Novel Insights on Swelling and Dehydration of Laponite

Author(s)

Valencia, G. A. ^{[1, 2]} ; Djabourov, M. ^[2] ; Carn, F. ^[3] ; Sobral, P. J. A. ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Anim Sci & Food Engn, Dept Food Engn, Pirassununga, SP - Brazil

^[2] PSL Res Univ, ESPCI Paris, Lab Phys Therm, 10 Rue Vauquelin, F-75231 Paris 5 - France

^[3] Univ Parsis Diderot Paris 7, Lab Matiere & Syst Complexes, UMR 7057, Case Courrier 7056, F-75205 Paris 13 - France

• Document type: Journal article
• Source: COLLOID AND INTERFACE SCIENCE COMMUNICATIONS; v. 23, p. 1-5, MAR 2018.
• Web of Science Citations: 2

Abstract

This paper investigates water sorption and dehydration of model synthetic clay (Laponite) and highlights the large differences with natural Na-smectite clays. Measurements were done by combining for the first time thermogravimetric analysis and X-ray diffraction methods on Laponite powders stored in atmospheres with controlled relative humidity. Laponite exhibits a very good reproducibility of the sorption diagram and appears as the most hygroscopic among Na-smectites. The interlayer distance increases from 11 to 20 angstrom when the ratio r = n(H2O)/n(Na) increases from 2 to 22, in agreement with recent numerical simulations. The desorption process, in this range of r, in isothermal conditions follows a first order kinetics with two regimes around r{*} = 7 which is close to the coordination number of Na+ ions in concentrated NaCl solution. Activation energies and frequency factors are derived for the two regimes of desorption and discussed in relation with stability of the cationic complex. (AU)

• FAPESP's process: 12/24047-3 - Physical properties of films based in biopolymers reinforced with laponite
• Grantee: Germán Ayala Valencia
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/07914-8 - FoRC - Food Research Center
• Grantee: Bernadette Dora Gombossy de Melo Franco
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC