Ultrasonic-assisted synthesis of natural clay/Fe3O4/graphene oxide for enhance removal of Cr (VI) from aqueous media.

Abstract

In this study, Fe3O4/graphene oxide (GO)/clay composite was used to remove chromium (VI) ion from aqueous media. The structure and characteristics of the Fe3O4/GO/clay composite were investigated using FT-IR, SEM, EDX/Map, VSM, BET, and XRD analyses. The BET analysis indicated that the specific surface area and mean pore size of the Fe3O4/GO/clay composite were calculated as 61.64 m2/g and 16.2 nm respectively, which indicate that the composite has a mesoporous structure. Also, the VSM analysis showed that the Fe3O4/GO/clay composite has a superparamagnetic property. Moreover, the highest removal efficiency of Cr (VI) from aqueous media was obtained to be 98.84%, which achieved at pH 3, Cr (VI) ion concentration of 10 mg/L, the composite dosage of 1 g/L, contact time of 60 min, and temperature of 25 °C. Furthermore, the kinetic and equilibrium studies showed that the quasi second-order kinetic model and the Langmuir model could better describe the sorption behavior of the clay and the Fe3O4/clay composite, while the behavior of the Fe3O4/GO/clay composite can be better explained by the Freundlich model. Besides, the maximum sorption capacities of the clay, Fe3O4/clay, and Fe3O4/GO/clay composite were obtained to be 49.61, 62.26, and 71.47 mg/g, respectively, which shows that the maximum sorption capacity of the clay increases with improving the surface properties of the clay. Also, the thermodynamic study indicated that the Cr (VI) sorption process was exothermic and spontaneous in nature. In general, the results indicated that the Fe3O4/GO/clay composite was more effective than the clay and the Fe3O4/clay in Cr (VI) ion removal.