College of Civil Engineering and Architecture, Wenzhou University, Wenzhou, 325035, China.
College of Environmental Protection, Zhejiang Industry and Trade Vocational College, Wenzhou, 325002, China.
Environ Geochem Health. 2024 Aug 21;46(10):383. doi: 10.1007/s10653-024-02148-3.
Traditional cement solidifying or stabilizing heavy metal-contaminated sites often face issues like alkalinity loss, cracking, and poor long-term performance. Therefore, bentonite-supported nano-zero-valent iron (B-nZVI) was introduced to optimize the remediation effect of cement in this paper. The effects of B-nZVI, ordinary Portland cement (OPC), and B-nZVI + OPC on the chemical stability of heavy metals and the physical strength of lead-contaminated soil were compared using semi-dynamic leaching methods, BCR tests, unconfined strength analysis, and micro-assisted analysis. Results demonstrated that the addition of B-nZVI effectively enhanced the remediation efficacy of OPC on lead-contaminated soil. The combination of B-nZVI and OPC exhibited a synergistic repair effect, offering superior physical strength and chemical stability for lead remediation. B-nZVI facilitated the adsorption and enrichment of Pb, thereby reducing oxidizable lead and enhancing short-term stabilization. Meanwhile, OPC precipitation and silicate gelling stabilized exchangeable lead into the residual form, necessitating repeated hydration gelling. Additionally, B-nZVI's sealing effect via water absorption delayed the leaching of exchangeable lead, thereby reducing lead migration. Even with only 1% B-nZVI added to the 12% OPC base, the leaching amount of Pb decreased significantly from 67.6 to 6.59 mg/kg after 7 d of curing. The unconfined strength of contaminated soil treated with the composite solidifying agent for 7 d was 12.87% higher than that of OPC alone, and for 28 d, it was 36.48% higher. This optimization scheme presents a promising approach for effective and sustainable remediation of heavy metal-contaminated sites.
传统的水泥固化/稳定化技术在处理重金属污染场地时，常常面临碱度损失、开裂和长期性能不佳等问题。因此，本文引入膨润土负载纳米零价铁（B-nZVI）来优化水泥的修复效果。采用半动态浸出法、BCR 测试、无侧限抗压强度分析和微观辅助分析，对比了 B-nZVI、普通波特兰水泥（OPC）和 B-nZVI+OPC 对重金属化学稳定性和铅污染土壤物理强度的影响。结果表明，B-nZVI 的添加有效增强了 OPC 对铅污染土壤的修复效果。B-nZVI 和 OPC 的组合表现出协同修复效应，为铅修复提供了更好的物理强度和化学稳定性。B-nZVI 促进了 Pb 的吸附和富集，从而减少了可氧化铅的含量，增强了短期稳定性。同时，OPC 沉淀和硅酸盐胶凝将可交换铅稳定为残余形态，需要反复进行水化胶凝。此外，B-nZVI 通过吸水的密封作用延迟了可交换铅的浸出，从而减少了铅的迁移。即使在 12% OPC 基础上仅添加 1%的 B-nZVI，在 7 天固化后，Pb 的浸出量从 67.6 降至 6.59 mg/kg，降幅显著。用复合固化剂处理污染土壤 7 天后，无侧限抗压强度比单独使用 OPC 时提高了 12.87%，28 天后提高了 36.48%。该优化方案为有效和可持续修复重金属污染场地提供了一种有前途的方法。
