Study of silver adsorption on montmorillonite

Abstract

In this study Ag+ adsorption on Na+-rich montmorillonite (MMT) type Wyoming was studied. Adsorption data were fitted with several common isotherms but the best regression parameters were obtained for Langmuir model. It indicates that Ag+ was adsorbed on the MMT surface forming a monolayer. By adsorption of small amounts of Ag+ enlargement of the specific surface area (SSA) of micro- (r = 0.4-0.5 nm) and mesopores (r = 1.5-3 nm) was found. Intercalation of Ag+ into MMT was observed using X-ray diffraction (XRD). With increasing concentration of the silver nitrate solutions the content of Ag+ in MMT increased and the layered MMT structure gradually collapsed and exfoliated. The MMT samples saturated with Ag+ were treated with the sodium borohydride solutions to produce Ag0. The mean size of the Ag0crystallites of L111 = 8.5(1) nm was estimated. The metal silver nanoparticles are assumed to be located at the layer surface and crystal edges of MMT. ©2008 Sociedade Brasileira de Química.