Effects of counter ions of clay platelets on the swelling behavior of nanocomposite gels

► NC gels with monovalent cations showed large swelling and subsequent deswelling. ► Introduction of multivalent cations depressed the swelling-deswelling markedly. ► Intra-clay/cation and inter-clay/cation interactions. ► Reversible absorption/desorption. ► Selective absorption of multivalent cations.