Nanocomposite of γ-Fe2O3 immobilized on graphene oxide for remediation of Ni(II) ions - Kinetics, isotherm and thermodynamics studies

Abstract

Facile sonication method was used to immobilize γ-Fe2O3 nanoparticles (NPs) on graphene oxide (GO) to obtain environmentally stable γ-Fe2O3-GO nanocomposite (NC). Structure, surface morphology and composition of NC were thoroughly studied. Mössbauer analysis confirmed the presence of maghemite (γ-Fe2O3) as dominant phase of iron oxide. TEM images of NC revealed homogeneous distribution of γ-Fe2O3 NPs over the GO nanosheet. A comparative analysis of GO, γ-Fe2O3 NPs and NC for the removal of Ni(II) ions from water was carried out by batch method and adsorption kinetics, thermodynamics and isotherms were also studied. The adsorption data fitted better to Langmuir and Freundlich adsorption isotherms as compared to Dubinin Radushkevich (D-R) and Temkin adsorption isotherms. NC showed higher qmax value (615.0 mg/g) as compared to the pristine GO (403.7 mg/g) and γ-Fe2O3 NPs (572.4 mg/g). The adsorption kinetics followed pseudo-second-order model. NC displayed greater affinity for Ni(II) ions in comparison to pristine GO and γ-Fe2O3 NPs. The results suggested that the synthesized γ-Fe2O3-GO nanocomposite can be used as a promising novel material for the removal of Ni(II) from water due to its higher adsorption capacity, stability, convenient magnetic separation and regeneration.