Facile Fabrication of Magnetic Chitosan Beads of Fast Kinetics and High Capacity for Copper Removal

In this study, magnetic chitosan (CS) beads of ∼200 nm in diameter were successfully prepared by a facile one-step method. The resultant composite Fe3O4-CS was characterized using transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Its adsorption toward Cu(II) ions was investigated as a function of solution pH, CS dosage, Cu(II) concentration, and contact time. The maximum capacity of Fe3O4-CS was 129.6 mg of Cu(II)/g of beads (617.1 mg/g of CS). More attractively, the adsorption equilibrium could be achieved within 10 min, which showed superior properties among the available CS-based adsorbents. Continuous adsorption-desorption cyclic results demonstrated that Cu(II)-loaded Fe3O4-CS can be effectively regenerated by ethylenediaminetetraacetic acid (EDTA) solution, and the regenerated composite beads could be employed for repeated use without significant capacity loss. Additionally, Fe3O4-CS beads can be readily separated from water within 30 s under a low magnetic field (<0.035 T).