X-RAY PHOTOELECTRON SPECTROSCOPIC ANALYSIS OF HALLOYSITES WITH DIFFERENT COMPOSITION AND PARTICLE MORPHOLOGY

摘要: The surface composition of some halloysites with different particle morphology has been investigated by X-ray photoelectron spectroscopy (XPS) before and after removal external Fe. Fe(III) 2 p 3/2 binding energy Fe is appreciably smaller than that structural Particle influenced content. long-tubular halloysite very little Fe, its concentration tends to increase the proportion non-tubular particles in samples. spheroidal sample contains most which, however, does not appear influence shape directly. Study XPS indicates substitutes for Al octahedral positions approximately 1 : proportion. As a result, an vacancies cation exchange capacity would be predicted. Further, layers within crystal are generally inhomogeneous composition. Built up like “onion skins”, either enriched or depleted depending on chemical environment which growth occurs.