Experiments were conducted to investigate the influence of different factors on the adsorption of Zn2+ and Cd2+ ions from aqueous solution onto vermiculite. The ratio of the initial concentration of ions, C-0, to the adsorbent concentration, W-0, was shown to be the key factor determining the equilibrium ion adsorption density, q(e). Subject to the magnitude of C-0/W-0, the value of q(e) could either attain its maximum level, q(m) (the maximum adsorption density), when the solid surface was fully saturated, or approach its critical limit, q(c) (the C-0/W-0 ratio), when the ions in the bulk sol...
