Zhang Wenjie, Guo Xingzhang, Sun Zhibin
School of Civil Engineering and Architecture, Taizhou University, Taizhou 318000, PR China.
Institute of Geotechnical and Underground Engineering, Shandong University, Jinan 250061, PR China.
Waste Manag. 2025 Jun 1;200:114766. doi: 10.1016/j.wasman.2025.114766. Epub 2025 Mar 26.
Chromium (Cr)-contaminated soil represents a significant environmental hazard, posing substantial risks to ecological systems. This study investigated the application of Calcium Polysulfide (CPS) and Ground Granulated Blast Furnace Slag (GGBFS) for the stabilization and solidification of Cr-rich soils. The research focused on four key aspects: leachability characteristics, mechanical strength development, hexavalent chromium [Cr(VI)] reduction efficiency, and stabilization mechanisms. Experimental results demonstrated that the treated soil achieved compressive strengths exceeding 2 MPa, indicating its potential suitability as a construction material for roadbeds. Both GGBFS and CPS exhibited strong reducing capabilities, effectively converting highly mobile Cr(VI) to the less mobile trivalent chromium [Cr(III)] species, thereby enhancing Cr stabilization. A reduction ratio of nearly 100 % was achieved with the theoretical dosage of CPS and 30 wt% GGBFS after 56 days of curing. The leached total Cr decreased from 295.6 to 2.1 mg/L, while the leached Cr(VI) concentration decreased from 165.1 mg/L to below the detection limit. The sequential extraction procedure according to Tessier's method demonstrated that chromium was predominantly transformed into more stable fractions, specifically the iron-manganese oxide-bound and residual forms. X-ray diffraction and scanning electron microscopy analyses revealed that the hydration products, predominantly calcium silicate hydrate and ettringite, effectively filled the pores and contributed to the formation of a denser microstructure. The stabilization mechanisms of Cr were identified to involve four key processes: (1) reduction of Cr(VI) to Cr(III), (2) physical encapsulation within the matrix, (3) adsorption onto hydration gels, and (4) ionic substitution of Cr(III) and Cr(VI) into the ettringite structure.
铬（Cr）污染土壤是一种重大的环境危害，对生态系统构成重大风险。本研究调查了多硫化钙（CPS）和粒化高炉矿渣（GGBFS）在富铬土壤稳定化和固化中的应用。研究集中在四个关键方面：浸出特性、力学强度发展、六价铬[Cr(VI)]还原效率和稳定化机制。实验结果表明，处理后的土壤抗压强度超过2MPa，表明其作为路基建筑材料具有潜在适用性。GGBFS和CPS均表现出强大的还原能力，有效地将高迁移性的Cr(VI)转化为迁移性较低的三价铬[Cr(III)]物种，从而增强了铬的稳定性。养护56天后，使用理论剂量的CPS和30wt%的GGBFS实现了近100%的还原率。总铬浸出量从295.6mg/L降至2.1mg/L，而Cr(VI)浸出浓度从165.1mg/L降至检测限以下。根据 Tessier 方法的连续提取程序表明，铬主要转化为更稳定的形态，特别是铁锰氧化物结合态和残留态。X射线衍射和扫描电子显微镜分析表明，水化产物主要是硅酸钙水合物和钙矾石，有效地填充了孔隙并有助于形成更致密的微观结构。确定Cr的稳定化机制涉及四个关键过程：(1) 将Cr(VI)还原为Cr(III)，(2) 在基质内进行物理包裹，(3) 吸附到水化凝胶上，以及(4) 将Cr(III)和Cr(VI)离子置换到钙矾石结构中。
