Abstract

The removal of Hexavalent Chromium (Cr (VI)) is a challenging task due to its acute toxicity even at low concentration. In the present study, graphene oxide-Fe3O4 composite (Fe3O4-GO) was prepared and utilised for the removal of Cr(VI) from aqueous solution. Batch experiments were conducted to investigate the influence of operating variables. Transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometer (VSM), and point zero charge (pHpzc) were used to characterise the Fe3O4-GO. BET surface area of GO was 254.2 m2/g, but for Fe3O4-GO, it was decreased to 194.6 m2/g. From the experimentation, it was found that the best conditions were presented at 45°C, 0.6 g/L, Fe3O4-GO mass, PH = 2, concentration 10 mg/L, and contact time = 60 min with removal efficiencies above 99. Analyses of Cr(VI) adsorption kinetics exhibited relatively rapid adsorption behaviour and obedience of the data from pseudo-second-order kinetics. The Langmuir model resulted in best fits to the adsorption isotherms for both linear and nonlinear models with maximum adsorption of 140.8 mg/g. The adsorption of Cr(VI) was an endothermic and spontaneous process. The removal efficiencies exhibited a moderate reduction in the maximum values (less than 6) after six regeneration cycles. The Fe3O4-GO composite could be a promising material for the removal of Cr(VI) from wastewater. © 2021 Informa UK Limited, trading as Taylor & Francis Group.