An assessment of the effectiveness of natural zeolites for removal of ammonium and zinc from their dilute solutions

Abstract

The adsorption of NH 4 + and Zn 2+ by four Korean zeolite samples which contained clinoptilolite, mordenite or both was measured by adding solutions containing NH 4 +, Zn 2+, or both, each at a concentration ranging from 1 to 7 meq./l. Both single and successive equilibrations of the sample with the solution showed that clinoptilolite and mordenite have a certain number of NH 4 +-selective exchange sites but not Zn 2+-selective exchange sites. The successive equilibrations were useful to assess the effectiveness of zeolite for removal of NH 4 + and Zn 2+. Mordenite and clinoptilolite would adsorb NH 4 + corresponding to 40–45% and 30% of its cation exchange capacity (CEC), respectively, from the solution containing both NH 4 + and Zn 2+ each at 3 meq./l. The corresponding adsorption of Zn 2+ would be 5–10% of the CEC of each mineral.