Metal Oxide Nano-particles as an Adsorbent for Removal of Heavy Metals

Abstract

In this study, adsorption process performance was assessed using metal oxide nano particles for wastewater treatment containing heavy metals in a laboratory scale reactor. Copper oxide nano-particles were prepared and fully characterized considering their adsorption properties (surface area and pore size distribution) as well as their chemical structure and morphology. The adsorption of heavy metals, including Fe3+ and Cd2+ was studied in batch experiments. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied. The adsorption of Cd2+ and Fe3+ ions increased with an increase in pH. The optimum solution pH for adsorption of both metals from aqueous solutions was 6. Adsorption was rapid and occurred within the first 20 min for both metals within different solution concentrations (250, 100, 50 and 25 mg/L). The kinetic of Cd2+ and Fe3+ adsorption onto copper oxide nano particles was well fitted by the pseudosecond- order rate equation. The equilibrium adsorption data for Cd2+ was best fitted by the Langmuir adsorption isotherm model, but for Fe3+ adsorption, it was found that Freundlich adsorption isotherm model is the best model to describe it. The selectivity order of the adsorbent is Fe3+>Cd2+. From these results, it can be concluded that the CuO nano particles is a promising adsorbent for the removal of heavy metals from aqueous solutions.