Preparation and characterization of Schiff-base modified Fe3O4 hybrid material and its selective adsorption for aqueous Hg2.

Abstract

A Fe3O4 hybrid material (Fe3O4@SiO2-S2) modified by Schiff-base was prepared by grafting methyl acrylate (MA), ethylenediamine (EDA), and salicylaldehyde (SA) to the prepared magnetic hybrid material (Fe3O4@SiO2-NH2) successively; what's more, the structure was characterized by FTIR, XRD, SEM, TEM, and VSM. The results showed that the Fe3O4@SiO2-S2 has an obvious core-shell structure and a saturation magnetization of 45.9emu/g. Study on the adsorption of aqueous heavy metal ions showed that Fe3O4@SiO2-S2 posed selective adsorption for Hg2+ with the saturated adsorption capacity of 362mg/g (1.12mmol/g), which was superior to Fe3O4@SiO2-NH2, Fe3O4@SiO2-HO-S, and other adsorbents, at the condition of pH = 6, 45℃, the adsorption capacity remained 89% after 5 cycles of adsorption-desorption; what is more, adsorption equilibrium was reached at about 300min, and the adsorption isotherm conformed to the Langmuir isotherm adsorption model; in addition, pseudo-second-order model could be well described the adsorption kinetic process of Fe3O4@SiO2-S2 to Hg2+. The adsorption mechanism demonstrated that the N atoms of Schiff-base were mainly contributed to the adsorption of Hg2+; what is more, the N atom of tertiary amine and the O atoms of hydroxy and carbonyl also help to the adsorption of Hg2+.