酸性条件下粉砂质壤土对Cd^(2+)的吸附解吸特性研究  

Effect of different acidic conditions on the adsorption-desorption characteristics of Cd^(2+) in a silt loam

作　　者：张德乐[1,2] 靳孟贵[1,2] 方远[3] 周迅[2,4] 余梅[1,2] 

机构地区：[1]中国地质大学生物地质与环境地质国家实验室,湖北武汉430074 [2]中国地质大学(武汉)环境学院,湖北武汉430074 [3]中南建筑设计院股份有限公司,湖北武汉430074 [4]南京地质调查中心,江苏南京210016

出　　处：《中国土壤与肥料》2014年第4期29-34,共6页Soil and Fertilizer Sciences in China

基　　金：高等学校博士学科点基金(20100145110010);中国地质调查局地下水污染调查项目(1212011121169)

摘　　要：为了解酸性条件下粉砂质壤土对Cd2+的吸附-解吸机制,采用一次平衡法进行了不同pH值条件下壤土对Cd2+的吸附-解吸实验。结果表明:壤土对Cd2+的吸附量和吸附率均随着pH值升高而增加,不同初始浓度下达到的最大吸附率为0.69~0.95,酸性条件下壤土对Cd2+的等温吸附Freundlich方程拟合效果最好,通过拟合的Langmuir方程计算出壤土对Cd2+的饱和吸附量为2 500 mg/kg。Cd2+的解吸量和解吸前的吸附量呈显著正相关线性关系,解吸率随着pH值升高而减小,pH值从2以等间隔1变化到6,平均解吸率依次为1.11、0.33、0.07、0.06、0.06;表明在酸性污水灌溉条件下污灌壤土中的镉易向下迁移,污染深层土壤和地下水。Batch experiments were used to study the adsorption-desorption mechanisms of Cd2＋ in a silt loam under acidic con-ditions. The results showed that, the amount of adsorption and the ratio of adsorption of Cd2＋ increased with the increasing of pH values. Under different initial concentration, the maximum adsorption rate was 0. 69 -0. 95. The isotherm sorption of Cd2＋ onto loam under acidic conditions fitted best to Freundlich model. The Langmuir model illustrated that the maximum sorp-tion capacity of Cd2＋ of the soil was 2 500 mg/kg. The amount of desorption increased with the increasing of adsorption and they were remarkably correlated linerarly. The ratio of desorption to adsorption decreased with pH increase. When pH in-creased from 2 to 6, the average desorption ratios for Cd2＋ were 1. 11, 0. 33, 0. 07, 0. 06, and 0. 06, respectively, which implies that Cd2＋ easily migrates down and pollute deep soil and groundwater under acid sewage irrigation.

关 键 词：pH值 酸性条件 壤土 Cd2+ 吸附-解吸 

分 类 号：S152.3[农业科学—土壤学] O647.3[农业科学—农业基础科学]