College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, No. 35, Tsinghua East Rd, Beijing, 100083, China. Electronic address: [Email]
In this study, a regenerable magnetic core-shell nanoparticles NH2-Fe3O4-NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe3O4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH2-Fe3O4-NTAII was prepared by multi-step method for comparison. NH2-Fe3O4-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-Fe3O4-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-Fe3O4-NTAII. Based on screening in terms of characterization and metal sorption capacity, NH2-Fe3O4-NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH2-Fe3O4-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-Fe3O4-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.