Migration of Cu ions in Cu montmorillonite heated with and without alkali halides

Abstract--Cu montmorillonite h ated with or without potassium halide was studied by IR and ESR spectroscopy, supplemented byXRD measurements, microprobe and chemical analyses. It appears that on heating Cu montmorillonite, most of the Cu ions migrate into hexagonal cavities and eventually, when dehydroxylation ccurs, into octahedral vacancies. Some Cu ions may penetrate into octahedral vacancies before dehydroxylation. In the presence of potassium halide, deprotonation facilitates penetration ofCu into octahedral vacancies. The presence within the layers of non-exchangeable Cu ions that are inaccessible to water does not necessarily cause the perturbation ofOH bending vibrations conventionally attributed to migration of small cations into the structure. Such perturbation was only observed when the basal spacing was reduced to ~ 9.5,~. Key Words--Cu-montmorillonite, K-halide, IR and ESR spectra