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(VI) 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 Fe⁰ 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 Fe⁰ 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 FeS_x, then the formation of Cr(III)/Fe(III) hydroxides precipitates.

纳米级零价铁（nZVI）的硫化已引起人们越来越多的兴趣，他们希望提高nZVI对各种污染物（例如Cr（VI）水溶液的去除）的反应性和选择性。但是，硫化物修饰所带来的控制Cr（VI）去除的好处仍然不清楚，对此工作进行了研究。S / Fe摩尔比较高的S-nZVI的表面积较大，不同S / Fe的S-nZVI的表面积标准化去除Cr（VI）的能力之间的差异表明Cr（VI）的去除为还受其他因素的影响，例如电子转移能力，表面结合的Fe（II）种类和表面电荷。高比表面积将为去除Cr（VI）提供更多的活性部位，并且作为有效的电子导体，呈针状FeS _x相也将有利于电子从Fe ⁰核转移到Cr（VI）。较低的初始pH值也增强了Cr（VI）的去除，并且S-nZVI和nZVI去除Cr（VI）的能力不受老化过程的影响，这些结果证实Fe（II）物种在氧化过程中也起了重要作用。去除六价铬。还研究了其他可能的应用影响因素，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）的机理涉及硫化物改性，以增加比表面积并提供更多的活性部位，以及对Fe ⁰的腐蚀产生表面结合的Fe（II）物种以吸附Cr（VI）物种，然后由于FeS _x的电子转移能力而将Cr（VI）有利地还原为Cr（III），然后形成Cr（III） ）/ Fe（III）氢氧化物沉淀。