Kinetics and mechanism of photolysis and TiO2 photocatalysis of triclosan
Kinetics and mechanism of photolysis and TiO2 photocatalysis of triclosan
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DOI：
10.1016/j.jhazmat.2008.11.107
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发表时间：
2009-07-30
影响因子：
13.6
通讯作者：
Zoh, Kyung-Duk
中科院分区：
文献类型：
--
作者：
Son, Hyun-Seok;Ko, Gwangpyo;Zoh, Kyung-Duk
三氯生（5-氯-2-（2，4-二氯苯氧基）-苯酚），一种有效的广谱抗菌剂，降解进行了比较，在TiO 2-只有在黑暗条件下，光分解，和TiO 2与UV-A灯照射。与仅含TiO 2和光解条件相比，TiO 2可更有效地降解和矿化三氯生。而三氯生去除只有30%，在20分钟内，在光解和三氯生降解在同一时间分别为75%和82%，和TOC去除率显着高于在光解。动力学数据表明，三氯生在TiO 2上的吸附符合Langmuir吸附等温式，TiO 2吸附符合Langmuir-Hinshelwood吸附动力学模型（B = 27.99 mM（-1），K-三氯生= 9.49 mM（-1））。中性pH值有利于三氯生与TiO 2之间的电荷效应。添加2-丙醇，自由基清除剂，显着降低三氯生的光解和光解降解。在异丙醇存在和不存在的条件下，以及在异丙醇存在的条件下，二恶英类中间产物如二苯并二氯对二恶英（DCDD）、二苯并对二恶英（DCDD）在光解反应中均产生，而在异丙醇不存在的条件下，二恶英类中间产物均未被检测到。这一结果表明，三氯生的光催化降解主要是通过自由基来实现的，这些自由基一旦在光催化剂中产生，就可以进一步降解二恶英类中间体。(C)2008 Elsevier B. V.保留所有权利。
The degradations of triclosan(5-chloro-2-(2,4-dichlorophenoxy)-phenol), a potent broad-spectrum antimicrobial agent, were compared in TiO2-only in the dark condition, photolysis, and TiO2 photocatalysis with a UV-A lamp. TiO2 photocatalysis more effectively degraded and mineralized triclosan compared to TiO2-only and photolysis conditions. While triclosan removed only 30% by TiO2-only condition within 20 min, the triclosan degradation in photolysis and photocatalysis at the same time was 75 and 82%, respectively, and TOC removal was significantly higher in photocatalysis than in photolysis. The data of kinetics showed that triclosan adsorption onto TiO2 was fitted to Langmuir isotherm, and TiO2 photocatalysis was fitted to Langmuir-Hinshelwood model (b = 27.99 mM(-1),K-triclosan = 9.49 mM(-1)). The neutral range of pH was favorable to photocatalysis due to the charge effect between TiO2 and triclosan. The addition of 2-propanol, a radical scavenger, significantly reduced the degradation of triclosan both in photolysis and photocatalysis. Dioxin-type intermediates such as dibenzo-dichloro-p-dioxin (DCDD), dibenzo-p-dioxin were produced in photolysis with and without 2-propanol, and also in photocatalysis with 2-propanol, but these intermediates were not detected in photocatalysis without 2-propanol. This result indicates that the photocatalytic degradation of triclosan is mainly achieved by radicals, and these radicals can further degrade dioxin-type intermediates once they are produced in photocatalysis. (C) 2008 Elsevier B.V. All rights reserved.