title: Adsorption of PolyCarboxylate Poly(ethylene glycol) (PCP) esters on Montmorillonite (Mmt): effect of exchangeable cations (Na+, Mg2+ and Ca2+) and PCP molecular structure.
abstract: This study deals with the adsorption of PolyCarboxylate Poly(ethylene glycol) esters (PCP) superplasticizers on Na-, Mg- and Ca-saturated Montmorillonite (Mmt) clays. The interactions have been examined through different experimental methods: adsorption isotherms, zeta potential measurements and sedimentation experiments. It was found that PCP adsorption depends both on the architecture of PCP molecules and the nature of cation located on the interlayer exchange sites of the Montmorillonite. Whatever the PCP, a larger amount was adsorbed on Na-Mont than on Mg-Mont or Ca-Mont. This indicates the occurrence of two adsorption mechanisms: (i) a superficial adsorption via electrostatic interactions between the carboxylate groups of PCP and positively charged sites on clay surfaces, (ii) intercalation of ether units of the PCP grafts in the interlayer space by displacement of water molecules coordinated to the exchangeable cations. Furthermore, despite the weak negative values of the zeta potential, the addition of PCP promotes the stability of the suspensions which is attributed to steric repulsion acting between particles.
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171 Aubière, France.
authors.forename: Rachid
authors.initials: R
authors.lastname: Ait-Akbour
authors.affiliation: CNRS, UMR 6296, ICCF, F-63171 Aubière, France; CHRYSO, 7 rue de l'Europe, F-45300 Sermaises, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Boustingorry
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171 Aubière, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Leroux
authors.affiliation: CNRS, UMR 6296, ICCF, F-63171 Aubière, France; CHRYSO, 7 rue de l'Europe, F-45300 Sermaises, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Leising
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171 Aubière, France. Electronic address: Christine.TAVIOT-GUEHO@univ-bpclermont.fr.
authors.forename: Christine
authors.initials: C
authors.lastname: Taviot-Guého
keywords: Adsorption; Montmorillonite; PolyCarboxylate Poly(ethylene glycol) esters; Sedimentation; Smectite; Superplasticizers; Zeta potential