Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Environ Sci Pollut Res Int. 2017 Dec;24(36):27822-27832. doi: 10.1007/s11356-017-0266-x. Epub 2017 Oct 6.
Cement-based stabilization/solidification (S/S) is a practical treatment approach for hazardous waste with anthropogenic As sources; however, its applicability for geogenic As-containing soil and the long-term leaching potential remain uncertain. In this study, semi-dynamic leaching test was performed to investigate the influence of S/S binders (cement blended with fuel ash (FA), furnace bottom ash (FBA), or ground granulated blast furnace slag (GGBS)) on the long-term leaching characteristics of geogenic As. The results showed that mineral admixtures with higher Ca content and pozzolanic activity were more effective in reducing the leached As concentrations. Thus, cement blended with FBA was inferior to other binders in suppressing the As leaching, while 20% replacement of ordinary Portland cement by GGBS was considered most feasible for the S/S treatment of As-containing soils. The leachability of geogenic As was suppressed by the encapsulation effect of solidified matrix and interlocking network of hydration products that were supported by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results. The long-term leaching of geogenic As from the monolithic samples was diffusion-controlled. Increasing the Ca content in the samples led to a decrease in diffusion coefficient and an increase in feasibility for "controlled utilization" of the S/S-treated soils.
基于水泥的稳定/固化（S/S）是一种处理含人为砷源危险废物的实用方法；然而，其对于含地质砷的土壤的适用性和长期浸出潜力仍不确定。在这项研究中，进行了半动态浸出试验，以研究 S/S 粘结剂（水泥与粉煤灰（FA）、炉底渣（FBA）或磨细高炉矿渣（GGBS）混合）对地质砷长期浸出特性的影响。结果表明，具有较高钙含量和火山灰活性的矿物掺合料在降低浸出砷浓度方面更有效。因此，与其他粘结剂相比，水泥与 FBA 混合在抑制砷浸出方面效果较差，而用 GGBS 替代 20%的普通波特兰水泥被认为是最可行的含砷土壤的 S/S 处理方法。扫描电子显微镜（SEM）、X 射线衍射（XRD）和 X 射线光电子能谱（XPS）结果表明，固化基质的包裹效应和水化产物的联锁网络抑制了地质砷的浸出。地质砷从整体样品中的长期浸出受扩散控制。增加样品中的钙含量会降低扩散系数，并提高 S/S 处理土壤的“可控利用”的可行性。
