Departamento de Ingeniería Química. Universidad de Extremadura, Avenida de Elvas S/N, 06006 Badajoz, Spain.
Departamento de Ingeniería Química. Universidad de Extremadura, Avenida de Elvas S/N, 06006 Badajoz, Spain.
J Hazard Mater. 2015 Jan 23;282:224-32. doi: 10.1016/j.jhazmat.2014.05.085. Epub 2014 Jun 5.
The ozonation of 1H-benzotriazole (BZ) and 3-methylindole (ML), two emerging contaminants that are frequently present in aquatic environments, was investigated. The experiments were performed with the contaminants (1μM) dissolved in ultrapure water. The kinetic study led to the determination of the apparent rate constants for the ozonation reactions. In the case of 1H-benzotriazole, these rate constants varied from 20.1 ± 0.4M(-1)s(-1) at pH=3 to 2143 ± 23 M(-1)s(-1) at pH=10. Due to its acidic nature (pKa=8.2), the degree of dissociation of this pollutant was determined at every pH of work, and the specific rate constants of the un-dissociated and dissociated species were evaluated, being the values of these rate constants 20.1 ± 2.0 and 2.0 ± 0.3 × 10(3)M(-1)s(-1), respectively. On the contrary, 3-methylindole does not present acidic nature, and therefore, it can be proposed an average value for its rate constant of 4.90 ± 0.7 × 10(5)M(-1)s(-1) in the whole pH range 3-10. Further experiments were performed to identify the main degradation byproducts (10 mg L(-1) of contaminants, 0.023 gh(-1) of ozone). Up to 8 intermediates formed in the ozonation of 3-methylindole were identified by LC-TOFMS, while 6 intermediates were identified in the ozonation of 1H-benzotriazole. By considering these intermediate compounds, the reaction mechanisms were proposed and discussed. Finally, evaluated rate constants allowed to predict and modeling the oxidation of these micropollutants in general aquatic systems.
研究了 1H-苯并三唑（BZ）和 3-甲基吲哚（ML）这两种经常存在于水生环境中的新兴污染物的臭氧化作用。实验在超纯水中溶解污染物（1μM）进行。动力学研究确定了臭氧化反应的表观速率常数。对于 1H-苯并三唑，这些速率常数在 pH=3 时从 20.1 ± 0.4M(-1)s(-1)变化到 pH=10 时的 2143 ± 23 M(-1)s(-1)。由于其酸性（pKa=8.2），在每个工作 pH 值下都确定了该污染物的离解度，并评估了未离解和离解物种的特定速率常数，这些速率常数的值分别为 20.1 ± 2.0 和 2.0 ± 0.3×10(3)M(-1)s(-1)。相反，3-甲基吲哚没有酸性，因此可以提出其在整个 pH 范围 3-10 内的平均速率常数为 4.90 ± 0.7×10(5)M(-1)s(-1)。进一步的实验用于鉴定主要的降解副产物（污染物 10mgL(-1)，臭氧 0.023gh(-1)）。通过 LC-TOFMS 鉴定了 3-甲基吲哚臭氧化过程中形成的 8 种中间体，而在 1H-苯并三唑臭氧化过程中鉴定了 6 种中间体。考虑到这些中间化合物，提出并讨论了反应机制。最后，评估的速率常数允许预测和模拟这些微污染物在一般水生系统中的氧化。
