Abstract:

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 the metal ions increased with initial pH increasing, and decreased with temperature increasing. The adsorption capacities were increased more with increasing concentration of humic acid. Both singlecomponent and competitive adsorption, the order of the adsorption capacities was: Cd^2+>Cd²⁺The results showed that the adsorption process accorded with the pseudo secondorder equation. The calculated activation energy of Cd²⁺,Cd²⁺ on illite were 4104／mol and 3915／mol, which indicated that the adsorption process belongs to physical adsorption. The desorption capacities of Cd²⁺,Cd²⁺ adsorbed by illite in different solutions were in the following order, HCl>NaCl>NaOH>H₂O.

Key words: zinc; cadmium; illite; adsorption; desorption