Synergistic Adsorption by Biomassbased Fe-Al(Hydr)oxide Nanocomposite of Fluoride and Arsenic

Fe-Al(hydr)oxide nano-/micro-particles were well grown and dispersed on a wheat straw template,which was characterized by a scanning electron microscope(SEM)with energy-dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),and a vibrating sample magnetometer(VSM).The adsorption mechanism of the biomass-based Fe-Al(hydr)oxide nanocomposite was studied by the adsorption isotherms,which followed the Langmuir model better than the Freundlich and Temkin models.In particular,a synergistic adsorption by the mixed Fe-Al(hydr)oxide nano-/micro-particles based on the wheat straw was found,with higher maximum adsorption capacity(Q0)than that of the material containing only Fe3O4 or Al(OH)3 nano-/micro-particles,which was most obvious when the mole ratio of Fe to Al was 1:1.The degree of this unusual effect was reasonably determined by the departure between the experimental and calculated maximum adsorption capacity(Q0-Q0(cal)),which showed that the synergistic effect was most pronounced when the mole ratio of Fe to Al was approximately 1:1.The good adsorption capacity of the mixed Fe-Al(hydr)oxide nano-/micro-particles and the good dispersity by the wheat straw matrix were combined in the biomass-based Fe-Al(hydr)oxide nanocomposite.The nanocomposite material showed high adsorption capacity for both fluoride(F-)and arsenic(As(III)and As(V)),and had the advantage of magnetic separation by tuning its compositions.