COPPER(II) INTERACTIONS WITH KAOLINITE - FACTORS CONTROLLING ADSORPTION

The adsorption of Cu**2** plus on kaolinite was studied at different ionic strengths following various treatments of the mineral surface in order to evaluate the conditions influencing adsorption. The data indicate a strong preference of the Na** plus exchange form of kaolinite for Cu**2** plus but a weak affinity of the natural kaolinite for Cu**2** plus . Protons are generated by Cu**2** plus adsorption, as result of the exchange of surface protons, and possibly the enhancement of Cu**2** plus hydrolysis at the kaolinite surfaces. The exchange of Na** plus by Cu**2** plus on the kaolinite is not described by the mass-action equation, but can be interpreted in terms of permanent charge sites on the surfaces when the additional factors of Na** plus -H//3O** plus exchange and blockage of sites by Al ions are considered. Refs.