Abstract

Results from a laboratory investigation on the capability of activated and modified Bulgarian clinoptilolite samples from Beli plast deposit in Eastern Rhodopes for removing ammonium and phosphates from aqueous solutions are presented in this report. A series of ion exchange batch experiments were carried out using model water composed of NH₄Cl and Na₂HPO₄.12H₂O. Total ion exchange capacity was determined by batch experiments as a function of initial ammonium and phosphates concentration, solution pH and temperature. The influence of the presence of Ca²⁺ on the removal of ammonia was investigated. It was found that the adsorption and ion exchange activity of natural clinoptilolite towards phosphate ions could be increased by chemical activation and modification.

Key words: Clinoptilolite, ammonium, phosphates, ion-exchange, sorption.