Lead (II) adsorption from aqueous systems using visible light activated cobalt doped zinc oxide nanoparticles

Abstract

In this study, co-precipitation method was used to produce cobalt doped zinc oxide (CoZnO) nanoparticles (NPs) by reacting zinc, cobalt and hydroxide (OH− ) in methanol at 60 °C and used as an adsorbent for the removal of lead (Pb) from aqueous systems. Co-ZnO NPs were characterized by X-ray diffraction (XRD) via X-ray Diffractometer (JDX-3532, JEOL, Japan), while Transmission electron microscopy (TEM) was carried out for the shape and size of the NPs. Results shows that Co-ZnO NPs was oval in shape within the size range between 40 to 60 nm. Moreover, the Pb(II) adsorption on Co-ZnO NPs surface was carried out with respect to time, optimum dose, different pH, light effects, filtration and sonication process. The result shows that Co-ZnO NPs can remove Pb(II) efficiently from aqueous systems in the presence of sunlight, optimum dose, neutral pH, and sonication process, while the same NPs could not show effective removal of Pb(II) with respect to darkness, tube light, low and high pH respectively. Using Co-ZnO NPs, Pb(II) can be reduced up to the permissible limit set by World health organization (WHO). CoZnO NPs work effectively in pH range of 5.8–7.2 so therefore, no need to adjust the pH of test solution for the activation of these NPs. The synthesized Co-ZnO NPs are eco-friendly and a capable adsorbent for the removal of Pb(II) from aqueous systems.