X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY OF THE EFFECT OF HEATING ON MONTMORILLONITE CONTAINING SODIUM AND POTASSIUM CATIONS

Abstract- The effect of heating on montmorillonites containing exchangeable Naand K has been studied by X-ray photoelectron spectroscopy (XPS). The surface composition ofthe unheated montmorillonite was consistent with the bulk composition, but after the sample recrystallized at 1 100 ~ the surface abundance of Na increased, whereas that of K decreased. Because Na and K were not present in the high-temperature crystalline products, this behavior suggests hat a noncrystalline material separated from the crystalline products. The Na 1 s binding energy and KL23L23 Auger kinetic energy ofmontmorillonite w re comparable with those of Na in typically ionic compound, such as NaC1. These electron energies became smaller and larger, respectively, on heating and approached those of feldspar (albite). The K 2p3/2 binding energy of montmorillonite ncreased slightly on heating. The K 2p3/2 binding energy of heated sample of montmorillonite was also comparable with that of feldspar (orthoclase). These results uggest that Na and K were incorporated into feldspar-like noncrystalline materials