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

A FeO hybrid material (FeO@SiO-S) modified by Schiff-base was prepared by grafting methyl acrylate (MA), ethylenediamine (EDA), and salicylaldehyde (SA) to the prepared magnetic hybrid material (FeO@SiO-NH) successively; what's more, the structure was characterized by FTIR, XRD, SEM, TEM, and VSM. The results showed that the FeO@SiO-S has an obvious core-shell structure and a saturation magnetization of 45.9 emu/g. Study on the adsorption of aqueous heavy metal ions showed that FeO@SiO-S posed selective adsorption for Hg with the saturated adsorption capacity of 362 mg/g (1.12 mmol/g), which was superior to FeO@SiO-NH, FeO@SiO-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 300 min, 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 FeO@SiO-S to Hg. The adsorption mechanism demonstrated that the N atoms of Schiff-base were mainly contributed to the adsorption of Hg; what is more, the N atom of tertiary amine and the O atoms of hydroxy and carbonyl also help to the adsorption of Hg.