Abstract:
The heavy metals found in contaminated waters were dangerous for the environment and human
health, so it was necessary to seek and apply techniques to remove these pollutants, using adsorption
techniques with green synthesized metal oxide nanoparticles as cost effective adsorbent. Green synthesis
of metal oxide nanoparticles (NPs) was a viable alternative methodology because of cost-effective and
availability of environmentally friendly templates for desired application, which has attracted the
attention of researchers in recent years. Since large amounts of Curcuma longa spice waste were
abandoned after agro-processes around Tepi areas, the possibility of developing value-added products
from them was interesting innovation. In this work, Metal oxide nanoparticles were synthesized by using Curcuma Longa spice peel extract
afterward which were then used as Lead metal ion adsorbents. The Metal oxide ZnO, CuO, and Co3O4
nanoparticles was characterized by several techniques including Fourier transform infrared spectra
(FTIR), scanning electron microscope (SEM-EDX) indicates that the green synthesized metal oxide (ZnO, CuO, and Co3O4) nanoparticles were too crystalline, and thermogravimetric analysis (TGA) metal oxide
nanoparticles indicated that ZnO nanoparticle was more stable than other. Metal oxide nanoparticles
were showed the enhanced antibacterial activity; 13 mm, 11mm, and 13mm towards S. Pyogen for ZnO, Co3O4, and CuO respectively, which was attributed to the formation of enhanced reactive oxygen species
(ROS). This metal oxide nanoparticles were used as adsorbents for adsorption studies of heavy metal ions (Pb
+2)
within batch adsorption systems. From adsorption parameter (pH effect, metal ion conc. effect, contact
time effect, and dosage effect) it was found that the metal oxide (ZnO, CuO, and Co3O4) nanoparticles had
maximum adsorption for Pb
+2 within a given pH rage of 2–10 were 90.5% at the pH 7, 87.52% at pH 5, and 88.63%, at pH 6 for ZnO, CuO, and Co3O4 respectively. In the kinetic model study, a pseudo-second- order model yielded a higher correlation coefficient (R
2) for all metal oxide nanoparticles, than pseudo first-order kinetic model; this describe that well fit of pseudo-second-order model for adsorption
behaviour of Pb
+2 onto metal oxide nanoparticles. Additionally, the adsorption isotherm behaviour for
adsorbate onto adsorbent was well described using the Freundlich isotherm model which shows the
highest correlation coefficient (R
2); since the adsorption behaviour of adsorbents involved multilayer
physisorption in this study. From the results of this investigation, there was countless possibility for the
growth of low-cost adsorbent materials like, ZnO, CuO, and Co3O4
