Simultaneous cationic Cu (II)‒anionic Sb (III) removal by NH 2 -Fe 3 O 4 -NTA core-shell magnetic nanoparticle sorbents synthesized via a facile one-pot approach.

In this study, a regenerable magnetic core-shell nanoparticles NH2 -Fe3 O4 -NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe3 O4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH2 -Fe3 O4 -NTAII was prepared by multi-step method for comparison. NH2 -Fe3 O4 -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 m2 /g, respectively. The maximum sorption capacities of NH2 -Fe3 O4 -NTA for cationic Cu (II) and anionic Sb (III) were 55.56 and 51.07 mg/L, respectively, which were superior to that of NH2 -Fe3 O4 -NTAII . Based on screening in terms of characterization and metal sorption capacity, NH2 -Fe3 O4 -NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH2 -Fe3 O4 -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 NH2 -Fe3 O4 -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.