Introduction: Cadmium is a heavy metal with high toxicity and is best known as a carcinogen element. For protecting human health and environment it is necessary to remove excess Cadmium from industrial wastewater before discharging it to surface and ground water. In this study the efficiency of Zinc Oxides Nanoparticles in Cadmium removal from aqueous solution was evaluated. Methods: This is a laboratory experimental study. Adsorption tests were performed in a batch reactor in a laboratory scale using zinc oxide nanoparticles and the effect of initial cadmium concentrations, adsorbent dose, pH, and contact time on the removal efficiency was studied. Theresidual cadmium concentration in the solutionwas determined using flame atomic absorption spectroscopy Varian AA20 made in Australia. Finally for designing graphs, we used Excel software. Results: The results indicated that the adsorption process is affected by different parameters such as initial pollutant concentrations, adsorbent dose, pH, and contact time and Cadmiumremoval efficiency increases with increasing adsorbent dose and reaction time and decreases with increasing initial concentration of Cadmium. Therefore, it is observed that by raising the initial Cadmium concentration, the adsorption rate increases. The maximum efficiency of adsorptionin pH=7amounted to 89.6%. Conclusion: It is concluded that Zinc Oxide nanoparticles have proper efficiency in removal of Cadmium from aqueous solutions and can be used in the treatment of wastewater that contains ion Cadmium. However, its efficiency is deeply dependent on ion strength and the interaction of other metals in wastewater.

Keywords: Cadmium, Heavy metals, Adsorption, Nanoparticles

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