The mobility and fate of heavy metals in soils is of environmental concern. Stirred-flow experiments were conducted to study the competitive sorption and desorption of Zn, Ni, and Pb in binary systems in acidic Olivier loam soil. For all three binary systems, consecutive pulse applications demonstrated that the metal of highest affinity displaced sorbed amounts of metals of low affinity, whereas sorbed concentrations of the ion of highest affinity were unaffected by the addition of the metal of lower affinity. The displacement of Ni by Zn appeared irreversible, whereas the displacement of Zn by Pb and Ni by Pb was reversible. A two-site competitive kinetic model consisting of common and ion-specific sites successfully described the experimental data. Specifically, the model was able to accurately predict lower sorbed concentrations in concurrent pulse studies, as well as the displacement of Ni by Zn and Zn by Pb in the consecutive pulse studies. The presented model provided significant improvement over single-ion models that have been previously used to describe competitive interactions between species in stirred flow experiments.

中文翻译：

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模拟酸性土壤中 Zn(II)、Ni(II) 和 Pb(II) 的竞争吸附和解吸动力学：搅拌流实验

土壤中重金属的流动性和归宿是环境问题。进行了搅拌流实验，研究了酸性 Olivier 壤土中 Zn、Ni 和 Pb 在二元体系中的竞争吸附和解吸。对于所有三个二元系统，连续脉冲应用表明，亲和力最高的金属取代了低亲和力金属的吸附量，而亲和力最高的离子的吸附浓度不受添加低亲和力金属的影响。Ni 被Zn 置换似乎是不可逆的，而Pb 对Zn 的置换和Pb 对Ni 的置换是可逆的。由常见和离子特异性位点组成的双位点竞争动力学模型成功地描述了实验数据。具体来说，该模型能够准确预测并发脉冲研究中较低的吸附浓度，以及连续脉冲研究中 Ni 被 Zn 置换和 Zn 被 Pb 置换。与以前用于描述搅拌流实验中物种之间的竞争性相互作用的单离子模型相比，所提出的模型提供了显着的改进。