Mechanism and influence factors of chromium(VI) removal by sulfide-modified nanoscale zerovalent iron
Mechanism and influence factors of chromium(VI) removal by sulfide-modified nanoscale zerovalent iron
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硫化物改性纳米零价铁去除六价铬的机理及影响因素
DOI：
10.1016/j.chemosphere.2019.02.109
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发表时间：
2019-06-01
期刊：
影响因子：
8.8
通讯作者：
Xu, Xinhua
中科院分区：
文献类型：
--
作者：
Lv, Dan;Zhou, Jiasheng;Xu, Xinhua
纳米级零价铁 (nZVI) 的硫化引起了越来越多的关注，以提高 nZVI 对各种污染物的反应性和选择性，例如去除水性 Cr(VI)。然而，硫化物改性对去除 Cr(VI) 的好处仍不清楚，本工作对此进行了研究。 S/Fe摩尔比较高的S-nZVI表现出较高的表面积，不同S/Fe的S-nZVI对Cr(VI)的表面积归一化去除能力之间的差异表明，Cr(VI)的去除还受到其他因素的影响，如电子转移能力、表面束缚的Fe(II)物种和表面电荷。高比表面积将为去除 Cr(VI) 提供更多的活性位点，并且作为有效的电子导体，针状 FeS(x ) 相也有利于电子从 Fe-0 核转移到 Cr(VI)。较低的初始pH也增强了Cr(VI)的去除，并且S-nZVI和nZVI的Cr(VI)去除能力不受老化过程的影响，这些结果证实了Fe(II)物种在Cr(VI)的去除中也发挥了重要作用。还研究了其他影响因素的潜在应用，包括温度、初始 Cr(VI) 浓度、离子强度和共存离子。 S-nZVI去除Cr(VI)的机理包括硫化物改性以增加比表面积并提供更多的活性位点，Fe-0的腐蚀产生表面结合的Fe(II)物种以吸附Cr(VI)物种，随后由于FeSx的电子转移能力而有利于Cr(VI)还原为Cr(III)，然后形成Cr(III)/Fe(III)氢氧化物沉淀。 (C) 2019 Elsevier Ltd. 保留所有权利。
Sulfidation of nanoscale zerovalent iron (nZVI) has attracted increasing interest for improving the reactivity and selectivity of nZVI towards various contaminants, such as aqueous Cr(Vl) removal. However, the benefits derived from sulfide modification that govern the removal of Cr(VI) remains unclear, which was studied in this work. S-nZVI with higher S/Fe molar ratio showed higher surface area, the discrepancy between the surface-area-normalized removal capacity of Cr(VI) by S-nZVI with different S/Fe indicated that the removal of Cr(VI) was also affected by other factors, such as electron transfer ability, surface-bounded Fe(II) species, and surface charges. High specific surface area would provide more active site for Cr(VI) removal, and as an efficient electron conductor, acicular-like FeS(x )phase would also favor electron transfer from Fe-0 core to Cr(VI). Low initial pH also enhanced the Cr(VI) removal, and the Cr(VI) removal capacity by S-nZVI and nZVI was not affected by aging process, these results confirmed that the Fe(II) species also played an important role in the Cr(VI) removal. Other influence factors were also investigated for potential application, including temperature, initial Cr(VI) concentration, ionic strength, and co-existed ions. The removal mechanism of Cr(VI) by S-nZVI involved the sulfide modification to increase the specific surface area and provide more active sites, the corrosion of Fe-0 to produce surface-bounded Fe(II) species to adsorb Cr(VI) species, followed by the favored reduction of Cr(VI) to Cr(III) due to the electron transfer ability of FeSx, then the formation of Cr(III)/Fe(III) hydroxides precipitates. (C) 2019 Elsevier Ltd. All rights reserved.