黑土和黑钙土对Cu^(2+)的吸附作用及影响因素

Cu^(2+) Adsorption of Black Soil and Chernozem and Its Influencing Factors

以黑土和黑钙土为供试土壤,采用批量平衡法,研究了pH、离子强度、温度和反应时间对土壤吸附Cu2+的影响。结果表明:随着pH增加,两类土壤对Cu2+的吸附量均增大,pH>7时吸附量达到饱和,黑钙土对Cu2+的吸附量高于黑土;随着反应体系离子强度的增大,两类土壤对Cu2+的吸附率均有所降低,其中在硝酸钠浓度为0~0.2 mol/L时降幅较大;随着温度和溶液中初始Cu2+浓度的升高,两类土壤对Cu2+的吸附量亦有所增加,黑土和黑钙土对Cu2+的吸附等温线分别用Freundlich方程和Langmuir方程描述较为精确,表观热力学参数的计算结果表明两类土壤对Cu2+的吸附均为自发、吸热和熵增加的过程;在描述黑土和黑钙土吸附Cu2+的动力学过程中,Elovich方程和抛物线扩散方程的拟合效果最佳。

Using black soil and chernozem as tested soil, the effects of pH value, ionic strength, temperature and reaction time on adsorption behaviors of Cu2＋ were studied by the batch equilibrium method, which provides basic data for Cu2＋ application and pollution prevention on the two types of soil. The results showed that Cu2＋ adsorption of the two types of soil increased with the increase of pH. When the pH was higher than 7, their adsorption amount was saturated. The amount of Cu2＋ adsorbed by chernozem was higher than that of black soil. However, Cu2＋ adsorption decreased with the increase of ionic strength. The absorption ratio decreased significantly in the NaNO3 solution with the concentration between 0--0. 2 mol/L. With temperature and initial Cu2＋ concentration increasing in the solution, the absorption ratio of Cu2＋ increased in both samples. The best way to describe the relationship between absorption ratio and temperature was Freundlich and Langmuir equations. Apparent thermodynamic parameters showed that Cu2＋absorption of the two types of soil was spontaneous,during which heat was absorbed and entropy was accumulated. For the Cu2＋ adsorption kinetics process, Elovich Equation and Parabolic Diffusion Equation were more available to black soil and chernozem analysis.