锌(Ⅱ)、镉(Ⅱ)在伊利石上的吸附及解吸特征研究

研究了Zn²⁺和Cd²⁺在伊利石上的吸附、竞争吸附及其解吸特征，以及初始pH、可溶性腐殖酸与温度对吸附的影响。金属离子的吸附量随初始pH的升高而增大,随温度升高而减小。可溶性腐殖酸的存在可以增加金属离子的吸附量。腐殖酸的浓度越高,金属离子的吸附量增加越多。无论是单组分吸附还是竞争吸附的的吸附量次序都是: Zn²⁺Cd²⁺吸附动力学实验表明Zn²⁺和Cd²⁺在伊利石上的吸附符合伪二级吸附速率模型。计算得到Zn²⁺和Cd²⁺在伊利石上吸附的Ea分别为4104和3915 kJ／mol,表明吸附过程以物理吸附为主。吸附在伊利石上的Cd²⁺和Cd²⁺在水、HCl、NaOH和NaCl中的解吸量的关系是:HCl>NaCl>NaOH> H₂O。

Adsorption and desorption of zinc (Ⅱ) and cadmium(Ⅱ)on illite

Adsorption,competitive adsorption and desorption of zinc(Ⅱ),cadmium(Ⅱ) on illite were studied,and the effects of initial pH,humic acid and temperature were also determined.The adsorption capacities of themetal ions increased with in itial pHincreasing,and decreased with temperature increasing.The adsorption capacities were increased more with increasing concentra-tion of humic acid.Both single-component and competitive adsorption,the order of the adsorption capacities was;Zn~(2+)>Cd~(2+).The results showed that the adsorption process accorded with the pseudo second-order equation.The calculated activation energy of Zn~(2+) and Cd~(2+) on illite were 41.04kJ/mol and 39.15 kJ/mol,which indicated that the adsorption process belongs to physical adsorption.The desorption capacities of Zn~(2+) and Cd~(2+) adsorbed by illite in different solutions were in the following order,HCl>NaCl>NaOH>H_2O.