Production of Photo-oxidants by Dissolved Organic Matter During UV Water Treatment

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• 作者：Yaal Lester ; Charles M. Sharpless ; Hadas Mamane ; Karl G. Linden
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：October 15, 2013
• 年：2013
• 卷：47
• 期：20
• 页码：11726-11733
• 全文大小：331K
• 年卷期：v.47,no.20(October 15, 2013)
• ISSN：1520-5851

文摘

Dissolved organic matter (DOM) irradiated by sunlight generates photo-oxidants that can accelerate organic contaminant degradation in surface waters. However, the significance of this process to contaminant removal during engineered UV water treatment has not been demonstrated, partly due to a lack of suitable methods in the deep UV range. This work expands methods previously established to detect ¹O₂, HO鈥? H₂O₂, and DOM triplet states (³DOM*) at solar wavelengths to irradiation at 254 nm, typical of UV water treatment. For transient intermediates, the methods include a photostable probe combined with selective scavengers. Quantum yields for ¹O₂, ³DOM* and H₂O₂ were in the same range as for solar-driven reactions but were an order of magnitude higher for HO鈥? which other experiments indicate is due to H₂O₂ reduction. With the quantum yields, the degradation of metoxuron was successfully predicted in a DOM solution irradiated at 254 nm. Further modeling showed that the contribution of DOM sensitization to organic contaminant removal during UV treatment should be significant only at high UV fluence, characteristic of advanced oxidation processes. Of the reactive species studied, ³DOM* is predicted to have the greatest general influence on UV degradation of contaminants.