赤泥增强磷酸镁水泥用于修复 Pb 和 As 污染土壤。
Red mud-enhanced magnesium phosphate cement for remediation of Pb and As contaminated soil.
机构信息
Institute of Construction Materials, Technische Universität Dresden, 01062, Dresden, Germany; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
出版信息
J Hazard Mater. 2020 Dec 5;400:123317. doi: 10.1016/j.jhazmat.2020.123317. Epub 2020 Jun 26.
Lead (Pb) and arsenic (As) contaminated soil poses severe threats to human health. This study proposes a novel approach for synchronous stabilisation/solidification (S/S) of Pb and As contaminated soil and explains the immobilisation mechanisms in red mud-modified magnesium phosphate cement (MPC). Experimental results show that incorporation of red mud in MPC binder retarded over-rapid reaction and enhanced compressive strength via the formation of (Al,Fe,K)PO·nHO compounds as indicated by X-ray diffractometer (XRD) and elemental mapping. The presence of Pb had a marginal effect on the MPC reaction; however, the presence of As suppressed the generation of MgKPO·6HO, leading to a significant delay of setting time and a reduction of compressive strength. Extended X-ray absorption fine structure (EXAFS) analysis proved that Pb strongly coordinated with the PO, whereas AsO- gently coordinated with K. The MPC binder displayed an excellent immobilisation efficiency for Pb (99.9%), but was less effective for As. The use of red mud enhanced the As immobilisation efficacy to 80.5% due to strong complexation between AsO- and Fe. The treated soils fulfilled requirements of metal(loid) leachability and mechanical strength for on-site reuse. Therefore, red mud-modified MPC can be an effective binder for sustainable remediation of Pb and As contaminated soil.
含铅（Pb）和砷（As）污染的土壤对人类健康构成严重威胁。本研究提出了一种同步稳定化/固化（S/S）污染土壤中 Pb 和 As 的新方法，并解释了赤泥改性磷酸镁水泥（MPC）中固定化的机理。实验结果表明，赤泥的掺入延缓了 MPC 胶凝材料的过快反应，通过形成（Al、Fe、K）PO·nHO 化合物提高了抗压强度，X 射线衍射仪（XRD）和元素映射表明这一点。Pb 的存在对 MPC 反应影响不大；然而，As 的存在抑制了 MgKPO·6HO 的生成，导致凝结时间显著延迟和抗压强度降低。扩展 X 射线吸收精细结构（EXAFS）分析证明，Pb 与 PO 强烈配位，而 AsO-与 K 配位较弱。MPC 胶凝材料对 Pb 的固定化效率达到 99.9%，但对 As 的固定化效率较低。赤泥的使用由于 AsO-和 Fe 之间的强络合作用，提高了 As 的固定化效率，达到 80.5%。处理后的土壤满足金属（类）浸出性和现场再利用的力学强度要求。因此，赤泥改性 MPC 可以成为一种可持续修复 Pb 和 As 污染土壤的有效胶凝材料。
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