CHANGES THE STRUCTURE AND CAFFEINE ADSORPTION PROPERTY OF CALCINED MONTMORILLONITE

Abstract

Montmorillonite is widely used as a natural adsorbent. It is generally considered that the
adsorption properties of montmorillonite are largely due to its characteristic layer structure. The structure of
montmorillonite changes under different temperature conditions. In this study, changes in the structure of
montmorillonite 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 of
nonionic organic compounds in a water system. The object of this study is to elucidate the mechanism by
which montmorillonite adsorbs nonionic organic compounds. It is confirmed that, without calcination
treatment, adsorption of caffeine on montmorillonite changes its layer structure. Calcination treatment at
above 573 K causes irreversible dehydration in the structure of montmorillonite. Samples of montmorillonite
calcined at 673 K and 873 K show a reduction in the amount of caffeine adsorbed. In addition, calcination
treatment of montmorillonite at 673 K and 873 K causes less intercalation into the layers. These results show
that adsorption of caffeine on montmorillonite without calcination treatment occurs with the intercalation of
caffeine between layers of montmorillonite. On the other hand, montmorillonite calcined at 873 K is
confirmed to adsorb approximately 20 % of caffeine compared to untreated montmorillonite. It suggested the
possibility of the adsorption of caffeine even on the surfaces and end faces of layers of montmorillonite.