Two-dimensional Fe2O3 nanosheets as adsorbent for the removal of Pb(II) from aqueous solution

Abstract

Two dimensional (2D) metal oxide are expected to be better adsorbents for heavy metal ions than their other low dimensional counterparts. In this work, non-layered 2D Fe2O3 nanosheets were synthesized by a simple combustion method and tested for Pb(II) removal from aqueous solution. The 2D Fe2O3 nanosheets exhibited high crystallinity and purity as confirmed by powder x-ray diffraction. As revealed by scanning electron microscope (SEM) and transmission electron microscope (TEM), the nanosheets with lateral size up to hundreds of microns that made it easy to be recollected after water treatment. The results of XRD and TEM indicated that the nanosheets showed preferentially exposedsurfaces of (100), which has strong affinity for Pb(II). The nanosheets exhibited a moderate specific surface area of 12.19 m2/g with a small pore volume of 0.034 mL/g. The nanosheets exhibited excellent adsorption performance for Pb(II) in pH range from 3.0 to 6.0. The adsorption of Pb(II) conformed to the Langmuir isotherm model with the theoretical maximum adsorption capacity of Pb(II) estimated to be 436.83 mg/g. Kinetics study indicated that the adsorption process followed pseudo-second-order kinetics model. Based on the X-ray photoelectron spectroscopy and FTIR results of the nanosheets before and after Pb(II) adsorption, the adsorption of Pb(II) was dominated by the surface complexation and ion exchange of Pb(II) ions with surface hydroxyl groups. Given the low preparation cost and the excellent adsorption capacity, the non-layered 2D Fe2O3 nanosheets holds great potential as adsorbent for Pb(II) removal.