Background and objective: The industrial wastewaters are considered to be one of the main sources of heavy metal impurities. The removal of toxic heavy metals from wastewaters is of great importance from an environmental point of zn are the most concerning heavy metals in aqueous solutions due their high toxicity in low concentrations and bioaccumulation in live tissues. Among various removal methods, adsorption through inexpensive adsorbents has been highly considered by researchers. The zn removal by natural clinoptilolite zeolite was defined as the main purpose of the current study.

Methods: The experiments were carried out in batch mode operation with natural zeolite. The zeolite characteristics were analyzed with SEM and XRD. The effect of pH (5, 6, 7, 8, 10), contact time (15, 30, 45, 60,90min), adsorbent dosage (1, 3, 5, 7, 10) and pb and zn concentrations (10, 20, 40, 50, 60, 70, 80 and 100 mg/L) on removal efficiency of zn, adsorption isotherms and kinetics were studied in constant temperature.

Results: Based on the findings, optimum conditions of zn removal by natural zeolite, included pH, 7, adsorbent dose of 5g/L and contact time of 30 minutes. The metal removal was decreased along with metal concentration, but the absorption capacity was increased. Of the two studied models, the Langmuir isotherm was better fitted Freundlich for zn (R2=0.98). Also for Zn, the pseudo second order kinetics was consistent with results.

Conclusion: The results of current study indicated that natural clinoptilolite zeolite can be considered as an efficient and cost effective adsorbent for zn removal from aqueous solutions.