Removal of Pb(2+), CrT, and Hg(2+) 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 (Pb(2+)), chromium (CrT), and mercury (Hg(2+))—from aqueous solutions was studied. Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (γ-Fe(2)O(3)@NH(2) NPs) from an aqueous solution at pH 4 and 7. For this purpose, γ-Fe(2)O(3)@NH(2) 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 (ζ). The effects of different adsorbent amounts (m(ads) = 20/45/90 mg) and the type of anions (NO(3)(−), Cl(−), SO(4)(2−)) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO(3). The results showed improvement of adsorption efficiency for CrT, Pb(2+), and Hg(2+) ions at pH 7 by 45 mg of g-Fe(2)O(3)@NH(2) NPs, and the sequence was as follows: CrT > Hg(2+) > Pb(2+), 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 γ-Fe(2)O(3)@NH(2) NPs with HNO(3), as the desorption efficiency was 100% for Hg(2+) ions, 96.7% for CrT, and 91.3% for Pb(2+).