MODIFICATION OF CLINOPTILOLITE BY LEACHING WITH ORTHOPHOSPHORIC ACID

The most abundant natural zeolite, clinoptilolite, was leached with H3 PO4 and then studied by X-ray fluorescence and diffraction, adsorption of NH3, thermoprogrammed desorption of NH3, Fe-57 Moessbauer and Four ier transform infrared spectroscopies, and by P-31, Al-27 and Si-29 ma gic-angle spinning nuclear magnetic resonance. The material was purifi ed, because 60% of Fe was extracted, and its crystallinity was preserv ed. The zeolite surface was covered by dilute short-chain polyphosphat e species, containing tetrahedral P, octahedral Al and Ca. The Bronste d acidity was modified by dealumination and creation of POH groups.