PDF(Pubmed)
Abstract：
Pb-contaminated soil poses serious hazards to humans and ecosystems and is in urgent need of remediation. However, the extensive use of traditional curing materials such as ordinary Portland cement (OPC) has negatively impacted global ecology and the climate, so there is a need to explore low-carbon and efficient green cementitious materials for the immobilization of Pb-contaminated soils. A red mud/steel slag-based (RM/SS) geopolymer was designed and the potential use of solidifying/stabilizing heavy metal Pb pollution was studied. The Box-Behnken design (BBD) model was used to design the response surface, and the optimal preparation conditions of RM/SS geopolymer (RSGP) were predicted by software of Design-Expert 8.0.6.1. The microstructure and phase composition of RSGP were studied by X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscopy and X-ray photoelectron spectroscopy, and the immobilization mechanism of RSGP to Pb was revealed. The results showed that when the liquid-solid ratio is 0.76, the mass fraction of RM is 79.82% and the modulus of alkali activator is 1.21, the maximum unconfined compressive strength (UCS) of the solidified soil sample is 3.42 MPa and the immobilization efficiency of Pb is 71.95%. The main hydration products of RSGP are calcium aluminum silicate hydrate, calcium silicate hydrate and nekoite, which can fill the cracks in the soil, form dense structures and enhance the UCS of the solidified soil. Pb is mainly removed by lattice immobilization, that is, Pb participates in geopolymerization by replacing Na and Ca to form Si-O-Pb or Al-O-Pb. The remaining part of Pb is physically wrapped in geopolymer and forms Pb(OH)2 precipitate in a high-alkali environment.
摘要：
受铅污染的土壤对人类和生态系统构成严重危害，迫切需要修复。然而,普通硅酸盐水泥(OPC)等传统养护材料的广泛使用对全球生态和气候产生了负面影响，因此，有必要探索低碳高效的绿色胶凝材料用于固定铅污染土壤。设计了一种赤泥/钢渣基（RM/SS）地质聚合物，并研究了固化/稳定重金属Pb污染的潜在用途。采用Box-Behnken设计(BBD)模型设计响应面,并利用Design-Expert8.0.6.1软件预测了RM/SS地质聚合物（RSGP）的最佳制备条件。用X射线衍射仪研究了RSGP的微观结构和相组成,傅里叶变换红外光谱仪,扫描电子显微镜和X射线光电子能谱,揭示了RSGP对Pb的固定化机理。结果表明，当液固比为0.76时，RM的质量分数为79.82％，碱激发剂的模量为1.21，固化土样的最大无侧限抗压强度（UCS）为3.42MPa，Pb的固定效率为71.95％。RSGP的主要水化产物是硅酸铝钙水合物，硅酸钙水合物和nekoite，可以填补土壤中的裂缝，形成致密结构，增强固化土的UCS。Pb主要通过晶格固定去除，也就是说,Pb通过取代Na和Ca形成Si-O-Pb或Al-O-Pb参与地质聚合。Pb的剩余部分物理包裹在地质聚合物中，并在高碱环境中形成Pb（OH）2沉淀物。
