水相环境中高岭土对U(Ⅵ)的吸附行为

Adsorption behavior of U(Ⅵ) by kaolin in aqueous environment

以黏土岩矿物组成中的高岭土为研究对象,通过批量吸附实验,探讨其接触时间、高岭土的投加量、U(Ⅵ)的初始质量浓度、水相pH和共存阴阳离子等因素对U(Ⅵ)在高岭土中吸附行为的影响。研究表明:高岭土对溶液中U(Ⅵ)的吸附在12 h达到平衡;高岭土的最佳投加量为0. 03 g; U(Ⅵ)的最佳初始质量浓度为5μg/mL;当pH <9时,Kd值随着pH值的增加而增大,在pH=9时Kd达到最大值; 9种类型的阳、阴离子均对U(Ⅵ)在高岭土中的吸附有抑制作用,其中Ca^(2+),CO_3^(2-)和SO_4^(2-)离子抑制效果最为明显。吸附动力学分析表明:高岭土对U(Ⅵ)的动态吸附平衡遵循准二级动力学模型,其相关系数R2高达0. 999。

Kaolin as a component of clay minerals was studied here,and the effects of the contact time,the feeding amount of kaolin,the initial mass concentration of U(Ⅵ),the pH of aqueous phase and the coexisting cations and anions on adsorption of U(Ⅵ)by kaolin were examined through batch adsorption experiment.The result shows that the adsorption of U(Ⅵ)in the solution by kaolin reaches the equilibrium at 12 h.The optimum feeding amount of kaolin is 0.03 g.The optimum initial mass concentration of U(Ⅵ)is 5μg/mL.When pH<9,the value of K d increases with pH.When pH=9,the value of K d reaches the maximum.9 kinds of anions and cations suppress the adsorption of U(Ⅵ)by kaolin,in which the suppressing effect of Ca^2+,CO3^2-and SO4^2-is the most obvious.Adsorption kinetics analysis shows that the dynamic adsorption equilibrium of U(Ⅵ)by kaolin follows the pseudo-second-order kinetic model,and its correlation coefficient R^2 is up to 0.999.