Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou, 310058, China; Ningbo Institute of Technology, Zhejiang University, Ningbo, 315100, China.
Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou, 310058, China; Ningbo Institute of Technology, Zhejiang University, Ningbo, 315100, China; Mechanics and Energy Laboratory, Department of Civil and Environmental Engineering, Northwestern University, Evanston, 60208, USA.
Chemosphere. 2020 Dec;260:127646. doi: 10.1016/j.chemosphere.2020.127646. Epub 2020 Jul 11.
Stabilization/solidification (S/S) has been studied since 1950s and widely used for the treatment of potentially toxic elements (PTEs). The coexistence of organic matter (OM) and PTEs can cause a very complicated mechanism for cement-based S/S applications and bring challenges from both scientific and engineering perspectives. To fill in the knowledge gap, this paper investigates for the first time the effects on S/S characteristics of OM components and incubation, which are the two main factors that result in the inconsistency in the leaching characteristics from the available studies. OM samples with different components (humic acid (HA) and fulvic acid (FA)) and contents were mixed into lead-contaminated soil and incubated for different durations of up to 90 days. The experimental results show that the strength of stabilized soils increases with increasing incubation duration and the lead leaching concentration of stabilized soils is decreased by 60.7%-83.6% from zero to 90 days. The lead leaching concentration of the HA group, which is 144.0% higher with no incubation than the non-OM group, becomes 58.3% lower with 90 days of incubation. The leaching concentration of the FA group remains much higher than those of the other groups. Finally, a competing mechanism of HA-weakening cement hydration reactions and stabilizing lead with a critical incubation duration of 14 days-is proposed, together with a cooperating mechanism of FA-weakening cement hydration reactions and releasing lead.
稳定化/固化（S/S）自 20 世纪 50 年代以来就一直在研究，并广泛用于处理潜在有毒元素（PTEs）。有机物（OM）和 PTEs 的共存会导致基于水泥的 S/S 应用出现非常复杂的机制，并从科学和工程角度带来挑战。为了填补这一知识空白，本文首次研究了 OM 成分和孵育对 S/S 特性的影响，这是导致现有研究中浸出特性不一致的两个主要因素。将具有不同成分（腐殖酸（HA）和富里酸（FA））和含量的 OM 样品混入含铅污染的土壤中，并在长达 90 天的不同时间间隔内进行孵育。实验结果表明，稳定化土壤的强度随孵育时间的延长而增加，稳定化土壤中铅的浸出浓度从 0 天到 90 天降低了 60.7%-83.6%。HA 组的铅浸出浓度在没有孵育的情况下比无 OM 组高 144.0%，而在孵育 90 天后则降低了 58.3%。FA 组的浸出浓度仍远高于其他组。最后，提出了一个具有 14 天关键孵育时间的 HA 削弱水泥水合反应和稳定铅的竞争机制，以及 FA 削弱水泥水合反应和释放铅的协同机制。
