Insights into the mechanisms of aqueous Cd(II) reduction and adsorption by nanoscale zerovalent iron under different atmosphere conditions.
Insights into the mechanisms of aqueous Cd(II) reduction and adsorption by nanoscale zerovalent iron under different atmosphere conditions.
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DOI：
10.1016/j.jhazmat.2022.129766
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发表时间：
2022-08
影响因子：
13.6
通讯作者：
Yi-bo Hu;Ting Du;Lihang Ma;Xuening Feng;Yujie Xie;Xiao Fan;Ming‐Lai Fu;Baoling Yuan;
中科院分区：
文献类型：
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作者：
Yi-bo Hu;Ting Du;Lihang Ma;Xuening Feng;Yujie Xie;Xiao Fan;Ming‐Lai Fu;Baoling Yuan;
纳米零价铁(NZVI)可以有效地去除和回收水溶液中的Cd(II)。然而，氧对NZVI去除Cd(II)的影响一直被忽视，研究也不多。X射线光电子能谱(XPS)测得的Cd-MNN螺旋线表明，在厌氧条件下，吸附在NZVI表面的Cd(II)可以被Fe(0)核还原为Cd(0)。在氧气存在的情况下，Cd(II)的去除效率显著下降，表面增厚的γ-FeOOH层抑制了Cd(II)的还原。此外，后氧入侵腐蚀了生成的Cd(0)，并导致Cd(II)离子的剧烈浸出。根据密度泛函理论模拟，Cd(II)在厌氧和好氧条件下的优势表面物种Fe3O4和γ-FeOOH表面的配位作用较好。因此，具有双配位羟基的γ-FeOOH对Cd(II)离子的吸附比Fe3O4少。总体而言，在应用NZVI去除Cd(II)时，应考虑地下修复和废水处理的大气条件。有利的大气条件将提高实际修复Cd(II)污染的基于NZVI的技术的效率和成本效益。
Nanoscale zero-valent iron (NZVI) can effectively remove and recover Cd(II) from aqueous solutions. However, the oxygen effects on Cd(II) removal by NZVI have been overlooked and not well studied. In this research, the Cd MNN auger lines obtained by X-ray photoelectron spectroscopy (XPS) revealed that Cd(II) adsorbed on the NZVI surface could be reduced to Cd(0) by the Fe(0) core under anaerobic conditions. With coexisting oxygen, the Cd(II) removal efficiency declined significantly, and Cd(II) reduction was inhibited by the thickened surface γ-FeOOH layer. Furthermore, the post-oxygen intrusion corroded the generated Cd(0) and led to the dramatic leaching of Cd(II) ions. According to the density functional theory (DFT) simulation, the adsorbed Cd(II) was preferably coordinated via a monodentate model on the surface of Fe3O4and γ-FeOOH, which are the dominant surface species of NZVI under anaerobic and aerobic conditions, respectively. Thus, γ-FeOOH with doubly coordinated hydroxyl groups provided fewer adsorption sites than Fe3O4for Cd(II) ions. Overall, the atmospheric conditions of subsurface remediation and wastewater treatment should be considered when applying NZVI for Cd(II) removal. Favorable atmospheric conditions would improve the efficiency and cost-effectiveness of NZVI-based technologies for the practical remediation of Cd(II) pollution.