Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, 266237, China.
Huadian Qingdao Power Generation Corporation Limited, Qingdao, 226031, China.
Chemosphere. 2022 Mar;290:133372. doi: 10.1016/j.chemosphere.2021.133372. Epub 2021 Dec 21.
The properties of sulfidated zero-valent iron (S-ZVI) are considered to be determined by the entire structure of Fe and FeS as a whole, but few studies focus on the influence of the morphology and structure of the external FeS layer on the performance of S-ZVI. In this study, after the sulfidation of microscale ZVI in acetate (HAc-NaAc) and 2-(N-morpholino) ethanesulfonic acid (MES) buffer solution, the S-mZVI surface presented the in situ growth of the FeS nanosheet, while the S-mZVI surface was dominated by agglomerated FeS sub-micron particles. Under short-term ultrasonication, S-mZVI was superior to removing Cr(VI) than S-mZVI, and the clearance of the passivation layer by ultrasound maximized the conductivity of the FeS nanosheet to strengthen the sulfidation contribution. However, agglomerated FeS particles were easily separated from S-mZVI by ultrasonication, resulting in the suppression of its sulfidation contribution. The removal of Cr(VI) by S-ZVI increased linearly with FeS content, and the chemical combination of FeS with ZVI had more significant synergy than their physical mixture. The FeS nanosheet with excellent conductivity and large vertical space benefited the generation of dissolved and surface-associated Fe(II) as electron donors and structural Fe(II) as the electron shuttle. Understanding the relationship between FeS structure and S-ZVI performance will pave a way for optimizing the synthesis of S-ZVI.
硫化零价铁（S-ZVI）的性质被认为取决于整个 Fe 和 FeS 的结构，但很少有研究关注外部 FeS 层的形态和结构对 S-ZVI 性能的影响。在这项研究中，在醋酸盐（HAc-NaAc）和 2-（N-吗啉）乙磺酸（MES）缓冲溶液中对微尺度 ZVI 进行硫化后，S-mZVI 表面呈现出 FeS 纳米片的原位生长，而 S-mZVI 表面则由团聚的 FeS 亚微米颗粒主导。在短期超声作用下，S-mZVI 比 S-mZVI 更能去除 Cr(VI)，超声对钝化层的清除最大限度地提高了 FeS 纳米片的导电性，从而增强了硫化作用。然而，团聚的 FeS 颗粒很容易通过超声从 S-mZVI 中分离出来，从而抑制了其硫化作用。S-ZVI 对 Cr(VI)的去除率随 FeS 含量呈线性增加，FeS 与 ZVI 的化学结合比其物理混合物具有更显著的协同作用。具有优异导电性和较大垂直空间的 FeS 纳米片有利于作为电子供体的溶解态和表面结合态 Fe(II)以及作为电子穿梭体的结构态 Fe(II)的生成。了解 FeS 结构与 S-ZVI 性能之间的关系将为优化 S-ZVI 的合成铺平道路。
