School of Water Resource and Environment, Research Center of Environmental Science and Engineering, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian District, Beijing, 100083, China; Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
School of Water Resource and Environment, Research Center of Environmental Science and Engineering, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian District, Beijing, 100083, China.
Chemosphere. 2022 Nov;307(Pt 4):135892. doi: 10.1016/j.chemosphere.2022.135892. Epub 2022 Aug 17.
In this study compound-specific isotope analysis (CSIA) has been used to explore the degradation mechanism of nano titanium dioxide (TiO) catalyzes photodegradation of diethyl phthalate (DEP). TiO is a popular photosensitizer with potential in waste water treatment and application in advanced oxidation processes. The degradation process of DEP can be described with a first-order kinetics in the applied concentration ranges. The larger degradation rate constant has been found at neutral conditions. The C and H isotope fractionation associated with the nano TiO catalyzes photodegradation of DEP at pH 3, 7 and 11 yield normal isotope effects. In the TiO/UV/DEP and TiO/HO/UV/DEP systems, the correlation of C and H fractionation (Λ) were calculated to be 2.7 ± 0.2, 2.8 ± 0.2 at pH 3, 2.2 ± 0.4, 2.5 ± 0.2, 2.3 ± 0.6 at pH 7 and 2.6 ± 0.3, 2.2 ± 0.3, 2.7 ± 0.2 and 2.3 ± 0.3 at pH11, respectively. The dominant free radical species in studied systems were explored by combining free radical quenching method and electron paramagnetic resonance analysis. The hydroxyl radicals have been found as the main radical species at all pH conditions studied. Furthermore, the C and H fractionation suggested that the addition of •OH on the benzene ring of DEP is the main conversion pathway. Therefore, CSIA is a promising technology for the identification of reaction pathways of DEP for example in water treatment systems.
在这项研究中，我们使用了化合物特定同位素分析（CSIA）来探索纳米二氧化钛（TiO）催化邻苯二甲酸二乙酯（DEP）光降解的降解机制。TiO 是一种在废水处理和高级氧化工艺中有潜在应用的流行光催化剂。在应用浓度范围内，DEP 的降解过程可以用一级动力学来描述。在中性条件下发现了较大的降解速率常数。在 pH 值为 3、7 和 11 的条件下，纳米 TiO 催化 DEP 光降解过程中与 C 和 H 同位素分馏相关的正常同位素效应。在 TiO/UV/DEP 和 TiO/HO/UV/DEP 体系中，计算出 C 和 H 分馏（Λ）的相关性分别为 2.7±0.2、2.8±0.2 在 pH 值为 3 时，2.2±0.4、2.5±0.2、2.3±0.6 在 pH 值为 7 时，2.6±0.3、2.2±0.3、2.7±0.2 和 2.3±0.3 在 pH 值为 11 时。通过结合自由基猝灭法和电子顺磁共振分析，探讨了研究体系中主要自由基种类。在所有研究的 pH 条件下，均发现羟基自由基是主要的自由基种类。此外，C 和 H 同位素分馏表明，•OH 加成到 DEP 的苯环上是主要的转化途径。因此，CSIA 是一种有前途的技术，可用于鉴定例如在水处理系统中 DEP 的反应途径。
