Synthesis of CS-Fe3O4/GO nanocomposite for adsorption of heavy metal in aqueous environment

Abstract

In this study, magnetic material based on graphene oxide (GO) was developed for enhanced adsorption capacity for heavy metals. The Fe3O4 nanoparticles were combined with the GO material using a chitosan (CS) binder to obtain the CS-Fe3O4/GO nanocomposite. The adsorption capacity of this nanocomposite was evaluated by removing heavy metals including Ni2+ ions. When GO was composed with Fe3O4 and CS, the GO films were densely covered with ferromagnetic particles, which were bound and densely distributed on the GO film surface due to the interaction between GO and CS. The optimal conditions for the complexation of Ni2+ and 4-(2-pyridyl azo)-rezoxine (PAR) are 1 ml Ni2+, 2 ml PAR 100 mg l−1, pH = 6 (adjusted with 0.7 ml of the 0.1 M K2HPO4 solution) and a complexation time of 20 min. After 50 min of adsorption, the Ni2+ removal efficiency of the CS-Fe3O4/GO nanocomposite reached 81.21% and the corresponding adsorption capacity was 2.03 mg g−1 . The Ni2+ removal process followed the first-order model and Freundlich isotherm. This process was spontaneous (ΔG o < 0) and an exothermic process (ΔH o = −1128.875 J·mol−1). In addition, the factors affecting this process were investigated, including the pH solution, the dosage of the CS-Fe3O4/GO nanocomposite and the initial Ni2+ concentration. The CS-Fe3O4/GO nanocomposite showed a potential adsorption capacity in removing Ni2+ at low concentrations from wastewater.