The paper discusses the application of natural zeolites from clinoptilolite group for mercury removal from industrial effluents
from copper smelter and refinery. The experiments included studies on sorption mechanisms (adsorption or ion-exchange) and
sorption equilibria. The dominating mechanism of sorption with zeolite was found to be ion exchange and the maximum sorption
capacity was evaluated as 1.21 meq/g sorbent. Three cation-exchange groups were identified and deprotonation acidity constants
(pKa) 3.1, 7.3 and 10.7 were determined.