Simultaneous cationic Cu (II)‒anionic Sb (III) removal by NH2-Fe3O4-NTA core-shell magnetic nanoparticle sorbents synthesized via a facile one-pot approach

Abstract In this study, a regenerable magnetic core-shell nanoparticles NH 2 -Fe 3 O 4 -NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe 3 O 4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH 2 -Fe 3 O 4 -NTA II was prepared by multi-step method for comparison. NH 2 -Fe 3 O 4 -NTA had positive zeta potential values of 35.1–0.8 mV at pH 1.8–11.0, with the saturation magnetization and surface area up to 40.56 emu/g and 56.94 m 2 /g, respectively. The maximum sorption capacities of NH 2 -Fe 3 O 4 -NTA for cationic Cu (II) and anionic Sb (III) were 55.56 and 51.07 mg/L, respectively, which were superior to that of NH 2 -Fe 3 O 4 -NTA II . Based on screening in terms of characterization and metal sorption capacity, NH 2 -Fe 3 O 4 -NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH 2 -Fe 3 O 4 -NTA was favored with increasing pH, while the Sb (III) removal preferred low pH (2–3). Simultaneous sorption of Cu (II) and Sb (III) exhibited same removal performance with the sole sorption under high dosage (>1 g/L). In real wastewater applications of NH 2 -Fe 3 O 4 -NTA, multiple metals in actual wastewater could be removed to well below the regulation levels. Nonspecific electrostatic interactions, inner-sphere complexation, ligand exchange, chelation and coordination complexation were responsible for Cu (II) and Sb (III) removal.