Islam Mohammad Z, Catalan Lionel J J, Yanful Ernest K
Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario, Canada P7B 5E1.
Environ Sci Technol. 2004 Mar 1;38(5):1522-8. doi: 10.1021/es0348400.
Quantitative scanning electron microscope (SEM) studies of cement-stabilized waste specimens exposed to a leaching solution at constant pH in the range 4-7 have shown that the acid neutralization capacity (ANC) of the waste matrix is consumed at two consecutive leaching fronts. The first front is associated with the dissolution of portlandite (Ca(OH)2) and the partial reaction of calcium silicate hydrate (CSH) gel. The second front marks the dissolution of Ca-Al hydroxy sulfate minerals. The advancement of the first front is limited by the diffusion of OH- ions from the first front toward the leaching solution. The advancement of the second front, however, is controlled by the diffusion of H+ ions from the leaching solution toward the second front. Leaching of copper, zinc, and lead only occurs between the second front and the specimen surface. The leaching behavior of metals is modeled by considering that metals are leached from the waste matrix as a result of the advancement of the second front. The proposed model takes into account the leachable metal fraction in the waste matrix and the effect of metal remineralization on metal mobility.
对在pH值为4至7的恒定条件下暴露于浸出液中的水泥稳定废物样本进行的定量扫描电子显微镜（SEM）研究表明，废物基质的酸中和能力（ANC）在两个连续的浸出前沿被消耗。第一个前沿与氢氧化钙（Ca(OH)₂）的溶解以及硅酸钙水合物（CSH）凝胶的部分反应有关。第二个前沿标志着钙铝羟基硫酸盐矿物的溶解。第一个前沿的推进受到OH⁻离子从第一个前沿向浸出液扩散的限制。然而，第二个前沿的推进则由H⁺离子从浸出液向第二个前沿的扩散控制。铜、锌和铅的浸出仅发生在第二个前沿与样本表面之间。通过考虑金属因第二个前沿的推进而从废物基质中浸出，对金属的浸出行为进行了建模。所提出的模型考虑了废物基质中可浸出金属的比例以及金属再矿化对金属迁移率的影响。
