Modification of a Nakhchivan Natural Zeolite in the Alkaline Environment

Abstract

Using a Nakhchivan natural mineral as a base, zeolites of different structural types are synthesized. Natural zeolite is modified under hydrothermal conditions in aqueous solutions of LiOH, KOH, NaOH, and Ca(OH)₂, as well as in the presence of mineralizers (LiCl, KCl, NaCl, CaCl₂) in an autoclave. Based on the data of IR-spectroscopic, X-ray phase, and elemental analyses, it is shown that during the hydrothermal treatment, natural zeolite is transformed into other minerals of the zeolite group that are important in practice. It is found that mordenite retains the structure’s stability in the alkaline solutions with a concentration of 1 N at a temperature of up to 100°C for 10 h. When the conditions of hydrothermal treatment change, natural zeolite gradually transforms into hydrosodalite through the mineral phases: chabazite, heulandite, clinoptilolite, analcime, phillipsite, faujasite, scapolite, zeolite M, gismondine, leucite, and kalsilite. The presence of mineralizers in the environment leads to the production of structural types of zeolites that differ from those obtained in a thermal solution.