Interpretation of Reductive PFAS Defluorination with Quantum Chemical Parameters,Environmental Science & Technology Letters

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Interpretation of Reductive PFAS Defluorination with Quantum Chemical Parameters
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2021-07-01 , DOI: 10.1021/acs.estlett.1c00403
Zhiwen Cheng ₁ , Qincheng Chen ₂ , Zekun Liu ₃ , Jinyong Liu ₃ , Yawei Liu ₁ , Shiqiang Liu ₁ , Xiaoping Gao ₁ , Yujia Tan ₁ , Zhemin Shen _{1,

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Affiliation

Advanced reduction using hydrated electrons (e_aq^–) is a promising technology for the degradation of per- and polyfluoroalkyl substances (PFAS). To better characterize and understand intrinsic factors that influence reductive PFAS defluorination, we probed the relationships between quantum chemical parameters and the reported overall defluorination ratio (deF%) of multiple PFAS structural categories with quantitative structure–activity relationship (QSAR) models. The Fukui index with respect to nucleophilic attack [f(+)], bond order (BO_x), molecular size effect (E_B3LYP), partial charge on carbon atoms [q(C^–)_n], and energy of the lowest unoccupied molecular orbital (E_LUMO) are identified as the influencing factors. The optimal QSAR model with both mechanistic and statistic meanings is log₁₀(deF%) = −4.333 – 68.710E_LUMO – 5.873f(+)_x, with the following evaluation indices: R² = 0.815, q² = 0.728, and Q_ext² = 0.707. The f(+) distribution in PFAS and their degradation intermediates and the optimized structures of excited states support the reported decarboxylation and H/F exchange pathways. This study provides a rapid approach for estimating the overall deF% and gaining new insights into the mechanism of reductive defluorination.

中文翻译：

用量子化学参数解释还原性 PFAS 脱氟

使用水合电子 (e _aq^– ) 的高级还原是一种用于降解全氟和多氟烷基物质 (PFAS) 的有前景的技术。为了更好地表征和理解影响还原性 PFAS 脱氟的内在因素，我们利用定量构效关系 (QSAR) 模型探讨了量子化学参数与多个 PFAS 结构类别的报告总体脱氟率 (deF%) 之间的关系。Fukui 指数与亲核攻击 [ f (+)]、键序 (BO _x )、分子大小效应 ( E _B3LYP )、碳原子上的部分电荷 [ q (C ^– ) _n]，最低未占分子轨道（E _LUMO）的能量被确定为影响因素。具有机械和统计意义的最优 QSAR 模型为 log ₁₀ (deF%) = −4.333 – 68.710 E _LUMO – 5.873 f (+) _x，具有以下评价指标：R ² = 0.815、q ² = 0.728 和Q_分机² = 0.707。该f(+) 在 PFAS 及其降解中间体中的分布以及激发态的优化结构支持报道的脱羧和 H/F 交换途径。这项研究提供了一种快速的方法来估计整体 deF% 并获得对还原脱氟机制的新见解。

更新日期：2021-08-10

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