Abstract
Eco-friendly iron nanoparticles (FeNP) were synthesized by utilizing a natural plant extract as a reducing and stabilizing agent. To further enhance the affinity of the nanoparticles toward heavy metals, N-[3-(Trimethoxysilyl)propyl]ethylenediamine (DA) was attached to the surface of FeNP by two different techniques, namely post-synthesis (grafting) and one-pot synthesis to produce FeNP-DA-G, and FeNP-DA-P, respectively. The three samples were characterized by TEM, SEM, TGA, UV, FT-IR, DLS, and BET analysis. The FT-IR spectra confirmed the capping rule of the plant extract in addition to the existence of the OH groups that are important for the reduction step. The DLS analysis supported the capping effect of the plant extract by showing a much larger particle size distribution than the one obtained by TEM. Both SEM and TEM images indicated irregular shape particles with a tendency to aggregate for FeNP and some larger spherical particles and broader particle size distribution for FeNP-DA-G, while FeNP-DA-P images showed more spherical particles with narrow size distribution and a tendency to aggregation. The successful formation of the nanoparticles was also confirmed via UV spectra, while the successful attachment of the DA to the surface of FeNP-DA-G and FeNP-DA-P was confirmed by EDS analysis. BET analysis showed a drastic decrease in both surface area and pore volume of FeNP-DA-G compared to FeNP and FeNP-DA-P, which is related to the blockage of the pores after attaching DA. The three samples were tested for the adsorption of lead ions from aqueous solutions. Both equilibrium and kinetic properties of the adsorption process were investigated and compared. The results generally suggested that the best sample concerning the removal of lead ions was FeNP-DA-P, followed by FeNP, and finally FeNP-DA-G.