School of Resource and Environmental Engineering, Hefei University of Technology, Tunxi Road 193#, Baohe District, Hefei, 230009, People's Republic of China.
Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, People's Republic of China.
Environ Sci Pollut Res Int. 2017 Dec;24(36):28248-28257. doi: 10.1007/s11356-017-0400-9. Epub 2017 Oct 12.
Although the stabilization/solidification method has been widely used for remediation of heavy metal-contaminated soils in recent decades, the engineering behavior and mobility of heavy metal ions under alkaline groundwater conditions are still unclear. Therefore, the unconfined compressive strength test (UCS) combined with toxicity characteristic leaching procedure (TCLP) and general acid neutralization capacity (GANC) was used to investigate the effects of alkalinity (using NaOH to simulate alkalinity in the environment) on the mechanical and leaching characteristics of cement-solidified/stabilized (S/S) Zn-contaminated soils. Moreover, the microstructure was analyzed using the scanning electron microscope (SEM) technology. The results indicated that alkaline environment could accelerate the UCS development compared with specimens without soaking in NaOH solution,, regardless of whether the specimens contained Zn or not. And the UCS varied obviously attributed to the variations of both NaOH concentration and soaking time. Except for the specimens soaked for 90 days, the leached Zn concentrations were higher than that of without soaking. However, the leachability of Zn in all the stabilized specimens is in the regulatory level. ANC results indicated that the Zn leaching behavior can be divided into three stages related to the initial leachate pH. Moreover, SEM results proved that the alkaline environment could actually facilitate the cement hydration process. The results proved in the present paper could be useful in treating the heavy metal-contaminated soils involved in the solidification/stabilization technology under alkaline environment.
虽然稳定/固化方法在最近几十年中已被广泛用于修复重金属污染土壤，但在碱性地下水条件下重金属离子的工程行为和迁移性仍不清楚。因此，采用无侧限抗压强度试验（UCS）结合毒性特征浸出程序（TCLP）和总酸中和能力（GANC）研究了碱度（使用 NaOH 模拟环境中的碱度）对水泥固化/稳定（S/S）Zn 污染土壤的力学和浸出特性的影响。此外，还使用扫描电子显微镜（SEM）技术分析了微观结构。结果表明，与未浸泡在 NaOH 溶液中的试样相比，碱性环境可加速 UCS 的发展，无论试样中是否含有 Zn。而且 UCS 明显变化，这主要是由于 NaOH 浓度和浸泡时间的变化。除浸泡 90 天的试样外，浸出的 Zn 浓度均高于未浸泡的试样。但是，所有稳定化试样中的 Zn 浸出性均处于监管水平。ANC 结果表明，Zn 的浸出行为可分为与初始浸出液 pH 值相关的三个阶段。此外，SEM 结果证明碱性环境实际上可以促进水泥的水化过程。本文的研究结果对于在碱性环境下应用固化/稳定化技术处理重金属污染土壤可能是有用的。
