Removal of Pb2+, CrT, and Hg2+ Ions from Aqueous Solutions Using Amino-Functionalized Magnetic Nanoparticles

In this paper, a circular economy approach with the adsorption and desorption of heavy metal (HM) ions-i.e., lead (Pb2+), chromium (CrT), and mercury (Hg2+)-from aqueous solutions was studied. Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (gamma-Fe2O3@NH2 NPs) from an aqueous solution at pH 4 and 7. For this purpose, gamma-Fe2O3@NH2 NPs were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), specific surface area (BET), transmission electron microscopy (TEM), EDXS, and zeta potential measurements (zeta). The effects of different adsorbent amounts (m(ads) = 20/45/90 mg) and the type of anions (NO3-, Cl-, SO42-) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO3. The results showed improvement of adsorption efficiency for CrT, Pb2+, and Hg2+ ions at pH 7 by 45 mg of g-Fe2O3@NH2 NPs, and the sequence was as follows: CrT > Hg2+ > Pb2+, with adsorption capacities of 90.4 mg/g, 85.6 mg/g, and 83.6 mg/g, respectively. The desorption results showed the possibility for the reuse of gamma-Fe2O3@NH2 NPs with HNO3, as the desorption efficiency was 100% for Hg2+ ions, 96.7% for CrT, and 91.3% for Pb2+.

Automated summary

In this study, a circular economy approach was applied to remove heavy metal ions from aqueous solutions through adsorption and desorption. The amino-functionalized iron oxide magnetic nanoparticles showed high adsorption efficiency and could be reused through nitric acid desorption.