重金属镉在黑土和棕壤中的解吸行为比较

Comparison on Desorptive Behavior of Cadmium in Phaeozem and Burozem

采用一次平衡法对Cd2+在黑土和棕壤2种土壤类型中的解吸行为进行了比较研究.结果表明,Cd2+在2种土壤中的解吸行为均有明显的滞后性.相对于棕壤,Cd2+在黑土中的解吸有更长的滞后阶段.Cd2+在2种土壤中的解吸过程是一个快速反应的过程,当解吸平衡时间在30min左右时,吸附态Cd2+的解吸量能达到总解吸量的90%以上.Cd2+在2种土壤中的解吸效率都比较低,相对于总吸附量而言,Cd2+在黑土和棕壤的解吸百分比分别低于9.0%和15.1%.解吸速率随着初始浓度的增加而升高,但随着解吸量和解吸时间增加而下降,土壤性质对解吸速率的下降并没有明显的影响.Freundlich方程是描述Cd2+在这2种土壤中等温解吸的最佳方程,而Elovich方程是描述其在这2种土壤中解吸动力学变化的最佳方程.

Desorptive behavior of Cd^2＋ was comparatively studied by the batch method on the two typical soils in northeast China. The results indicated that the two soils exhibit statistically significant sorption-desorption hysteresis. Phaeozem has a longer hysteresis period than the Burozem. The desorptive behavior of Cd^2＋ in the two tested soils was a rapid reactions, which could account for 90 % of the Cd^2＋ equilibrium desorption within the first 30min. Compared with the total adsorption, the desorptive percentage of the adsorped Cd^2＋ in the phaeozem and burozem was in a low extent, which was ranged within rate of 9.0 % and 15.1% respectively, The desorptive rates of Cd^2＋ in the soils were increased with the higher concentrations of Cd^2＋ in the treatments, and decreased with the increasing desorptive amount and time. Soil properties had no significant effect on the desorptive rate decreasing. Freundlich equation was the optimal model to describe the desorptive isotherm of Cd^2＋ , while the Elovich equation was the best model to describe Cd^2＋ desorption kinetics in the two soils.