Removal of acid dyes from aqueous solutions by bentonite and kaolin

The adsorption of three acid dyes used in the textile industry, namely Bezanyl Yellow, Bezanyl Red and Nylomine Green onto bentonite and kaolin from aqueous solutions were studied. The kinetic equilibrium data show that bentonite fixes more Bezanyl Yellow, Bezanyl Red and Nylomine Green than kaolin. The results also showed that the kinetics of adsorption are best described by a pseudo-second-order expression. Adsorption isotherms of acid dyes onto bentonite and kaolin were determined and correlated with common isotherm equations such as the Langmuir and Freundlich models. The Langmuir model agrees very well with experimental data. The thermodynamic parameters obtained indicate that the adsorption of acid dyes onto bentonite and kaolin was a spontaneous and an exothermic process. To cite this article: B. Benguella, A. Yacouta-Nour, C R. Chimie 12 (2009). (C) 2008 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.