title: Surface properties of kaolin and illite suspensions in concentrated calcium hydroxide medium.
abstract: The adsorption behaviour of calcium hydroxide onto illite and kaolin clay minerals was investigated by monitoring with atomic emission spectroscopy and pH measurements the amounts of ions left in solution after exposing clay minerals to calcium hydroxide solutions of various concentrations. Both clay minerals can adsorb calcium and hydroxyl ions. Rather than just considering proton exchanges at the clay mineral surfaces, the adsorption is explained by an approach based on Lewis description of molecules. With this approach, a mechanism for calcium hydroxide adsorption not only at the edges of the clay particles but also onto the faces is proposed. In order to gain a better insight onto the active groups at the surface of the studied clay minerals, adsorption of pyridine and ammonia on illite and kaolin was followed by FTIR spectroscopy. These measurements gave the signature of edges, which are marginally involved in interactions with calcium ions.
authors.affiliation: GEMH-ENSCI Groupe d'Etude des Matériaux Hétérogènes, Ecole Nationale Supérieure de Céramique Industrielle, 47/73 avenue Albert Thomas, 87065 Limoges Cedex, France.
authors.forename: Koffi Léon
authors.initials: KL
authors.lastname: Konan
authors.forename: Claire
authors.initials: C
authors.lastname: Peyratout
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bonnet
authors.forename: Agnès
authors.initials: A
authors.lastname: Smith
authors.forename: Alain
authors.initials: A
authors.lastname: Jacquet
authors.forename: Patrick
authors.initials: P
authors.lastname: Magnoux
authors.forename: Philippe
authors.initials: P
authors.lastname: Ayrault