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采用静态实验方法研究了Mn2+在三种黄土性土壤中的吸附动力学和热力学行为。结果表明,黄土性土壤对Mn2+的吸附在90 min内就可达到吸附平衡,对吸附动力学实验数据用吸附动力学模型进行拟合,发现三种黄土性土壤对Mn2+的吸附,都符合Elovich和双常数方程。Mn2+在黄土性土壤中吸附热力学曲线可用Langmuir方程和Freundich方程描述,Freundich等温方程的拟合常数1/n<1,说明吸附过程是优惠吸附;吸附符合Langmuir方程,说明Mn(II)在黄土性土壤中的吸附为单分子层吸附(主要为离子交换作用)。还考察了Na+、Ca2+、Cd2+对黄土性土壤吸附Mn2+的影响,发现Na+对吸附的影响较小,Ca2+、Cd2+使Mn2+在黄土性土壤中的吸附量减小。
Adsorption kinetics and thermodynamic behavior of Mn2 + in three loess soils were studied by static experiments. The results showed that the adsorption equilibrium of Mn2 + in loess soil could be reached within 90 min. The experimental data of adsorption kinetics were fitted by adsorption kinetics model. It was found that the adsorption of Mn2 + by three loess soils accorded with Elovich and Double constant equation. The adsorption thermodynamics curve of Mn2 + in loess soil can be described by Langmuir equation and Freundich equation. The fitting constant of Freundich equation is 1 / n <1, indicating that the adsorption process is preferential adsorption. The adsorption follows the Langmuir equation, indicating that Mn (II) Adsorption in soil is monolayer adsorption (mainly ion exchange). The effects of Na +, Ca2 + and Cd2 + on the adsorption of Mn2 + in loess soil were also investigated. It was found that Na + had little effect on the adsorption, while Ca2 + and Cd2 + decreased the adsorption amount of Mn2 + in loess soil.