Optimised activation of bentonite for toluene adsorption

Acid-activation of bentonite was optimised to prepare an effective adsorbent of toluene. The activated bentonite was obtained with a specific surface area of 195 m(2)/g, a pore volume of about 0.46 cm(3)/g and a most frequent pore size of 62 angstrom. Compared to the raw bentonite, the adsorption of toluene onto acid-activated bentonite was increased from 66 mg/g to 197 mg/g. Vapor-solid adsorption isotherms of toluene were measured at 120 degrees C, 140 degrees C, 160 degrees C and 182 degrees C using an inverse gas chromatography. The experimental data were correlated with different adsorption isotherm models such as Langmuir, Freundlich, Langmuir-Freundlich and Toth models. Only the Langmuir-Freundlich equation provided good fit to the experimental data. (C) 2009 Elsevier B.V. All rights reserved.