The relative adsorption selectivities of Pb, Cu, Zn, Cd and Ni by soils developed on shale in New Valley, Egypt
The relative adsorption selectivities of Pb, Cu, Zn, Cd and Ni by soils developed on shale in New Valley, Egypt
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DOI：
10.1016/j.geoderma.2007.12.004
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发表时间：
2008-03
期刊：
影响因子：
6.1
通讯作者：
A. Usman
中科院分区：
文献类型：
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作者：
A. Usman
重金属与土壤的反应对于确定这些金属在环境中的生物有效性和最终归宿非常重要。为了评估的竞争吸附和选择性序列的铅，铜，锌，镉和镍，批平衡实验进行了使用的混合物的金属溶液和表面样品的六个埃及土壤上开发的页岩和不同的物理化学和矿物学性质。结果表明，Langmuir吸附等温线可以很好地描述所有研究的重金属。Cd和Ni在大多数土壤中的吸附行为相似，而Pb、Cu和Zn的吸附行为则不同。金属固/液分配系数（Kd），这代表了吸附亲和力的金属阳离子在溶液中的固相，计算的总初始添加浓度的重金属。Pb的Kd值最高（0.29-1647 L kg−1），其次是Cu（0.21-813 L kg−1）。然而，Zn（0.17-118 L kg−1）、Ni（0.08-163 L kg−1）和Cd（0.04-45 L kg−1）的Kd值较低。由Kd值可知，重金属吸附的选择性顺序为Pb>Cu>Zn>Ni>Cd，这与第一水解平衡常数有关。简单相关和多元回归分析表明，土壤吸附重金属的能力与粘粒类型（主要是蒙脱石）、粘粒含量以及阳离子交换量有关。
Reactions of heavy metals with soils are important in determining the bioavailability and the ultimate fate of these metals in the environment. To assess the competitive sorption and the selectivity sequence of Pb, Cu, Zn, Cd and Ni, batch equilibrium experiments were performed using a mixture of metal solutions and surface samples of six Egyptian soils that were developed on shale and differed in their physicochemical and mineralogical properties. The results indicated that the Langmuir isotherm could well describe the adsorption of all studied heavy metals. The sorption behaviours of Cd and Ni were similar to each other in the most studied soils, while those of Pb, Cu and Zn were different. Metal solid/liquid distribution coefficients (Kd), which represent the adsorption affinity of the metallic cations in solution for the solid phase, were calculated the overall initial added concentrations of heavy metals. The highest Kdvalues were found for Pb (0.29–1647 L kg−1) and followed by Cu (0.21–813 L kg−1). However, low Kdvalues were shown for Zn (0.17–118 L kg−1), Ni (0.08–163 L kg−1) and Cd (0.04–45 L kg−1). On the basis of the Kdvalues, the most common selectivity sequence of the metal adsorption is Pb>Cu>Zn>Ni>Cd, which it is related to the first hydrolysis equilibrium constant. Generally, the simple correlation and the multiple regression analysis suggest that the ability of the soil to adsorb heavy metals depends upon the type (mainly, smectites) and the amount of clay, as well as the CEC.