镉和铅在2种典型土壤中的吸附及其与温度的关系  

Adsorption of Cadmium and Lead in Two Typical Soils as Affected by Temperature

作　　者：王金贵[1] 吕家珑[1] 曹莹菲[1] 

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《水土保持学报》2011年第6期254-259,共6页Journal of Soil and Water Conservation

基　　金：公益性行业(农业)专项(200903015)

摘　　要：采用批平衡法研究我国2种典型土壤对镉和铅的吸附特性及其与温度的关系,运用热力学参数ΔG°、ΔH°和ΔS°解释土壤镉和铅的吸附机理,并对镉和铅在复合共存情况下的吸附特性进行讨论。结果表明,镉和铅在土壤中的吸附过程表现出明显的非线性,镉和铅的吸附分别符合Freundlich模型和Lang-muir模型。塿土对镉和铅的最大吸附量和最大缓冲容量均大于红壤的。镉和铅复合共存时,2种重金属的吸附均受到抑制;温度升高时,镉和铅对彼此的抑制作用有所减弱。吉布斯自由能变ΔG°为负值表明镉和铅吸附反应为自发反应;ΔH°为正值表明土壤对镉和铅的吸附为吸热反应。单一存在时,镉在塿土和红壤中的主要作用力分别为氢键和范德华力;而铅在塿土和红壤中的主要作用力均为范德华力。复合共存时,镉和铅的主要作用力发生改变。Batch experiments were carried out to study the adsorption of cadmium （Cd） and lead （Pb） in two typical soils distributed in China at two different temperatures （25 ℃ and 40 ℃）. And thermodynamic pa- rameters, like △G°、△H°and△S° were used to explain mechanism of the adsorption. The effects of interac- tion between Cd and Pb on their adsorption were also discussed. The results showed that adsorption of Cd and Pb displayed nonlinear curves that fitted the Freundlich model and Langmuir model, respectively. The maximum adsorption and maximum buffer capacity of Cd and Pb in the lou soil higher than red soil. The co- existence of Cd and Pb suppressed the adsorption of Cd and Pb, and the effect was reduced as the tempera- ture increased. The negative values of △G° suggested that adsorption of Cd and Pb was a spontaneous process. The positive △H° values indicated that adsorption of Cd and Pb was an endothermic process. When the Cd and Pb was single in the solution, for the Cd, the H bonds force and Van Der Waals force were the major force in lou soil and red soil, and for the Pb, the Van Der Waals force was the major force in two soils. However, the coexistence of Cd and Pb made the major force change.

关 键 词：镉 铅 吸附 温度 

分 类 号：S153[农业科学—土壤学]