This work deals with the removal of lead, nickel, copper and zinc from aqueous solutions by using natural zeolite (clinoptilolite) from Gördes mines (West Anatolia, Turkey). The mineralogical and chemical properties of the sorption material were carried out by X-ray diffraction, X-ray fluoremetry, scanning electron microscopy, and wet analysis
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+ ≥ Ni2+ ≥ 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.
Contact time, initial solution pH, solid-to-liquid ratio, and initial metal cation concentration were determined as single ion sorption parameters. The silicon/aluminum ratio and the theoretical and equivalent exchange capacities, both in single and mixed solutions, were established. Corresponding adsorption constants and distribution coefficients have been found.