Ion exchange of ammonium in natural and synthesized zeolites

In this study, zeolite Na-P and Na-Y was prepared by hydrothermal treatment of the Chinese natural clinoptilolite with NaOH. The ion exchange of NH(4)(+) into the three zeolites in the temperature range of 288-333 K was also investigated, and the thermodynamic parameters were calculated. The selectivity sequence for NH(4)(+) entering the sodium form of the three materials was Na-clinoptilolite > Na-Y > Na-P, as indicated by values of Delta G degrees. The results demonstrated that the Si/Al molar ratio of zeolites determined the selectivity for NH(4)(+). (C) 2008 Elsevier B.V. All rights reserved.