Probing pollutant reactions at the iron surface: a case study on selenite reactions with nanoscale zero-valent iron,Environmental Science: Nano

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Probing pollutant reactions at the iron surface: a case study on selenite reactions with nanoscale zero-valent iron
Environmental Science: Nano ( IF 5.8 ) Pub Date : 2021-07-27 , DOI: 10.1039/d1en00458a
Qing Huang _{1,

2,

3,

4,

5} , Tianhang Gu _{1,

2,

3,

4,

5} , Airong Liu _{1,

2,

3,

4,

5} , Jing Liu _{1,

2,

3,

4,

5} , Wei-xian Zhang _{1,

2,

3,

4,

5}

Affiliation

Nanoscale zero-valent iron (nZVI) has shown high efficacy for removing selenite (Se(IV)) from water, yet the reaction mechanism in the solid phase, especially the redox transformations of selenite in the oxide layer of nZVI, are not clearly understood. In this study, the speciation and distribution of selenium (Se) in the oxide layer after reactions with nZVI were studied using high-resolution X-ray photoelectron spectroscopy (HR-XPS) with sputter depth profiling, and the speciation and distribution of Se were proven to be depth dependent, with the Se species shifting from Se(IV), Se(IV)/Se(0) to Se(IV)/Se(0)/Se(−II) from the iron oxide shell–water interface to the Fe(0) core. The chemical potential gradient at the water–nZVI interface, where the Fe species change from Fe(III) oxides in the outermost periphery to a mixed Fe(III)/Fe(II) interlayer, then Fe(II) oxide and pure Fe(0) phases, forms a perfect conduit for the electron transfer from the iron core for the reductive transformation of surface-bound Se(IV) pollutants, then driving the Se(IV) reduction to Se(0) and Se(−II). These results reinforce the previous work on the efficacy of nZVI for removing and mitigating heavy metals, and provide strong evidence of the ability of nZVI to separate and enrich Se(IV) from wastewater based upon the fundamentals of the structure–activity relationship.

中文翻译：

探索铁表面的污染物反应：亚硒酸盐与纳米零价铁反应的案例研究

纳米零价铁（nZVI）已显示出从水中去除亚硒酸盐（Se（IV））的高效性，但固相中的反应机理，尤其是亚硒酸盐在 nZVI 氧化层中的氧化还原转化尚不清楚. 在这项研究中，使用高分辨率 X 射线光电子能谱 (HR-XPS) 和溅射深度分析研究了与 nZVI 反应后氧化层中硒 (Se) 的形态和分布，Se 的形态和分布是被证明是深度依赖的，Se 物种从 Se( IV )、Se( IV )/Se(0) 转变为 Se( IV )/Se(0)/Se( -II)) 从氧化铁壳-水界面到 Fe(0) 核。水-nZVI 界面处的化学势梯度，其中 Fe 物种从最外围的Fe( III ) 氧化物变为混合的 Fe( III )/Fe( II ) 夹层，然后是 Fe( II ) 氧化物和纯 Fe( 0) 相，形成了一个完美的电子从铁核转移的管道，用于表面结合的 Se( IV ) 污染物的还原转化，然后推动 Se( IV ) 还原为 Se(0) 和 Se( -II )。这些结果加强了先前关于 nZVI 去除和减轻重金属的功效的工作，并为 nZVI 分离和富集 Se（IV ) 基于结构-活性关系的基本原理来自废水。

更新日期：2021-08-12

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