Thermal Migration Behavior of Na+, Cu2+ and Li+ in Montmorillonite

The main aim of this paper is to study the cation fixation sites in montmorillonite after heating at different temperatures. Montmorillonite was used adsorb cations (Na+, Cu2+ and Li+) solution, montmorillonite-adsorbed were heated temperatures (unheated, 100 °C, 200 °C 300 °C) for 25 h. Subsequently, basal spacing treated monitored by X-ray diffraction (XRD). exchangeable cationic content determined based on an inductively coupled plasma emission spectrometer (ICP-OES). In addition, stretching bending vibration changes OH group Si-O bond detected Fourier transform infrared spectroscopy (FTIR). related sites. XRD data showed that when temperature reached structure adsorbing Li+ ions completely collapsed, but layer Na+ decreased slightly, which indicated more easily able enter crystal structure. ICP-OES results contents Na+, with increase temperature, fixed than Cu2+. FTIR adsorbed a new band appeared 3971 cm−1, may be caused migration into octahedral vacancy form local trioctahedral has large radius; it can only near not tetrahedron/octahedron montmorillonite. number charges carried high dehydration enthalpy hydrated high. When greater mainly entered hexagonal cavity tetrahedron slight vibration. hardly changed peak moved value region Li+, speculated