Nano scale zerovalent nickel: Green synthesis, characterization, and efficient removal of lead from aqueous solution

Lead is one of the toxic heavy metal pollutants and if present in water above its permissible limit can lead to various neurodevelopmental and cardiovascular disorders in human beings. The objective of the present work is removal lead ions from aqueous solution using novel nickel nanoparticles (AONi) prepared by green synthesis from testa extract of Annacardium occidentale which acts as an eco-friendly adsorbent. The physicochemical properties of AONi nanoparticles were characterized through UV-Visible spectroscopy, FTIR analysis, SEM-EDS, XRD, and HR-TEM analysis. The adsorption capacity of AONi nanoparticles and the effect of pH, adsorbent and adsorbate dosage, and contact time are studied by batch experiments and analyzed by Langmuir and Freundlich adsorption isotherm. The correlation coefficient, R-2 = 0.99 is in agreement with Freundlich's multilayer adsorption. The separation factor, R-L of Langmuir isotherm is 0.20, which also indicates favorable adsorption. Kinetic studies further confirm that the adsorption follows a pseudo-second-order mechanism.