Mechanism and kinetics of sulfamethoxazole photocatalytic ozonation in water
Mechanism and kinetics of sulfamethoxazole photocatalytic ozonation in water
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DOI：
10.1016/j.watres.2008.12.015
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发表时间：
2009-03-01
期刊：
影响因子：
12.8
通讯作者：
Garcia-Araya, Juan F.
中科院分区：
文献类型：
--
作者：
Beltran, Fernando J.;Aguinaco, Almudena;Garcia-Araya, Juan F.
在不同的实验条件下，研究了磺胺甲恶唑（SMT）在水中的光催化臭氧化作用。研究了气体流速、臭氧初始浓度、SMT 和 TiO(2) 的影响，以确定传质和化学反应的重要性。在所研究的条件下，该过程是化学控制的。 SMT 和 TOC 动力学均已考虑。分别观察到 SMT 和 TOC 氧化的臭氧反应的快速和慢速动力学状态。不同抑制剂的应用可以建立涉及直接臭氧化、直接光解、羟基自由基反应和光催化反应的反应机制。臭氧与质子化、非质子化和阴离子SMT物质之间直接反应的速率常数已确定分别为1.71 x 10(5)、3.24 x 10(5)和4.18 x 10(5) M(-1)s(-1)。研究发现，pH 5 时，313 nm 处的 SMT 量子产率为每爱因斯坦 0.012 摩尔，pH 7 和 9 时，每爱因斯坦 0.003 摩尔。去除 SMT 的主要贡献是直接臭氧反应、空穴氧化和羟基自由基反应。对于 TOC 的去除，主要贡献在于空穴氧化和羟基自由基反应。 (C) 2008 Elsevier Ltd. 保留所有权利。
The photocatalytic ozonation of sulfamethoxazole (SMT) has been studied in water under different experimental conditions. The effect of gas flow rate, initial concentration of ozone, SMT and TiO(2) has been investigated to establish the importance of mass transfer and chemical reaction. Under the conditions investigated the process is chemically controlled. Both, SMT and TOC kinetics have been considered. Fast and slow kinetic regime of ozone reactions have been observed for SMT and TOC oxidation, respectively. Application of different inhibitors allows for the establishment of reaction mechanism involving direct ozonation, direct photolysis, hydroxyl radical reactions and photocatalytic reactions. Rate constants of the direct reaction between ozone and protonated, non-protonated and anionic SMT species have been determined to be 1.71 x 10(5), 3.24 x 10(5) and 4.18 x 10(5) M(-1)s(-1), respectively. SMT quantum yield at 313 nm was found to be 0.012 moles per Einstein at pH 5 and 0.003 moles per Einstein at pHs 7 and 9. Main contributions to SMT removal were direct ozone reaction, positive hole oxidation and hydroxyl radical reactions. For TOC removal, main contributions were due to positive hole oxidation and hydroxyl radical reactions. (C) 2008 Elsevier Ltd. All rights reserved.