模拟酸雨下H+-Ca2+在红壤表面的动力学特征

研究模拟酸雨下H Ca2 在红壤表面的反应动力学吸附特征 ,结果表明 :Ca2 的吸附动力学能很好地用一级动力学方程、抛物线扩散方程和Elovich方程 (R2 >0 97)拟合 .随溶液酸度的增加 ,Ca2 的最大吸附量显著降低 ,Ca2 吸附反应速率控制步骤是离子在颗粒内的扩散 ,扩散速率常数随酸度的增加而下降 .酸溶液pH值为 4 5和 5 6时 ,有H 的释放 ,H 的表观释放量能用一级动力学方程和扩散方程拟合 ,Elovich方程不宜拟合pH 5 6酸处理的动力学数据 ;酸溶液pH值为 3 5和 2 5时 ,有H 的消耗 ,H 消耗总量看作表观消耗量 ,用一级动力学方程、Elovich方程和扩散方程进行拟合 .比较相关系数和标准误差的大小 ,除pH值为 2 5的酸处理用扩散方程拟合结果较差外 ,这 3种动力学模型进行拟合均得到较满意的结果

STUDY ON THE KINETIC CHARACTERISTICS OF H+-Ca2+ IN RED SOIL SURFACE UNDER ACID DEPOSITION

The kinetic characteristics of H Ca 2 in red soil surface were investigated under acid deposition by using made design flow stirred device.The results showed that the adsorption of Ca 2 was adequately described by an apparent first order kinetics and parabolic diffusion and Elovich equations( R 2>0 97).The maximal amount of Ca 2 adsorption fitted by the first order equation and diffusion rate conatant( b value)of Ca 2 adsorption fitted by parabolic diffusion equation remarkably decreased with the increase of solution acidity.It could be speculated that the rate controlling step in the adsorption of Ca 2 was the diffusion of ions into the intraparticle space of solid phase.The pH values of effluent were close to the pH value of influent solution with the change of time.The pH values of effuent were lower than that of pH 4 5 and pH 5 6 of influent,and higher that of pH 3 5 and pH 2 5.It showed that the former released H and the latter consumed H .The apparent release amount of H could be fitted by the first order and parabolic diffusion equations,and the kinetic data of pH 5 6 influent could be not suitable for Elovich equation.The apparent consumption of H could be well fitted by the first order and Elovich equations,and the parabolic diffusion could very well describe the kinetic data of pH 3 5 of influent and could not fit that of pH 2 5 influent by according to correlative coefficient( R 2)and standard error(SE).