Qualitative analysis of heavy metal adsorption by the green synthesized silver nanoparticles,

Abstract

Silver nanoparticles (AgNPs) have attracted high research interest because of their important applications in antimicrobial, cataiysis, and water treatment plants. They dispray totarly new and. errhanced properties compared to larger bulk material particles and these novel properties are due to the difference in specific characteristics such as particle size, distribution, morphology and higher surface area-to-volume ratio. The aim ofthis research was to determine the pb(II) and cu(II) adsorpdon of synthe,;ized AgNps using natural polyrner, chitosan as both reducing and capping agent. AgNPs were formed in an autoclave at 15 pEi and l3I 0c by varying the AgNo, and chitosan concentrations and autoclaving time. AgNPs solution thus obtained was mixed with pbill) and cu(II) (0'05,10,100,200,500ppm)solutionseparatelyand keptovernight. Theremovalofmetarionsfrom the solution was monitored by the shift and intensityvariation ofthe surface plasmon resonance (SpR) band of the AgNPs' The Sreen synthesized silver nanoparticles were characterized using ultra violet vtsible (uV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning erectron microscope (SEM) and particle size anallzer. UV-Vis peak at the 430 nm confirmed the formation of chitosan stabilized silver nanoparticles. The dynamic light scaftering (DLS) measures confirmed that the average size ofsynthesized AgNPs was 818.4 nm with the polydispersity index of0.243 revealing the uniform size and good dispersion ofthe nanoparticles. The optimum concentrations ofAgNo. and chitosan were recorded as 50 mM and 2% respectively. The maximum yield ofnanoparticles was obtained at 60 minutes of autoclaving, which was decided as the optimum time of autoclaving. After addition of meta.l ions, AgNPs solutions showed a color change and a shift and variation in intensity rif the SPR band at lower metal ion concentrations while at higher metnl concentrations SpR band disappeared indicating the adsorption ofmetal ions onto the AgNps. Hence this has the potential to be developed as a heavy metal removal technique in water.