Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing, 210096, China; Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing, 211189, China.
Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing, 210096, China; Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing, 211189, China; Jiangsu Province Key Laboratory of Environmental Engineering, Jiangsu Provincial Academy of Environmental Science, Nanjing, 210036, China.
Chemosphere. 2022 Aug;301:134644. doi: 10.1016/j.chemosphere.2022.134644. Epub 2022 Apr 19.
Soils with relatively high concentrations of arsenic (As) and antimony (Sb) in mining areas would impose significant risks to human health and ecosystem. A new stabilizer PFSC composed of polymerized ferric sulfate (PFS) and calcium hydroxide (Ca(OH)) is proposed to stabilize the soil with co-existed As and Sb sampled at an abandoned arsenic factory site. The effects of stabilizer dosage on the properties of the stabilized soil including leached concentrations of As and Sb, unconfined compressive strength (UCS), and hydraulic conductivity (k) were investigated. The mechanisms of As and Sb immobilization in the soils were interpreted by Tessier's sequential extraction procedure (SEP), scanning electron microscope (SEM), and X-ray diffraction (XRD) results. The results showed increasing PFSC dosage was effective for reducing leached concentrations of As and Sb. When the PFSC dosage increased from 2% to 10%, the UCS and k increased from 84 to 206 kPa and decreased from 6.48 × 10 to 6.33 × 10 m s, respectively. Tessier's SEP results showed that the leachable As and Sb fractions decreased from 12% to 5.6% and 7.5% to 3.8%, while the Fe-Mn oxides bound fractions increased from 22.3% to 29.4% and 13.2% to 19.5%. The SEM images and XRD patterns of untreated and PFSC stabilized contaminated soils indicated that hematite and calcite (CaCO) were the main products of PFSC stabilization processes. Adsorption on ferrihydrite, entrapment in hematite lattices, and co-precipitate with calcite might were the main mechanisms of As and Sb immobilization.
矿区土壤中砷（As）和锑（Sb）浓度相对较高，会对人类健康和生态系统造成重大风险。本研究提出了一种新型稳定剂 PFSC，由聚合硫酸铁（PFS）和氢氧化钙（Ca(OH)）组成，用于稳定在废弃砷厂场地采集的同时含有 As 和 Sb 的土壤。考察了稳定剂剂量对稳定土壤性能的影响，包括浸出的 As 和 Sb 浓度、无侧限抗压强度（UCS）和水力传导系数（k）。通过 Tessier 连续提取程序（SEP）、扫描电子显微镜（SEM）和 X 射线衍射（XRD）结果解释了 As 和 Sb 固定的机制。结果表明，增加 PFSC 剂量可有效降低浸出的 As 和 Sb 浓度。当 PFSC 剂量从 2%增加到 10%时，UCS 和 k 分别从 84 kPa 增加到 206 kPa 和从 6.48×10-7 m s-1 降低到 6.33×10-7 m s-1。Tessier 的 SEP 结果表明，可浸出的 As 和 Sb 分数从 12%降低到 5.6%和 7.5%降低到 3.8%，而 Fe-Mn 氧化物结合分数从 22.3%增加到 29.4%和 13.2%增加到 19.5%。未处理和 PFSC 稳定污染土壤的 SEM 图像和 XRD 图谱表明，赤铁矿和方解石（CaCO）是 PFSC 稳定化过程的主要产物。吸附在水铁矿上、进入赤铁矿晶格中以及与方解石共沉淀可能是 As 和 Sb 固定的主要机制。
