State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, China.
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
Environ Sci Technol. 2021 Jun 1;55(11):7634-7642. doi: 10.1021/acs.est.1c00375. Epub 2021 Mar 12.
Potassium periodate (PI, KIO) was readily activated by Fe(II) under acidic conditions, resulting in the enhanced abatement of organic contaminants in 2 min, with the decay ratios of the selected pollutants even outnumbered those in the Fe(II)/peroxymonosulfate and Fe(II)/peroxydisulfate processes under identical conditions. Both O isotope labeling techniques using methyl phenyl sulfoxide (PMSO) as the substrate and X-ray absorption near-edge structure spectroscopy provided conclusive evidences for the generation of high-valent iron-oxo species (Fe(IV)) in the Fe(II)/PI process. Density functional theory calculations determined that the reaction of Fe(II) with PI followed the formation of a hydrogen bonding complex between Fe(HO) and IO(HO), ligand exchange, and oxygen atom transfer, consequently generating Fe(IV) species. More interestingly, the unexpected detection of O-labeled hydroxylated PMSO not only favored the simultaneous generation of OH but also demonstrated that OH was indirectly produced through the self-decay of Fe(IV) to form HO and the subsequent Fenton reaction. In addition, IO was not transformed into the undesired iodine species (i.e., HOI, I, and I) but was converted to nontoxic iodate (IO). This study proposed an efficient and environmental friendly process for the rapid removal of emerging contaminants and enriched the understandings on the evolution mechanism of OH in Fe(IV)-mediated processes.
过碘酸钾（PI，KIO）在酸性条件下容易被 Fe(II)激活，导致有机污染物在 2 分钟内得到有效去除，在相同条件下，选定污染物的衰减比例甚至超过了 Fe(II)/过一硫酸盐和 Fe(II)/过二硫酸盐过程。使用甲基苯基亚砜（PMSO）作为底物的 O 同位素标记技术和 X 射线吸收近边结构光谱为 Fe(II)/PI 过程中生成高价铁氧物种（Fe(IV)）提供了确凿的证据。密度泛函理论计算确定，Fe(II)与 PI 的反应遵循 Fe(HO)和 IO(HO)之间形成氢键配合物、配体交换和氧原子转移的顺序，从而生成 Fe(IV)物种。更有趣的是，意外检测到 O 标记的羟基化 PMSO 不仅有利于同时生成 OH，还表明 OH 是通过 Fe(IV)的自衰减形成 HO 和随后的芬顿反应间接产生的。此外，IO 没有转化为不希望的碘化物（即 HOI、I 和 I），而是转化为无毒的碘酸盐（IO）。本研究提出了一种快速去除新兴污染物的高效环保工艺，丰富了对 Fe(IV)介导过程中 OH 演变机制的认识。
