STUDY OF THE ADSORPTIVE PROPERTIES OF A PILLARED CLAY TOWARDS CU2+ AND CD2+ AS A FUNCTION OF PH

On the basis of both macroscopic and microscopic data (adsorption isotherms at variable pi-Is, NMR spectroscopy for Cd2+ and EPR for Cu2+), we propose a chemical model of the interface reactions between metal cations and a clay pillared by hydroxyaluminic polycations. The pillars may be considered as an ultradispersed aluminic phase situated between the layers and are responsible for its adsorptive properties, which are similar, but not identical, to those of an alumina surface. The existence of ionisable acid sites on the pillars favors the adsorption of M(2+) cations at pH values inferior to those reported for Al oxides and hydroxides.