AQUATIC PHOTOCHEMISTRY OF CHLORINATED TRICLOSAN DERIVATIVES: POTENTIAL SOURCE OF POLYCHLORODIBENZO-P-DIOXINS
AQUATIC PHOTOCHEMISTRY OF CHLORINATED TRICLOSAN DERIVATIVES: POTENTIAL SOURCE OF POLYCHLORODIBENZO-P-DIOXINS
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DOI：
10.1897/08-490.1
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发表时间：
2009-12-01
影响因子：
4.1
通讯作者：
Arnold, William A.
中科院分区：
文献类型：
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作者：
Buth, Jeffrey M.;Grandbois, Matthew;Arnold, William A.
三氯生（TCS; 5-氯-2-（2，4-二氯苯氧基）苯酚）是一种常见的抗微生物剂，在输送到废水处理厂或废水氯消毒过程中，可能与自来水中的余氯发生反应，生成氯化TCS衍生物（CTD）：4，5-二氯-2-（2，4-二氯苯氧基）苯酚（4-Cl-TCS）、5，6-二氯-2-（2，4-二氯苯氧基）苯酚（6-Cl-TCS）和4，5，6-三氯-2-（2，4-二氯苯氧基）苯酚（4，6-Cl-TCS）。由于可能形成多氯二苯并对二恶英（PCDD）光产物，研究了CTD的光化学。光解率是高度依赖于CTD形态，因为酚类物质降解速度比苯酚形式的44至586倍。对于酚盐物质，TCS、4-Cl-TCS、6-Cl-TCS和4，6-Cl-TCS的光解量子产率值分别为0.39、0.07、0.29和0.05。在密西西比河和约瑟芬湖（美国）的沃茨进行的光解得到类似的量子产率缓冲，纯水在相同的pH值，表明间接光解过程涉及光敏溶解的有机物是没有竞争力的直接光解。在自然和缓冲纯水中，三种CTD在太阳照射下转化为PCDDs的光化学转化率为0.5%至2.5%。CTD衍生的PCDDs具有更高的毒性比2，8-二氯二苯并-p-二恶英，一个以前确定的TCS的光产物，由于其较高的氯取代在侧位。据估计，美国地表沃茨中的TCS和CTD衍生的多氯二苯并对二恶英的含量为每年46至92克毒性当量单位。其他确定的光产物的每一个CTD是2，4-二氯苯酚和还原脱氯产物。
Triclosan (TCS; 5-chloro-2-(2,4-dichlorophenoxy)phenol), a common antimicrobial agent, may react with residual chlorine in tap water during transport to wastewater treatment plants or during chlorine disinfection of wastewater, generating chlorinated TCS derivatives (CTDs): 4,5-dichloro-2-(2,4-dichlorophenoxy) phenol (4-Cl-TCS), 5,6-dichloro-2-(2,4-dichlorophenoxy) phenol (6-Cl-TCS), and 4,5,6-trichloro-2-(2,4-dichlorophenoxy) phenol (4,6-Cl-TCS). The photochemistry of CTDs was investigated due to the potential formation of polychlorodibenzo-p-dioxin (PCDD) photoproducts. Photolysis rates were highly dependent upon CTD speciation, because the phenolate species degraded 44 to 586 times faster than the phenol forms. Photolysis quantum yield values for TCS, 4-Cl-TCS, 6-Cl-TCS, and 4,6-Cl-TCS of 0.39, 0.07, 0.29, and 0.05, respectively, were determined for the phenolate species. Photolyses performed in Mississippi River and Lake Josephine (USA) waters gave similar quantum yields as buffered, pure water at the same pH, indicating that indirect photolysis processes involving photosensitization of dissolved organic matter are not competitive with direct photolysis. The photochemical conversion of the three CTDs to PCDDs under solar irradiation was confirmed in natural and buffered, pure water at yields of 0.5 to 2.5%. The CTD-derived PCDDs possess higher toxicities than 2,8-dichlorodibenzo-p-dioxin, a previously identified photoproduct of TCS, due to their higher chlorine substitution in the lateral positions. The load of TCS- and CTD-derived PCDDs to United States surface waters is estimated to be between 46 and 92 g toxicity equivalent units per year. Other identified photoproducts of each CTD were 2,4-dichlorophenol and reductive dechlorination products.