黄壤表面电场作用下Cu~(2+)与Zn~(2+)的吸附/解吸动力学研究

利用静态恒流法研究了黄壤表面电场作用下Cu2+与Zn2+的吸附/解吸动力学.结果发现:考虑黄壤表面电场作用下,Cu2+和Zn2+的吸附实验呈现初期强吸附作用下的零级动力学过程和一定时间之后弱吸附作用下的一级动力学过程,与理论预期一致;在Cu2+和Zn2+的解吸实验中,只有前期出现了弱吸附作用下的一级动力学过程,实验结果与理论预期存在差别,原因在于专性吸附的Cu2+、Zn2+很难被解吸下来;在交换/吸附实验中,Cu2+的吸附速率值和平衡吸附量均大于Zn2+,且Cu2+-K+体系的表面电化学参数φ0、σ0、E0均大于Zn2+-K+体系中的对应值,证明了黄壤颗粒表面对Cu2+的吸附作用强于Zn2+;在交换/解吸实验中,Zn2+的解吸速率值和平衡解吸量均大于Cu2+,Zn2+-K+体系的表面电化学参数φ0、σ0、E0均大于Cu2+-K+体系中的对应值,证明Zn2+-K+体系中Zn2+的解吸作用比Cu2+-K+体系中的Cu2+解吸作用强.

Adsorption and desorption kinetics of Cu2+ and Zn2+ under the electric fields of yellow soil

A study of Cu²⁺ and Zn²⁺ adsorption and desorption kinetics, which are both affected by the electric fields of yellow soil, was conducted by the miscible displacement technique. In this study, some important features of heavy metal ions were discovered. Considering the electric field of yellow soil, in the initial stage of the adsorption experiment, the adsorption process has zero-order kinetics because of strong adsorption followed by first-order kinetics because of weak adsorption.In the desorption experiment, only first order kinetics exist due to weak adsorption in the early stages. The results were different from expectations because the heavy metals were only weakly desorbed.The adsorption rate of Cu²⁺ is higher than that of Zn²⁺. Additionally, the equilibrium adsorption capacity and the surface electrochemistry parameters of Cu²⁺ (Cu²⁺-K⁺ system) are larger than that of Zn²⁺ (Zn²⁺-K⁺ system), which proves that the adsorption of Cu²⁺ is stronger than Zn²⁺ on the surface of the yellow soil. In the desorption experiment, the desorption rate of Zn²⁺ was higher than that of Cu²⁺. Besides, the equilibrium desorption capacity and the surface electrochemistry parameters of Zn²⁺ (Zn²⁺-K⁺ system) were larger than that of the Cu²⁺ (Cu²⁺-K⁺ system), which proves that the desorption of Zn²⁺ is stronger than Cu²⁺ on the surface of the yellow soil.