Removal of Chromium and Cadmium Ions from Water Using Graphene Oxide and Sodium Graphene Oxide Nanocomposites

Abstract

Contamination of underground and surface water by industrial and agricultural activities is a great threat to environmental health. Easy and economically cost effectively available technology for removal of these toxic heavy metals from wastewater is therefore required. Traditional methods of heavy metal removal include reverse osmosis, ion exchange mechanism, chemical precipitation, electrochemical treatment techniques, membrane filtration, coagulation, extraction, irradiation and adsorption. Adsorption is the most preferred technique due to its high efficiency and cost. Activated carbon, clay minerals and natural zeolite, chelating materials, metal oxide nanoparticles and carbon nanosheets have been used for adsorption. In this study, graphene oxide nanocomposites were synthesized using modified Hummer’s method. Sodium graphene oxide was prepared by neutralizing graphene oxide using sodium hydroxide and rinsing with HCl. Surface morphology of the nanocomposites were studied using Fourier transform infrared spectrophotometer. Graphene oxide and sodium graphene oxide were used for removal of Cadmium and Chromium ions. Parameters pH, metal ion concentration, mass of the adsorbent required for adsorption and time of adsorption were optimized. Metal ion concentrations were analyzed using Atomic absorption spectrophotometer. Optimum pH for adsorption was found to be pH 6. A concentration of 200 ppm was experimentally chosen as the optimum for the batch experiments. The optimum mass of the nanocomposites was found to be 0.1g. Equilibrium for adsorption was achieved after 60 minutes for the sodium graphene oxide and 90 minutes for the graphene oxide nanocomposites. The experimental data was fit in both Langmuir and Freundlich isotherms. Keywords: Adsorption, industrialization, nanocomposites, optimization, synthesis