Fe/S的循环通常与schwertmannite的形成和命运有关,schwertmannite特别适合作为酸性矿山排水(AMD)中重金属和准金属的清除剂。然而,S(-II)和schwertmannite与结构上掺入的Cr(VI)的反应性之间的相互作用仍然难以捉摸。这项工作评估了溶解实验结合XRD,SEM,FTIR,TEM,和XPS表征,以提供有关S(-II)在pH变化后诱导的schwertmannite转化的详细信息,Cr加载,和S(-II)浓度。我们的结果发现,硫化物的存在显着降低了酸性条件下schwertmannite的稳定性。三个schwertmannite样品的反应性取决于结构上掺入的Cr(VI)的含量,并遵循Sch>0.13Cr-Sch>0.17Cr-Sch的顺序。高S(-II)浓度和低Cr掺杂有利于从schwertmannite中释放Fe和SO42-。Cr迁移率的衰减是通过提高S(-II)浓度和pH值而发生的,从而导致0.13Cr-Sch和0.17Cr-Sch的Cr浓度跨越〜1.39〜0.10mgL-1和〜1.58〜0.12mgL-1,分别。结合表征的结果,针铁矿是主要的最终产物,与硫化物矿物一起构成第二相(FeS,FeS2),氧化铁(Fe3O4,Fe2O3),和CrFe矿物在块状矿物表面。取代的Cr显着抑制了硫化物对Schwertmannite的还原转化,并导致了锂辉石的形成。因此,我们得出的结论是,三阶段转化机制途径控制了schwertmannite向针铁矿的部分转化。这一发现为铁矿物质的生物地球化学过程提供了新的理解,该过程通过减少控制AMD污染区域中固定污染物的运输和命运的物质而受到影响。
The cycling of Fe/S is often related to the formation and fate of schwertmannite which is particularly suitable as a scavenger for heavy metals and metalloids in acid mine drainage (AMD). However, the interactions between reactivity of S(-II) and schwertmannite with structurally incorporated Cr(VI) remain elusive. This work evaluated dissolution experiments in combination with XRD, SEM, FTIR, TEM, and XPS characterization to provide detailed information regarding the transformation of schwertmannite induced by S(-II) following changes in pH, Cr loading, and S(-II) concentration. Our results found that the presence of sulfide significantly decreased the stabilization of schwertmannite under acidic conditions. The reactivity of the three schwertmannite samples depended on the contents of Cr(VI) that were structurally incorporated and followed the order Sch > 0.13Cr-Sch > 0.17Cr-Sch. High S(-II) concentrations and low Cr doping favored the release of Fe and SO42- from schwertmannite. Attenuation of Cr mobility occurred via elevating the S(-II) concentrations and pH values resulting in Cr concentrations spanning ∼1.39 to ∼0.10 mg L-1 and ∼1.58 to ∼0.12 mg L-1 for 0.13Cr-Sch and 0.17Cr-Sch, respectively. Combining the results of characterization, goethite was the dominant end product constituted secondary phase together with sulfide minerals (FeS, FeS2), iron oxides (Fe3O4, Fe2O3), and CrFe minerals on the bulk mineral surface. The substituted Cr significantly inhibited the reductive transformation of schwertmannite by sulfide and led to the formation of lepidocrocite. Thus, we concluded that a three-stage transformation mechanistic pathway governed partial conversion of schwertmannite to goethite. This finding provides new understanding of the biogeochemical processes of iron minerals affected by reducing substances that control the transport and fate of immobilizing contaminants in an AMD-polluted area.