One-time removal of Cr(VI) and carbon tetrachloride from groundwater by silicate stabilized green rust: The slow release of reactive sites driven by Fe (III)-Cr(III) oxides formation

作者：Zhao, Jinxin; Xiong, Shuting; Chen, Fengmin; Yin, Weizhao^*; Gong, Yanyan; Wu, Jinhua; Huang, Li-Zhi^*; Dionysiou, Dionysios D.

来源：Chemical Engineering Journal, 2022, 433: 134462.

DOI：10.1016/j.cej.2021.134462

• Combined pollution
• Fe(II) solids
• Chromium
• Chlorinated compounds
• Soil and groundwater remediation

Green rusts (GRs) are materials with strong reducing ability useful for soil and groundwater remediation. In this study, we synthesized GR(Cl)-Si with green rust chloride (GR(Cl)) by using silicate for stabilization and evaluated its capacity for simultaneous removal of Cr(VI) and carbon tetrachloride (CT). Cr(VI) acted as a promoter to accelerate CT removal by GR(Cl)-Si, while GR(Cl)-Si could barely degrade CT in its absence. Further analyses of aqueous Fe(II) concentration, Cr(VI) species evolution, and transformations of solid phases showed that Cr(VI) could react with GR(Cl) and initiate structural changes to form GR(OX)-Cr(III) precipitates, which exhibited stronger adsorption of silicate than GR(Cl). Adsorption experiments showed that GR(OX)-Cr(III) precipitates might abstract silicate from GR(Cl)-Si to expose reactive sites of GRCl. These experiments demonstrated that the GROX-Cr(III) functions as an adsorbent and promoter to accelerate CT dechlorination by GR(Cl)-Si rather than as an inhibitor of further redox reactions. This study reveals the positive effect of Cr(VI) on CT dechlorination by stabilized GRs and highlights the importance of Fe(III)-Cr(III) precipitation and environmental behavior during the remediation of contaminated sites polluted with Cr(VI) and chlorinated compounds by using minerals with high iron contents. These findings are valuable for in-situ remediation of combined pollution of heavy metals and organic compounds, which is also be implicational for development and diversification of soil and groundwater remediation technology.

• 单位
  武汉大学