土壤颗粒级配对镉吸附-解吸规律的影响

利用甘肃金川某地土壤通过批实验进行等温吸附和动力学解吸实验,研究不同颗粒级配的中砂对镉的吸附、解吸特征,并采用Freundlich和一级动力学方程对其吸附解吸方程进行拟合。结果表明,(1)Freundlich和一级动力学方程对该土壤吸附、解吸镉的实验适用;(2)等温吸附实验中4组不同颗粒级配的中砂对镉的吸附性很强,最大平衡吸附量依次为260.667、286.107、299.362和292.232 mg/kg,吸附性能与颗粒级配中的细粒土相对含量大小成正比;(3)4组土壤对镉的解吸在初期2 h内解吸速率均较快,在3 h左右达到吸附-解吸平衡。平衡后4组土样Ⅰ、Ⅱ、Ⅲ和Ⅳ的最大解吸量依次为0.752、0.561、0.44和0.54 mg/kg,解吸速率和平衡时最大解吸量均与颗粒级配中细颗粒相对含量密切相关。

Effect of soil grain size gradation on sorption and desorption of cadmium

Study on effect of different grain size gradation of the medium sand on adsorption and desorption of Cd was conducted through batch test of isothermal adsorption and desorption dynamic of soil in Jinchuan City of Gansu Province. And adsorption and desorption equations were fitted by Freundlich and one-order dynamic equations. The results show that: (1) Freundlich and one-order dynamic equations are suitable for the test of adsorption and desorption of cadmium in soil. (2) Four groups of medium sand with different grain size gradation have strong adsorption ability to Cd, and the amounts of maximum equilibrium adsorption are 260.667,286.107,299.362,292.232,292.232 mg/kg, respectively. Adsorption ability is proportional to the size of relative content of fine-grained soils. (3) In the early 2 hours, the desorption rates of four groups are faster, and sorption/desorption equilibrium is reached in about 3 hours. Maximum of desorption content are 0.752,0.561,0.44,0.54 mg/kg, respectively after adsorption equilibrium. The desorption rates and maximum of desorption contents are closely correlative to fine particles contents in grain size gradation.