Application of silver nanoparticles toward Co(II) and Pb(II) ions contaminant removal in groundwater

Abstract

Applications of nanomaterials has recently been of keen interest to researchers. This fascinating drive ensued due to their unique properties such as optical, magnetic, ease of synthesis, large surface area, and tunable surface chemistry and functionalization that are remarkably different from that of the bulk material. In this work, silver nanoparticles were synthesized and characterized using UV–Vis spectroscopy and scanning electron microscopy. The UV–Vis spectra obtained showed absorption peak at 406 nm wavelength and scanning electron microscope reveals an image of size, 20 nm. The efficiency of our nanomaterial was first tested using standard solutions of cobalt and lead. A bathochromic shift in the absorption wavelength from 406 to 445 nm and from 406 to 458 nm for Cobalt(II) and Lead(II), respectively, indicates an adsorption has taken place. Adsorption characteristics of the nanoparticles evaluated at various incubation periods indicates a percent reduction in cobalt(II) from 33.13 to 53.34% and 79.9–92.92% for lead(II) from day 1–14. This indicates high removal efficiency for lead(II) than cobalt(II) in the proof of concept experiment. The results obtained further reveal that metal ion removal from complexes using silver nanoparticles is time-dependent. The effectiveness of our nanomaterial toward metal ion removal from groundwater was tested using inductively coupled plasma optical emission spectroscopy. The results obtained reveal removal efficiencies of 24% for cobalt and 77% for lead. It is important to note that metal ion concentrations reduced as the incubation periods increased. This is in line with the proof of concept experiment using complex solutions of cobalt and lead. Notably, the percent removal of cobalt was quite low compared to proof of concept experiment. These observations suggest a further research into understanding the adsorption characteristics of metal ions to the surface of nanomaterials in aqueous media