岩溶区典型土壤对Cd^(2+)的吸附特性  

Cd^(2+) adsorption characteristics of typical soils in karst areas

作　　者：朱丹尼 邹胜章[2] 周长松[2] 李录娟[2] 卢海平[2] 

机构地区：[1]中国地质大学,北京100083 [2]中国地质科学院岩溶地质研究所/国土资源部广西壮族自治区岩溶动力学重点实验室,广西桂林541004

出　　处：《中国岩溶》2015年第4期402-409,共8页Carsologica Sinica

基　　金：国土资源部地质调查项目(1212011121166);973计划课题项目(2011CB201001);中国地质科学院岩溶地质研究所基本科研业务费项目(2014030)

摘　　要：文章采用有序批试验,就岩溶区两种典型石灰土(棕色、黑色石灰土)对Cd2+的吸附行为进行研究。试验结果表明:石灰土对重金属Cd2+具有较强的吸附能力(平均吸附率范围89.84~98.84),黑色石灰土的吸附能力高于棕色石灰土,吸附量随平衡浓度的增加而增大;Langmuir和Freundlich方程均能很好地描述两种石灰土对Cd2+的等温吸附过程,Freundlich方程拟合最优;两种石灰土吸附镉的动力学特征相似,吸附过程可分为快速反应、慢速反应和吸附平衡3个阶段,棕色石灰土对Cd2+吸附动力学的最优模型为Elovich方程和双常数方程(R>0.9),黑色石灰土仅在Cd2+初始浓度为100mg/L条件下,Elovich方程、双常数方程和WM方程的模拟达到较显著水平(R>0.8);有机质、碳酸钙含量及CEC值是影响石灰土对Cd2+吸附能力的主控因素,铁、铝、硅氧化物含量对Cd2+吸附影响不大;综合热力学、动力学及影响因素分析认为石灰土对Cd2+吸附机理包括土壤颗粒表面官能团的专性吸附及不均匀粒内扩散、静电作用等非专性吸附过程。The problem of cadmium （as Cd and Cd~＋）pollution is prominent in karst areas. This paper studies it adsorption property to reveal the migration of Cd2＋ in the soil environment, thus providing a scientific basis for the environmental risk assessment of the soils. Adsorption of Cd2＋ by calcareous soils （brown calcareous soil,black calcareous soil） in the karst areas was investigated via batch sorption experiments. The resuits show a higher sorption capacity of calcareous soil to the heavy metal Cd, with the mean adsorption rate ranging from 89.84 to 98.84, of which black calcareous soil is greater than that of brown calcareous soil. The isothermal adsorption process of the both calcareous soils can be satisfactorily described by Langmuir and Freundlich models, while simulative result of the latter is better than that of the former. In the meantime, the Elovich,two-coefficient,W-M and first-order models are used to simulate the soil Cd2＋ sorption kinetics. On the one hand, the Elovich and two-coefficient equayions represent the best models to simulate the adsorption kinetics of Cd2＋ in brown calcareous soil with the correlation coefficients in excess of 0.9. On the other hand, the adsorption kinetics of Cd2＋ in black calcareous soils only fits the Etovich,two-coefficient and W-M equations with the significance level of above 0.8. The simulations for the black calcareous are processed with an initial Cd concentration of 100 mg/L, where the Elovich model is proved to be the best one. Moreover, the soil property analyses show that the contents of organic matters, calcium carbonate and CEC have a significant impact on the adsorption capacities of the soils studied, while the contents of iron, aluminum and silicon oxides in the soils show a minor influence on their Cd absorption capacities.

关 键 词：岩溶 石灰土 Cd2+ 吸附 

分 类 号：X53[环境科学与工程—环境工程]