Physicochemical Adsorption and Aggregative Structures of the Organic Cation [C18mim]+ in the Interlayer of Montmorillonite

An organic cation [C18mim]+ formed from [C18mim]Br, a type of ionic liquid, can go into the interlayer of sodium montmorillonite (MMT) through the ion-exchanging reaction. The adsorption state, the adsorption amount, and the aggregative structures of [C18mim]+ in the interlayer of MMT have been investigated by thermogravimetric analysis (TGA), wide-angle X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that there is a maximum chemical adsorption of [C18mim]+ in the interlayer of MMT, but the total amount of adsorbed [C18mim]+ in the interlayer of MMT increases with that of the physical adsorption of [C18mim]+. With an increasing amount of adsorbed [C18mim]+ in the interlayer of MMT, the aggregative structures of [C18mim]+ become more ordered, leading to an obvious increase of the interlayer distance of MMT.