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首页> 外文期刊>Environmental Science & Technology >Transformation Kinetics of Phenols in Water: Photosensitization by Dissolved Natural Organic Material and Aromatic Ketones
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Transformation Kinetics of Phenols in Water: Photosensitization by Dissolved Natural Organic Material and Aromatic Ketones

机译：水中苯酚的转化动力学：溶解的天然有机物和芳香酮的光敏作用

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摘要

Different dissolved natural organic materials photosensitize the transformation of a series of methyl and methoxy phenols at pH 8 with a very similar high selectivity (reactivity range ≈ 50). This selectivity falls in the range of that achieved using the aromatic ketones benzophenone (BP), 3′-methoxyacetophenone (3′-MAP), and 2-acetonaphthone (2-AN) as model photosensitizers. For both natural and model sensitizers, the photooxidation at pH 8 is not controlled by singlet oxygen. Deuterium isotope effects (k_H/k_D) of different phenols are 0.7-1.3 for humic and fulvic acids and 1.1-1.7 for BP, suggesting an electron transfer mechanism. In contrast, the isotope effect for 2-AN of ≈ 4 indicates an H-atom abstraction reaction. The results show that reactive excited triplet states are important photooxidants in natural waters and should be considered for assessing the abiotic degradation of chemicals. The reactive triplet state concentration is estimated to be ≈ 10~(-14) M in the top meter of Lake Greifensee under summer noon sunlight, and this leads to a half-life of ≈ 7 h for 2,4,6-trimethylphenol. Further still uncharacterized photooxidants derived from the dissolved organic material are also involved in the phototransformation of the phenols.
机译：不同的溶解的天然有机材料在pH 8下以非常相似的高选择性（反应范围≈50）使一系列甲基和甲氧基苯酚的光敏化。该选择性落在使用芳族酮二苯甲酮（BP），3'-甲氧基苯乙酮（3'-MAP）和2-丙酮基萘酮（2-AN）作为模型光敏剂所达到的选择性范围内。对于天然和模型敏化剂，pH 8的光氧化均不受单线态氧的控制。不同酚类的氘同位素效应（k_H / k_D）对于腐殖酸和黄腐酸为0.7-1.3，对于BP为1.1-1.7，表明存在电子转移机制。相反，2-AN的同位素效应≈4表示H原子抽象反应。结果表明，反应性激发三重态在自然水中是重要的光氧化剂，应考虑用于评估化学物质的非生物降解。在夏季正午的阳光下，格里芬湖的最高米的反应性三重态浓度估计为≈10〜（-14）M，这导致2,4,6-三甲基苯酚的半衰期为≈7 h。仍然有衍生自溶解的有机材料的未表征的光氧化剂也参与酚的光转化。

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