Effect of core-shell reversal on the structural, magnetic and adsorptive properties of Fe2O3-GO nanocomposites

Abstract

Effect of core-shell reversal on the nanocomposites of graphene oxide (GO) and ferric oxide (Fe2O3) was studied. Fe2O3@GO core-shell nanosheets were synthesized by sonication method, while the GO@Fe2O3 core-shell nanospheres by employing N,N′-dicyclohexylcarbodimide as the binding agent for the wrapping of GO sheets on pre-formed Fe2O3 nanoparticles (NPs). The phase composition, crystallinity and morphology of the nanocomposites were characterized by FT-IR, TEM, SEM-EDS, VSM, BET surface area study and XRD techniques. The saturation magnetization (Ms) was 1.25 and 0.51emug−1 for GO@Fe2O3 and Fe2O3@GO respectively owing to the dependence of magnetic properties on the reversal of core-shell. BET analysis revealed the surface area of 100.32m2g−1 and 45.69m2g−1 for GO@Fe2O3 and Fe2O3@GO nanocomposites respectively. The fabricated nanocomposites were analyzed as adsorbents for the uptake of Pb (II) ions. The impact of various factors affecting adsorption process such as pH, adsorbent dose, contact time, temperature and metal ion concentration was also investigated. GO@Fe2O3 core-shell nanospheres showed a higher adsorption capacity for Pb (II) ions as compared to Fe2O3@GO core-shell nanosheet with the maximum adsorption capacities (qm) of 303.0 and 125.0mgg−1 respectively. The equilibrium data was estimated by Freundlich, Langmuir, D-R and Temkin isotherm models. Thermodynamic analysis confirmed the spontaneous and exothermic nature of the adsorption process. The adsorption kinetics was significantly fitted to pseudo-second order model. The results confirmed that core-shell reversal can significantly alter the adsorptive properties of Fe2O3-GO nanocomposite