Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha, Hunan, 410083, PR China.
Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha, Hunan, 410083, PR China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, PR China.
Chemosphere. 2023 Apr;321:138132. doi: 10.1016/j.chemosphere.2023.138132. Epub 2023 Feb 11.
Effective remediation of Cr(VI)-contaminated soil with strong alkalinity and high Cr(VI) concentration is a severe challenge. Herein, a proton-buffering montmorillonite-supported sulfidated nano zerovalent iron (nFeS/Fe@H-Mt) was developed for remediation of alkaline Cr(VI)-contaminated soil. The reductive efficiencies of water-soluble Cr(VI) reached 99.7%, 99.3% and 99.8% in three tested soils with initial concentrations of 439.6, 3307.5 and 4626.7 mg kg, respectively, after 15 d of nFeS/Fe@H-Mt treatment. Further speciation analyses demonstrated most available Cr species (exchangeable and carbonate-bound Cr) were transformed into more stable Cr species. The leachable Cr(VI) and total Cr obtained by toxicity leaching procedures decreased to extremely low levels and maintained long-term stability for 120 d. Such superior reductive immobilization performance of FeS/Fe@H-Mt was attributed to the synergistic effect of sulfidated nano zerovalent iron and proton-buffering montmorillonite, which induced the coordination of proton donation and electron transfer. The proton-buffering montmorillonite (H-Mt) could prevent the aggregation of nanoparticles and provide protons to accelerate the corrosion of Fe. In addition, the FeS component improved electron selectivity and facilitated electron transfer of Fe to Cr(VI). Our study demonstrated that the coordination of proton donation and electron transfer significantly enhanced the Cr(VI) reduction under the alkaline condition thus leading to effective remediation of alkaline Cr(VI)-contaminated soil.
有效修复强碱性和高六价铬浓度污染土壤是一项严峻的挑战。本文制备了质子缓冲蒙脱石负载硫化纳米零价铁（nFeS/Fe@H-Mt）用于碱性六价铬污染土壤的修复。在三种初始浓度分别为 439.6、3307.5 和 4626.7 mg kg 的污染土壤中，nFeS/Fe@H-Mt 处理 15 d 后，水相六价铬的还原效率分别达到 99.7%、99.3%和 99.8%。进一步的形态分析表明，大部分可利用的铬形态（可交换态和碳酸盐结合态铬）转化为更稳定的铬形态。毒性浸出程序得到的可浸出六价铬和总铬含量降低到极低水平，并在 120 d 内保持长期稳定性。FeS/Fe@H-Mt 具有优异的还原固定性能，这归因于硫化纳米零价铁和质子缓冲蒙脱石的协同作用，诱导了质子供体配位和电子转移。质子缓冲蒙脱石（H-Mt）可以防止纳米颗粒的聚集，并提供质子以加速 Fe 的腐蚀。此外，FeS 组分提高了电子选择性并促进了 Fe 向 Cr(VI)的电子转移。本研究表明，质子供体配位和电子转移的协同作用显著增强了碱性条件下的 Cr(VI)还原，从而有效修复了碱性 Cr(VI)污染土壤。
