Spherical polystyrene-supported nano-Fe3O4 of high capacity and low-field separation for arsenate removal from water

Abstract

Fe3O4 is a promising material for arsenic sequestration due to its specific affinity toward arsenic and feasible magnetic separation. How to further increase its adsorption capacity while maintain its low-field separation is an interesting but challenging task. In this study nano-Fe3O4 was successfully coated onto the outer surface of polystyrene (PS) beads of 350–400nm in diameter by the hetero-coacervation method, and the resulting composite PS-Fe3O4 was characterized using transmission electron microscope (TEM), X-ray powder diffraction (XRD), and electrophoresis measurement (EM). Its adsorption toward arsenate was investigated as a function of solution pH, arsenic concentration, contact time, and coexisting anions. The maximum adsorption capacity of PS-Fe3O4 was 139.3mg/g Fe3O4, 77.7% greater than that of bulky Fe3O4. More attractively, it can be readily separated from water under a low magnetic field (<0.035T). Continuous adsorption-desorption cyclic results demonstrated that arsenate-loaded PS-Fe3O4 can be effectively regenerated by NaOH solution, and the regenerated composite beads could be employed for repeated use without significant capacity loss, indicating that nano-Fe3O4 was steadily coated onto the surface of PS beads. Generally, PS beads could be employed as a promising host to fabricate efficient composites originated from Fe3O4 or other nanoparticles for environmental remediation.