Abstract
Pillared clays are excellent candidates for adsorption of transition metal ions because of the presence of an ultra dispersed oxyhydroxide phase between the clay layers. On the basis of both macroic (adsorption at variable pHs and the speciation of Cu (II) complexes) and microscopic (ESR of Cu (II) data, we propose a model of adsorption of Cu (II))([Cu (NO3)2] =10-2 mol L-1) from aqueous ammoniacal solution ([NH3]-1-[NH4+] =1mol L-1) on a pillared saponite by hydroxyalum polycations. When the concentration of NH4+ is high, it seems that the Cu (OH) 2aq, Cu (OH) + and Cu2 (OH) 22+ complexes have more affinity for adsorption than [Cu (NH3) n (H2O) 6-n] 2+. On the other hand when the pH is above 9 the concentrations of NH4+ and of the hydroxo copper complexes are very low and the majority adsorbed form becomes [Cu (NH3) 4 (H2O)2] 2+.
