Influence of Inorganic Salts on Cadmium Adsorption By Montmorillonite and Illite in Alkaline Conditions

Cadmium adsorption features by montmorillonite and illite in alkaline conditions and the influence of inorganic salts were studied by experiment. The cadmium adsorption equilibrium time was 6 hours when the pH values in initiative solutions were 9, and the adsorption cadmium capacity by montmorillonite and illite was 6.910 mg.g
^-1
and 6.642 mg.g
^-1
. When there are inorganic salts in the solutions of which the pH values in initiative solutions were 9, cadmium adsorption capacity by montmorillonite and illite changed pronouncedly. Taking chloride for example, the orders of cations influencing on cadmium adsorption effect were NH
₄

⁺
>Ca
²⁺
>Na
⁺
>K
⁺
>Mg
²⁺
; Taking sodium salt for example, the influence of anions in alkaline conditions were complicated: Cl
^-
, NO
₃

^-
decreased cadmium adsorption capacity while CO
₃

^2-
, H
₂
PO
₄

^-
, HSO
₄

^2-
increased adsorption cadmium capacity by precipitation adsorption.