Abstract
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.
Highlights
Worldwide developments, population growth, and industrialization have caused the accumulation of P b2+ to the formation of enormous volumes of wastes and environmentalChemical treatment, ion exchange, precipitation, filtration, oxidation–reduction, electrochemical recovery, ultrafiltration, reverse osmosis, electrodialysis, and adsorption are being used to remove such metals from water resources (Mier et al 2001)
It was concluded that the rates of Pb2+ removal for initial concentrations were rapid at initial times for synthetic resin (SR) and kept decreasing gradually
The removal efficiency of two adsorbents was increased with increasing initial P b2+ concentrations until 50 mg/L
Summary
Ion exchange, precipitation, filtration, oxidation–reduction, electrochemical recovery, ultrafiltration, reverse osmosis, electrodialysis, and adsorption are being used to remove such metals from water resources (Mier et al 2001). Many of these approaches may be ineffective, too expensive, or not easy to apply in developing countries. Among more than 40 natural zeolites, Clinoptilolite is the most abundant that most often used water and wastewater treatment (Barrera-Diaz et al 2005; Berber-Mendoza et al 2006; Calvo et al 2009; Faghihian et al 1999; Hamidpour et al 2010; Hwang et al 2011; Suh and Kim 2000; Yang et al 2011). Some parameters like the effect of solution pH on Pb2+ adsorption, contact time, the initial concentration of P b2+, adsorbent dosage, particle size of INZ, and adsorption isotherms were studied
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