Department of Chemical & Environmental Engineering, University of California-Riverside, Riverside, California, USA.
Environ Sci Process Impacts. 2017 Mar 22;19(3):395-404. doi: 10.1039/c7em00009j.
Advanced oxidation processes that utilize highly oxidative radicals are widely used in water reuse treatment. In recent years, the application of sulfate radical (SO˙) as a promising oxidant for water treatment has gained increasing attention. To understand the efficiency of SO˙ in the degradation of organic contaminants in wastewater effluent, it is important to be able to predict the reaction kinetics of various SO˙-driven oxidation reactions. In this study, we utilize density functional theory (DFT) and high-level wavefunction-based methods (including computationally-intensive coupled cluster methods), to explore the activation energies of SO˙-driven oxidation reactions on a series of benzene-derived contaminants. These high-level calculations encompass a wide set of reactions including 110 forward/reverse reactions and 5 different computational methods in total. Based on the high-level coupled-cluster quantum calculations, we find that the popular M06-2X DFT functional is significantly more accurate for OH additions than for SO˙ reactions. Most importantly, we highlight some of the limitations and deficiencies of other computational methods, and we recommend the use of high-level quantum calculations to spot-check environmental chemistry reactions that may lie outside the training set of the M06-2X functional, particularly for water oxidation reactions that involve SO˙ and other inorganic species.
高级氧化工艺利用高氧化性自由基广泛应用于水再利用处理。近年来，硫酸根自由基 (SO˙) 作为一种有前途的水处理氧化剂的应用引起了越来越多的关注。为了了解 SO˙ 在降解废水中有机污染物的效率，能够预测各种 SO˙ 驱动的氧化反应的反应动力学是很重要的。在这项研究中，我们利用密度泛函理论 (DFT) 和基于高水准波函数的方法（包括计算密集型耦合簇方法），来探索 SO˙ 驱动的一系列苯衍生污染物氧化反应的活化能。这些高级计算涵盖了广泛的反应，包括 110 个正向/反向反应和总共 5 种不同的计算方法。基于高水准的耦合簇量子计算，我们发现流行的 M06-2X DFT 函数对于 OH 加成比 SO˙ 反应更为准确。最重要的是，我们强调了其他计算方法的一些局限性和缺陷，并建议使用高水准的量子计算来抽查环境化学反应，这些反应可能超出了 M06-2X 函数的训练集，特别是对于涉及 SO˙ 和其他无机物种的水氧化反应。
