重金属铜在黑土和棕壤中解吸行为的比较

采用一次平衡法研究吸附态Cu²⁺在黑土和棕壤上的解吸行为并进行了比较.结果表明,与棕壤相比,黑土吸附态Cu²⁺解吸有更长的滞后阶段,黑土在Cu²⁺的吸附量低于729.00mg·kg^-1(Cu²⁺处理浓度小于40 mg·L^-1),棕壤在Cu²⁺的吸附量低于393.29 mg·kg^-1(Gu²⁺处理浓度小于20 mg·L^-1)时,土壤吸附态Cu²⁺几乎不发生解吸.2种土壤吸附态Cu²⁺的解吸率均较低,尤其是黑土.在试验所采用的Gu²⁺处理浓度范围内,黑土与棕壤吸附态Cu²⁺的最高解吸率分别为6.60%和13.56%.Freundlich方程为描述2种土壤Cu²⁺等温解吸过程的最佳方程.黑土和棕壤吸附态Cu²⁺的解吸速率均较快,在40min左右基本达到平衡.描述黑土和棕壤解吸动力学过程的最优模型为双常数速率方程,其次为Elovich方程.

Comparison on Desorptive Behavior of Copper in Phaeozem and Burozem

Desorptive behavior of Cu²⁺ from phaeozem and burozem was studied and compared using the batch method. The results indicated that Cu²⁺ desorbed from phaeozem tested had a longer lag period than that from burozem. When adsorbed Cu²⁺ for phaeozem was lower than 729.00 mg·kg^-1 (Cu²⁺ concentration was lower than 40 mg·L^-1), and on burozem was lower than 393.29 mg·kg^-1 (Cu²⁺ concentration was lower than 20 mg·L^-1), adsorbed Cu²⁺ was hardly desorbed. Meanwhile, the desorption ratio of Cu²⁺ from the two soils were both low, especially for phaeozem. In the range of Cu²⁺ concentration used in the experiments, the desorption rate maximums of Cu²⁺ for phaeozem and burozem were respectively 6.60% and 13.56%. Freundlich equation could best describe desorption isotherm processes of Cu²⁺ from the two soils. Adsorbed Cu²⁺ on soils was desorbed so fast from phaeozem and burozem that the desorption equilibrium could be reached only after 40 min desorption. The best model to describe Cu²⁺ desorption kinetics was two-constant equations, followed by the Elovich equation.