National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Engineering Research Center for Non-point Source Pollution Control, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, 510650, PR China; International Institute of Soil and Water Conservation, Meizhou, 514000, PR China.
South China Research Institute on Geotechnical Engineering, South China University of Technology, Guangzhou, 510641, China.
Chemosphere. 2021 Mar;267:128926. doi: 10.1016/j.chemosphere.2020.128926. Epub 2020 Nov 16.
The use of stabilized/solidified (S/S) soils and sediments as sustainable construction materials is a global concern due to the potential risk of contaminant leaching including potentially toxic elements. The long-term leachability of four metals (Zn, Pb, Cd and As) in sediments mixed with OPC (Ordinary Portland Cement) and OPC/GGBS (Ground Granulated Blast Furnace Slag) binders were investigated through a combination of tank leaching tests and kinetic leaching models, with varying ranges of curing ages and ambient pH. The leaching data revealed that both binder compositions offer an excellent immobilization capacity for the four metals, while their releases are strongly pH-dependent and are a complex function of curing time. The partial replacement of OPC by GGBS is more effective for fixing Zn and As at pH of 1, Pb at pH of 7, Zn and Pb at pH of 10. Controlling leaching mechanisms and leachability indices were determined using nonlinear regression analysis and kinetic leaching models. The first-order diffusion model (FRDM) was the most applicable model for describing the leaching characteristics of these metals under the investigated cases, the leaching rate is controlled by surface wash-off initially and then by diffusion. The leachability indices indicate that the cement-slag S/S sediment can be regarded as an environmentally sustainable material with potential beneficial uses in construction.
将稳定化/固化（S/S）土壤和沉积物用作可持续建筑材料是一个全球性的关注点，因为存在污染物浸出的潜在风险，包括潜在的有毒元素。通过组合罐浸出试验和动力学浸出模型，研究了与普通波特兰水泥（OPC）和 OPC/矿渣（磨细高炉矿渣）结合剂混合的沉积物中四种金属（Zn、Pb、Cd 和 As）的长期浸出性，其养护龄期和环境 pH 值变化范围较大。浸出数据表明，两种结合剂成分对四种金属都具有优异的固定能力，而它们的释放强烈依赖于 pH 值，并与养护时间呈复杂的函数关系。用矿渣部分替代 OPC 更有利于在 pH 值为 1 时固定 Zn 和 As、在 pH 值为 7 时固定 Pb、在 pH 值为 10 时固定 Zn 和 Pb。通过非线性回归分析和动力学浸出模型确定了控制浸出机制和浸出指数。在研究案例中，一阶扩散模型（FRDM）是描述这些金属浸出特性最适用的模型，浸出速率最初受表面冲刷控制，然后受扩散控制。浸出指数表明，水泥-矿渣 S/S 沉积物可用作环境可持续材料，在建筑中有潜在的有益用途。
