酸性条件下可变电荷土壤对锌的吸附动力学特征  

KINETICS OF Zn ADSORPTION BY SELECTED VARIABLE CHARGE SOILS UNDER ACIDIC CONDITIONS

作　　者：王代长[1,2] 孙志成[2] 蒋新[2] 饶伟[1] 李士勇[1] 

机构地区：[1]河南农业大学资源与环境学院,河南省高校农业资源与环境工程技术研究中心,郑州450002 [2]中国科学院南京土壤研究所,南京210008

出　　处：《环境化学》2010年第3期397-401,共5页Environmental Chemistry

基　　金：土壤与农业可持续发展国家重点实验室开放基金(0751010004);国家杰出青年科学基金(40325001);河南农业大学博士基金(30200165,2006-CX-017)

摘　　要：用自行设计的动力学装置,研究了酸性条件下Zn在可变电荷土壤表面的反应动力学吸附特征.结果表明,在酸性条件下,Zn吸附过程分快反应和慢反应.从一级动力学方程拟合的参数可知,土壤的最大吸附量依次为砖红壤>赤红壤>红壤,表观最大吸附量随酸度增加显著下降,砖红壤、赤红壤和红壤在流入液pH5.5时Zn的吸附量为2.81、2.72和1.83mmol.kg-1;pH3.3时为1.0、0.38和0.12mmol.kg-1.用Elovich方程和抛物线扩散方程常数b值,解释离子的表观扩散速率,三种土壤的b值依次为砖红壤>赤红壤>红壤,且随酸度的增大而降低.在Zn吸附过程中,pH5.5时,三种土壤流出液中有质子释放;当原液pH值为4.3、3.8和3.3时,都存在质子的消耗.砖红壤上快速消耗H+量远远大于红壤和赤红壤.反应初期,H+质子的消耗是快速反应,主要包括土壤交换阳离子的缓冲作用、土壤表面的质子化及硫酸专性吸附释放的羟基中和H+质子.The reaction kinetics of Zn adsorption by three variable charge soils under acidic conditions were investigated by using a home-made dynamic device.Results showed that Zn adsorption could be divided into rapid and slow phase.The amount of Zn adsorption was fitted by the first order equation and is in the order of LatosolLatosolic red soilRed soil.Adsorption decreased with increase in acidity.The maximal amounts of Zn adsorption were 2.81,2.72 and 1.83 mmol·kg-1 with pH5.5 effluent and 1.0,0.38 and 0.12 mmol·kg-1 with pH3.3 effluent in Latosol and Latosolic red soil and Red soil.The apparent diffusion rate of ions was rationalized by the b values of Elovich equation and parabolic diffusion equation.The b values are in the order of LatosolLatosolic red soilRed soil,and decreased with increase in acidity.In the process of Zn adsorption,the pH value of the effluent became lower than the pH 5.5 effluent,but higher than the pH 4.3,pH 3.8 and pH 3.3 effluent.The amount of H＋ consumption in Latosol was bigger than that in Latosolic red soil and Red soil.At the initial stage,H＋ consumption was the rapid reaction,which caused by cation exchange,specific adsorption of SO2-4 to release OH-for neutralizing H＋ in the solution,and surface protonation of soil minerals.

关 键 词：土壤酸化 可变电荷土壤 表面反应动力学 锌离子 

分 类 号：X131.3[环境科学与工程—环境科学]