Removal and Preconcentration of Pb (II) and Cd (II) by Zero-Valent Iron Nanoparticles in Contaminated Water

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Background: Lead (Pb) and cadmium (Cd) are two of the hazardous metals in the environment due to their acute and chronic effects on human health. Zero-valent iron nanoparticles (ZVINPs) are one of the adsorbents proposed as an efficient adsorbent for Pb and Cd. Objectives: This study evaluated the quantitative removal efficiency of Pb and Cd ions from contaminated water by ZVINPs. In addition, the capability of ZVINPs as a solid phase extractor for preconcentration and determination of Pb and Cd was investigated. Materials and Methods: Four samples, each from different water sources like Well water (Shushtar, Iran), Karoon River (Ahvaz, Iran), Caspian Sea (northern Iran) and Persian Gulf (southern Iran) were collected. Results: The elapsed time for quantitative removal of both Pb and Cd ions was two minutes. This method is applicable in a widespread range of pH and relatively high concentrations of electrolyte (NaCl) for the efficient removal (> 99%) of Pb and Cd ions in water samples. The adsorption of Pb and Cd ions on ZVINPs was well followed by the Langmuir model. The maximum adsorption amounts of Pb and Cd ions on ZVINPs were 96.5 and 58.3 mg/g, respectively. Limits of detection (LODs) of the method for lead and cadmium ions were 0.015 and 0.002 mg/L, respectively. The relative standard deviations for ten replicate determinations (Pb2+ 0.3 mg/L, Cd2+ 0.03 mg/L) were below 5%. The enrichment factors were more than 16 and 14 for Pb2+ and Cd2+, respectively. Conclusions: The proposed method is simple, fast, cost-effective and safe for the environment.