Use of natural clinoptilolite for the removal of lead, copper and zinc in fixed bed column

This work deals with the removal of lead, copper and zinc from aqueous solutions by using natural zeolite (clinoptilolite). Fixed bed experiments were performed, using three different volumetric flow rates of 5, 7 and 10 bed volume/h, under a total normality of 0.01N, at initial pH of 4 and ambient temperature (25 °C). The removal efficiency increased when decreasing the flow rate and the following selectivity series was found: Pb2+ > Zn2+ ≥ Cu2+. Conductivity measurements showed that lead removal follows mainly ion exchange mechanism, while copper and zinc removal follows ion exchange and sorption mechanism as well.