Abstract

The objective of this study was to investigate the effectiveness of attapulgite modified with five different chlorides (AMNaC, AMCaC, AMMgC, AMFeC, and AMAlC) in improving attapulgite performance and its potential for immobilizing heavy metals in polluted soil. The contaminated soil was treated with attapulgite-modified chlorides as a passivating agent to stabilize Cd, Pb, Cr, and Zn pollutants, while untreated soil served as the control. Various techniques, including scan electron microscope (SEM), X-ray diffraction (XRD), and stability analysis were employed to evaluate the modifications. The bioavailability and stability of heavy metals were assessed using the TCLP and CaCl₂ extraction to determine Cd, Pb, Cr, and Zn concentrations. The BCR method was conducted to investigate changes in the speciation of heavy metals in soils stabilized by attapulgite-modified chloride compounds. SEM and XRD analysis demonstrated that the attapulgite-modified chlorides were uniformly dispersed and well-fixed on the superficies of the attapulgite particles. Following the addendum of attapulgite-modified chloride, the soil pH increased by 1.33 units, while EC, CEC, OM, and N showed slight increases. The toxicity characterized leaching procedure results indicated significant reductions in Cd, Pb, Cr, and Zn concentrations, with decreases ranging from 3.80 to 1.20 mg/kg, 15.00 to 4.40 mg/kg, 3.00 to 0.80 mg/kg, and 24.16 to 10.70 mg/kg, respectively. Furthermore, after the incubation period, the residual proportions of Cd, Pb, Cr, and Zn increased by 32.04%, 39.01%, 36.03%, and 39.01%, respectively. Overall, utilizing attapulgite-modified chlorides effectively reduced the bio-availability and mobility of heavy metals in the soil.

中文翻译：

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氯化物改性凹凸棒土对土壤重金属形态和环境风险的影响

摘要

本研究的目的是研究用五种不同氯化物（AMNaC、AMCaC、AMMgC、AMFeC 和 AMAlC）改性的凹凸棒石在改善凹凸棒石性能方面的有效性及其固定污染土壤中重金属的潜力。用凹凸棒石改性氯化物作为钝化剂处理污染土壤，以稳定镉、铅、铬和锌污染物，而未处理的土壤作为对照。采用各种技术，包括扫描电子显微镜（SEM）、X射线衍射（XRD）和稳定性分析来评估修饰。使用 TCLP 和 CaCl ₂萃取测定 Cd、Pb、Cr 和 Zn 浓度来评估重金属的生物利用度和稳定性。 BCR 方法用于研究凹凸棒土改性氯化物稳定土壤中重金属形态的变化。 SEM和XRD分析表明凹凸棒石改性氯化物均匀分散并良好固定在凹凸棒石颗粒的表面。添加凹凸棒土改性氯化物后，土壤pH值增加了1.33个单位，而EC、CEC、OM和N略有增加。浸出过程的毒性特征结果表明，Cd、Pb、Cr 和 Zn 浓度显着降低，降低范围为 3.80 至 1.20 mg/kg、15.00 至 4.40 mg/kg、3.00 至 0.80 mg/kg 和 24.16 至 10.70 mg /kg，分别。此外，培养期结束后，Cd、Pb、Cr和Zn的残留比例分别增加了32.04%、39.01%、36.03%和39.01%。总体而言，利用凹凸棒土改性氯化物有效降低了土壤中重金属的生物有效性和迁移率。