High adsorption selectivity of zeolite X in the binary ionic system of Cu(II) and Zn(II).

Competitive adsorption behavior of Cu(II) and Zn(II) from this binary system by X zeolite was systematically investigated. The kinetic data of Cu(II) and Zn(II) well fitted with pseudo-second order model. In the binary system, Cu(II) exhibits higher affinity and selectivity on X zeolite. Generally, the adsorption capacity of Zn(II) greatly decreased as the initial concentration of Cu(II) increased. On the contrary, the adsorption capacity of Cu(II) increased as the initial concentration of Zn(II) increased. The Langmuir isotherm model can best describe the adsorption isotherms of Cu(II). Furthermore, the competitive adsorption behavior of the X zeolite suggesting that it is endothermic and spontaneous. The physicochemical properties of presently tested X zeolite were characterized before and after adsorption, and the competitive adsorption mechanism was analyzed. It is indicated that the X zeolite synthesized from diatomite could be a promising candidate for separating certain heavy metals from industrial effluent. [ABSTRACT FROM AUTHOR]