Modeling the surface charging behavior of clays with negative structural charges and layered double hydroxides with positive structural charges.

MARCELO J. AVENA; RICARDO ROJAS; CARLA E. GIACOMELLI; CARLOS PRIMO DE PAULI

San Francisco

Encuentro; 239th ACS National Meeting & Exposition; 2010

American Chemical Society

Montmorillonites and Layered Double Hydroxides (LDHs) are layered materials with structural charges. Whereas montmorillonites carry negative structural charges and behave as cation exchangers, LDHs carry positive structural charges and behave as anion exchangers. The presence of structural charges affects significantly the reactivity of surface groups on these solids, and thus their proton adsorption, ion adsorption and charging behavior are different from that of solids with no structural charges. Relatively simple models of the solid/water interface can explain the reactivity of montmorillonites and LDHs. Models need to consider the presence of an electric potential (negative for montmorillonite and positive for LDHs) in order to fit experimental proton adsorption curves, ion adsorption and zeta potential data.