Facile Fabrication Of Magnetic Chitosan Beads For Copper Removal

Heavy metal pollution in water has caused serious influence on human health, ecological environment, and economic development. Regulations on heavy metal in China are becoming more and more stringent. Magnetic chitosan materials are now available for heavy metal sequestration. However, the preparation of material was generally complicated, and the adsorption equilibrium time was still far from satisfaction, which greatly limit their application in water treatment.Here magnetic chitosan (CS) beads of ～200 nm in diameter were successfully prepared by a facile one-step method for Cu(Ⅱ) removal. The resultant composite Fe3O4-CS was characterized with high-resolution transmission electron microscopy (TEM), Dynamic light scattering (DLS), X-ray powder diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), and vibrating-sample magnetometer (VSM). Its adsorption toward Cu(Ⅱ) ions was investigated as a function of solution pH, CS dosage, Cu(Ⅱ) concentration, contact time, and coexisting anions. The maximum capacity of Fe3O4-CS was 129.6 mg Cu(Ⅱ)/g beads (i.e.,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-oriented adsorbents. Continuous adsorption-desorption cycle results demonstrated that Cu(Ⅱ)-load Fe3O4-CS can effectively regenerated by Na2EDTA 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 (MF<0.035 T). The above results can provide reference for the development and application of magnetic chitosan in heavy metal removal.