CHANGES THE STRUCTURE AND CAFFEINE ADSORPTION PROPERTY OF CALCINED MONTMORILLONITE

Abstract

Montmorillonite is widely used as a natural adsorbent. It is generally considered that theadsorption properties of montmorillonite are largely due to its characteristic layer structure. The structure ofmontmorillonite changes under different temperature conditions. In this study, changes in the structure ofmontmorillonite with temperature are analyzed using Synchrotron X-Ray Powder Diffraction (SR-XRD).Observations are made on how montmorillonite with a modified structure is affected by the adsorption ofnonionic organic compounds in a water system. The object of this study is to elucidate the mechanism bywhich montmorillonite adsorbs nonionic organic compounds. It is confirmed that, without calcinationtreatment, adsorption of caffeine on montmorillonite changes its layer structure. Calcination treatment atabove 573 K causes irreversible dehydration in the structure of montmorillonite. Samples of montmorillonitecalcined at 673 K and 873 K show a reduction in the amount of caffeine adsorbed. In addition, calcinationtreatment of montmorillonite at 673 K and 873 K causes less intercalation into the layers. These results showthat adsorption of caffeine on montmorillonite without calcination treatment occurs with the intercalation ofcaffeine between layers of montmorillonite. On the other hand, montmorillonite calcined at 873 K isconfirmed to adsorb approximately 20 % of caffeine compared to untreated montmorillonite. It suggested thepossibility of the adsorption of caffeine even on the surfaces and end faces of layers of montmorillonite.