School of Resource and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China.
School of Resource and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China.
J Environ Manage. 2024 Aug;366:121810. doi: 10.1016/j.jenvman.2024.121810. Epub 2024 Jul 14.
Pb-contaminated soil poses significant environmental and health risks as well as soil stability issues. Research on sandy soils highlights CO-enhanced reactive MgO as a promising solution for improving the solidification of Pb-contaminated soils. However, carbonation effects can differ markedly between soil types owing to varying soil properties. In this study, we evaluated the effects of CO-enhanced reactive MgO on the engineering and environmental characteristics of Pb-contaminated red clay and explored its mechanism of carbonation solidification. The results showed that CO-enhanced reactive MgO increased the strength of Pb-contaminated red clay to over 3 MPa within 1 h, which was approximately 25 times the strength of untreated soil (0.2 MPa) and significantly higher than that of reactive MgO-treated, uncarbonated soil (0.8 MPa). The pH of the carbonated soil (9-10) facilitated Pb immobilization, and the increase over the initial parameter elevated the electrical conductivity value. Moreover, CO-enhanced reactive MgO reduced the Pb leaching concentration to below 0.1 mg/L, even at high Pb concentrations (10,000 mg/kg). Pb transformed into lead carbonates during the carbonation process, with the hydrated magnesium carbonates forming a dense internal structure. This solidification mechanism included chemical precipitation, physical adsorption, and encapsulation. Notably, the carbonation time should be controlled within 1 h to prevent soil expansion. Together, these findings support the potential of CO-enhanced reactive MgO for efficient and low-carbon application in the solidification of Pb-contaminated red clay.
受 Pb 污染的土壤会带来重大的环境和健康风险，以及土壤稳定性问题。针对沙质土壤的研究强调，CO 增强的反应性 MgO 是改善受 Pb 污染土壤固化的一种很有前途的解决方案。然而，由于土壤性质的不同，碳酸化作用在不同土壤类型之间可能有显著差异。在这项研究中，我们评估了 CO 增强的反应性 MgO 对受 Pb 污染红黏土的工程和环境特性的影响，并探讨了其碳酸化固化的机理。结果表明，CO 增强的反应性 MgO 在 1 小时内将受 Pb 污染红黏土的强度提高到 3 MPa 以上，这大约是未处理土壤（0.2 MPa）的 25 倍，明显高于未碳酸化反应性 MgO 处理的土壤（0.8 MPa）。碳酸化土壤的 pH 值（9-10）有利于 Pb 的固定，并且比初始参数升高了电导率值。此外，CO 增强的反应性 MgO 将 Pb 的浸出浓度降低到 0.1 mg/L 以下，即使在高 Pb 浓度（10,000 mg/kg）下也是如此。Pb 在碳酸化过程中转化为碳酸铅，水合碳酸镁形成致密的内部结构。这种固化机理包括化学沉淀、物理吸附和封装。值得注意的是，碳酸化时间应控制在 1 小时内，以防止土壤膨胀。总的来说，这些发现支持 CO 增强的反应性 MgO 在受 Pb 污染红黏土的固化中高效、低碳应用的潜力。
