作　　者： ; ; ; ; ; ;

机构地区： 湖南大学环境科学与工程学院

出　　处： 《农业环境科学学报》 2005年第1期84-88,共5页

摘　　要： 以红壤为供试土壤,研究了其在不同pH值下对Cd(Ⅱ)吸附的特性,同时进行了沉淀反应的理论分析。Cd(Ⅱ)的吸附曲线可划分为3区:低pH弱吸附区;中pH值吸附增长区和高pH值强吸附区。根据Cd与土壤间专性吸附化学反应式建立了Cd在土壤中分配系数与pH的线性方程,试验数据按所建方程进行拟合的结果表明,相关系数随pH的升高而显著升高,意味着随pH值的升高,供试红壤对Cd(Ⅱ)的专性吸附作用加强。沉淀反应的理论分析表明,当土壤溶液pH低于11时,沉淀反应都为碳酸盐控制。试验数据的不同吸附模型拟合结果表明,Langmuir能较好地描述Cd(Ⅱ)在红壤里的吸附行为。最后根据Langmuir模型中参数与pH的关系,建立了试验条件下红壤对Cd(Ⅱ)吸附等温线的pH依存方程。 To study the effect of pH on Cd adsorption behavior and species, the red soil was taken as adsorbent. The curve of Cd adsorbed vs. pH showed three stages, namely, the adsorption amount increasing slowly at low pH, then increasing quickly with the rise of pH, and reaching the maximum amount at high pH. According to the specific adsorption reaction between Cd(Ⅱ) and soils, a linear equation relating to the relationship between the partition coefficient of Cd(Ⅱ)in soils and pH was established. The experimental data with regard to the partition coefficients of Cd(Ⅱ) and pH values were fitted to the above-mentioned equation. The correlation coefficients increased significantly with the rise of pH. Meanwhile, the specific adsorption reaction between Cd (Ⅱ) and the red soils used in this study intensified remarkably with the rise of pH. The result of theoretical analysis on precipitation reactions indicated that the precipitationreaction was controlled by carbonate until pH was a little higher than 11. The adsorption data at different pH values and initial Cd (Ⅱ) concentrations were fitted to the Langmuir, Frundlich and Temkin adsorption isotherms and the Langmuir isotherm was the best one to describe the adsorption behavior of Cd in the red soils and was pH-dependent judged from the changes of parameters in Langmuir equation. By substituting the fitting results obtained from the experimental data for the parameters in Langmuir equation, a pH-dependent model of adsorption isotherms of Cd in studied red soils was established under the experimental conditions.

关 键 词： 镉 红壤 吸附行为

领　　域： [环境科学与工程]