Department of Civil Engineering, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.
School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.
J Environ Manage. 2023 Oct 15;344:118395. doi: 10.1016/j.jenvman.2023.118395. Epub 2023 Jun 19.
Contamination of soils by arsenic represents a significant environmental and public health risk, making effective remediation strategies a pressing concern. One commonly employed technique is stabilization and solidification, which involves the addition of stabilizing binders such as cement to immobilize arsenic. This study investigates the potential of alkaline activated slag for stabilization and solidification of arsenic-contaminated soil, employing the toxic characteristic leaching procedure (TCLP) and unconfined compressive strength (UCS) tests. To assess the strength and leachability behavior, the research examines the effect of several factors, including binder content, curing time, curing conditions, alkaline activator solution to slag ratio, sodium silicate to sodium hydroxide ratio, and sodium hydroxide concentration. Additionally, field emission scanning electron microscopes (FE-SEM) in combination with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) tests are employed to analyze the stabilization and solidification mechanism. The study shows that increasing the slag content to 20% by weight after 28 days of curing at ambient temperature leads to a decrease of almost 92% in the concentration of leached arsenic and an increase in UCS from 80 kPa to approximately 19 MPa. The formation of albite and anorthite crystals, along with gels such as (N, C)-A-S-H and C-S-H, contributes to enhanced strength and reduced leachability. As a result, the use of alkaline activated slag is identified as an effective and environmentally friendly approach for the stabilization/solidification of arsenic-contaminated soils. This study highlights the use of alkaline activated slag as an effective solution for remediating arsenic-contaminated soils while simultaneously reducing waste, greenhouse gas emissions, and energy consumption. Slag, a byproduct of metal production, is often wasted due to a lack of value and landfill space. However, alkaline activated slag demonstrates the potential to stabilize soil, immobilize heavy metals, and provide efficient and sustainable soil remediation.
砷污染土壤对环境和公共健康构成重大风险，因此，寻求有效的修复策略成为当务之急。一种常用的技术是稳定和固化，它涉及添加稳定化粘结剂，如水泥，以固定砷。本研究采用毒性特征浸出程序（TCLP）和无侧限抗压强度（UCS）试验，研究了碱性激活矿渣对砷污染土壤的稳定和固化潜力。为了评估强度和浸出行为，研究考察了几种因素的影响，包括粘结剂含量、养护时间、养护条件、碱性激活剂溶液与矿渣的比例、硅酸钠与氢氧化钠的比例以及氢氧化钠浓度。此外，还采用场发射扫描电子显微镜（FE-SEM）结合能谱（EDS）和 X 射线衍射（XRD）试验分析稳定和固化机制。研究表明，在环境温度下养护 28 天后，将矿渣含量增加到 20%（重量），可使浸出砷浓度降低近 92%，UCS 从 80kPa 增加到约 19MPa。钠长石和钙长石晶体以及凝胶（如（N，C）-A-S-H 和 C-S-H）的形成有助于提高强度和降低浸出率。因此，碱性激活矿渣的使用被确定为一种有效且环保的方法，可用于稳定/固化砷污染土壤。本研究强调了碱性激活矿渣作为一种有效的解决方案，用于修复砷污染土壤，同时减少废物、温室气体排放和能源消耗。矿渣是金属生产的副产品，由于缺乏价值和填埋空间，通常被浪费。然而，碱性激活矿渣具有稳定土壤、固定重金属以及提供高效和可持续土壤修复的潜力。
