School of Resources and Environmental Science, Wuhan University, Wuhan, 430079, PR China.
School of Resources and Environmental Science, Wuhan University, Wuhan, 430079, PR China; Hubei Academy of Environmental Science, Wuhan, 430072, PR China.
Chemosphere. 2021 Jan;263:128142. doi: 10.1016/j.chemosphere.2020.128142. Epub 2020 Aug 28.
Iron species have essential influence on the environmental/geochemical behaviors of arsenic species in water and soil. Colloidal ferric hydroxide (CFH) induces photooxidation of arsenite (As(III)) to arsenate (As(V)) in water at neutral pH through surface complexation and ligand-to-metal charge transfer (LMCT). However, the effect of the co-existing natural organic matter (NOM) on the complexation-photolysis in this process has remained unclear. In the present work, the photooxidation of As(III) induced by CFH was investigated in the presence of various carboxylic acids and polyphenols as simple model compounds of NOM. Two different light sources of ultraviolet A (UVA) (λ = 365 nm) and ultraviolet B (UVB) (λ = 313 nm) were used for photooxidation treatment of the experimental ternary system and the control binary system respectively. The obtained results demonstrated that all investigated NOM inhibited the photooxidation of As(III) in the As(III)/CFH system at pH 7. Moreover, the correlation analysis between the pseudo-first order rate constant k and various property parameters of NOM showed that the stable constant for the complexation between Fe(III) and NOM (logK) as well as the molecular weight of NOM and the percentages of total acidity of NOM exhibited significant correlations. A simple quantitative structure-activity relationship (QSAR) model was established between k and these three parameters utilizing a multiple linear regression method, which can be employed to estimate the photooxidation efficiency of As(III) in the presence of ferric iron and NOM. Thus, the present work contributes to the understanding of the environmental interactions between NOM and iron.
铁物种对砷物种在水和土壤中的环境/地球化学行为有重要影响。胶体氢氧化铁（CFH）通过表面络合和配体到金属电荷转移（LMCT）诱导中性 pH 下水中亚砷酸盐（As(III)）向砷酸盐（As(V)）的光氧化。然而，共存的天然有机物（NOM）对该过程中络合-光解的影响仍不清楚。在本工作中，研究了 CFH 存在下各种羧酸和多酚作为 NOM 的简单模型化合物对 As(III)的光氧化作用。使用两种不同的光源，即紫外线 A（UVA）（λ=365nm）和紫外线 B（UVB）（λ=313nm），分别对实验三元体系和对照二元体系进行光氧化处理。所得结果表明，所有研究的 NOM 在 pH 7 下均抑制 As(III)/CFH 体系中 As(III)的光氧化。此外，k 值与 NOM 各种性质参数之间的相关分析表明，Fe(III)与 NOM 之间络合的稳定常数（logK）以及 NOM 的分子量和 NOM 的总酸度百分比与 k 值之间存在显著相关性。利用多元线性回归方法，在 k 值和这三个参数之间建立了一个简单的定量构效关系（QSAR）模型，该模型可用于预测铁和 NOM 存在下 As(III)的光氧化效率。因此，本工作有助于理解 NOM 和铁之间的环境相互作用。
