低的影响。在当前的实验条件下，DOM 在污染物降解中光反应性的光漂白诱导降低主要归因于光诱导 DOM 部分与光化学产生的活性物质之间的相互作用引起的 DOM 间接光转化。反应性污染物可以通过清除活性物质来抑制 DOM 的间接光漂白，因此这些污染物的光催化降解表现出稳定的 kobs。这是首次报道 DOM 光漂白诱导的污染物同时光催化降解中 DOM 变化以及反应性污染物对 DOM 光漂白的抑制作用的研究。
