Benitez F Javier, Real Francisco J, Acero Juan L, Garcia Carolina
Departamento de Ingeniería Química, Universidad de Extremadura, 06071 Badajoz, Spain.
Water Res. 2007 Oct;41(18):4073-84. doi: 10.1016/j.watres.2007.05.041. Epub 2007 Jun 3.
Oxidation of four phenyl-urea herbicides (isoproturon, chlortoluron, diuron, and linuron) was studied by ozone at pH=2, and by a combination of O3/H2O2 at pH=9. These experiments allowed the determination of the rate constants for their reactions with ozone and OH radicals. For reactions with ozone, the following rate constants were obtained: 1.9 +/- 0.2, 16.5 +/- 0.6, 393.5 +/- 8.4, and 2191 +/- 259 M(-1) s(-1) for linuron, diuron, chlortoluron, and isoproturon, respectively. The rate constants for the reaction with OH radicals were (7.9 +/- 0.1) x 10(9) M(-1) s(-1) for isoproturon, (6.9 +/- 0.2) x 10(9) M(-1) s(-1) for chlortoluron, (6.6 +/- 0.1) x 10(5) M(-1) s(-1) for diuron, and (5.9 +/- 0.1) x 10(9) M(-1) s(-1) for linuron. Furthermore, the simultaneous ozonation of these selected herbicides in some natural water systems (a commercial mineral water, a groundwater, and surface water from a reservoir) was studied. The influence of operating conditions (initial ozone dose, nature of herbicides, and type of water systems) on herbicide removal efficiency was established, and the parameter Rct (proposed by Elovitz, M.S., von Gunten, U., 1999. Hydroxyl radical/ozone ratios during ozonation processes. I. The Rct concept. Ozone Sci. Eng. 21, 239-260) was evaluated from simultaneous measurement of ozone and OH radicals. A kinetic model was proposed for the prediction of the elimination rate of herbicides in these natural waters, and application of this model revealed that experimental results and predicted values agreed fairly well. Finally, the partial contributions of direct ozone and radical pathways were evaluated, and the results showed that reaction with OH radicals was the major pathway for the oxidative transformation of diuron and linuron, even when conventional ozonation was applied, while for chlortoluron and isoproturon, direct ozonation was the major pathway.
研究了臭氧在pH = 2时以及O3/H2O2在pH = 9时对四种苯基脲类除草剂（异丙隆、绿麦隆、敌草隆和利谷隆）的氧化作用。这些实验确定了它们与臭氧和羟基自由基反应的速率常数。对于与臭氧的反应，分别得到利谷隆、敌草隆、绿麦隆和异丙隆的速率常数为1.9±0.2、16.5±0.6、393.5±8.4和2191±259 M⁻¹ s⁻¹。与羟基自由基反应的速率常数分别为：异丙隆(7.9±0.1)×10⁹ M⁻¹ s⁻¹、绿麦隆(6.9±0.2)×10⁹ M⁻¹ s⁻¹、敌草隆(6.6±0.1)×10⁵ M⁻¹ s⁻¹、利谷隆(5.9±0.1)×10⁹ M⁻¹ s⁻¹。此外，还研究了在一些天然水体系（一种商业矿泉水、一种地下水和一个水库的地表水）中对这些选定除草剂的同时臭氧化作用。确定了操作条件（初始臭氧剂量、除草剂性质和水体系类型）对除草剂去除效率的影响，并通过同时测量臭氧和羟基自由基来评估参数Rct（由Elovitz, M.S., von Gunten, U.于1999年提出。臭氧化过程中的羟基自由基/臭氧比率。I. Rct概念。臭氧科学与工程21, 239 - 260）。提出了一个动力学模型来预测这些天然水中除草剂的去除率，该模型的应用表明实验结果和预测值相当吻合。最后，评估了直接臭氧途径和自由基途径的部分贡献，结果表明，即使采用常规臭氧化，与羟基自由基的反应也是敌草隆和利谷隆氧化转化的主要途径，而对于绿麦隆和异丙隆，直接臭氧化是主要途径。
