Evaluation efficiency of Iranian natural zeolites and synthetic resin to removal of lead ions from aqueous solutions

Heavy metal such as Pb2+ (lead ions) has high toxicity potential, and it can be dangerous for public health and environment. The ion exchange process is one of the methods that can be used for Pb2+ removal from aqueous solutions. The aim of this study was to investigate the removal efficiency of Pb2+ from the synthetic aqueous solutions using Iranian natural zeolite (INZ) (Clinoptilolite) in comparison with a synthetic resin (SR). In this study, the removal of Pb2+ from aqueous solution investigated by INZ and synthetic resin under different experimental conditions. Parameters like initial Pb2+ concentration, contact times, adsorbent dosage, pH and size particles of INZ, and best-fitted isotherm were studied. The results showed that the most removal efficiency of Pb2+ with INZ was obtained at pH 3–5, contact time 15–60 min, adsorbent dosage 20–50 g/L, Pb2+ initial concentration 25 mg/L, and the removal efficiency was increased with decreasing INZ particle size. The high removal of Pb2+ with SR was at pH 4–6, for 25 mg/L initial Pb2+ concentration at 15–60 min and 5–10 g/L SR. Isotherms study with ISOFT software indicates that the Freundlich and Langmuir isotherms expression provides the best fit for Pb2+ sorption by INZ and SR, respectively. This study indicated that for Pb2+ ion removal, the SR was more efficient than INZ for high concentration solutions; however, in low concentration of Pb2+, the removal efficiency was approximately equal.