As(V) Removal from Water Using a Novel Magnetic Particle Adsorbent Prepared with Iron-Containing Water Treatment Residuals

Magnetic particle adsorbent (MPA) was prepared using iron-containing sludge by solvothermal process for As(V) removal from the water solution. The magnetic property, structure features, and surface morphology of MPA were characterized by a vibrating-sample magnetometer, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and Brunauner-Emmett-Teller analysis. Laboratory experiments were also conducted to investigate the adsorption capability and adaptability of MPA for As(V) removal in the water. MPA mainly consisted of gamma-Fe2O3, and its saturation magnetization is 16.95 emu/g. It can be simply separated from water just using a simple magnet. It was mesoporous material with rough surface morphology and large specific surface area (238.7 m(2)/g). The Langmuir adsorption isotherm model could better described the As(V) adsorption behavior than the Freundlich model, which indicated that As(V) adsorbed on the surface of MPA appeared a monolayer distribution. Maximum As(V) adsorption capacities at 25, 35, and 45 degrees C were 8.694, 10.050, and 13.400 mg/g, respectively. As(V) adsorption onto MPA was jointly controlled by intraparticle and film diffusion which was revealed by kinetic studies. There was no conspicuous influence on As(V) adsorption in a broad range of pH from 3 to 10. Among the coexisting anions with As(V) in water, PO43-, and SiO32- had obvious suppression on As(V) adsorption, while HCO3-, SO42-, and Cl- had negligible influence.