Functionalized graphene sheets for arsenic removal and desalination of sea water

Water pollution is a major problem in the global context and main cause of some diseases especially in India. Graphene has fascinated the scientific community by its different novel properties for various applications. In the present work, we have synthesized the graphene sheets by hydrogen induced exfoliation of graphitic oxide followed by functionalization. Graphene sheets were characterized by electron microscopy, X-ray diffraction, infra-red and Raman spectroscopy techniques. These functionalized graphene sheets were used for simultaneous removal of high concentration of inorganic species of arsenic (both trivalent and pentavalent) and sodium from aqueous solution using supercapacitor based water filter. In addition, these functionalized graphene sheets based water filter was used for desalination of sea water. Adsorption isotherms and kinetics were studied for the simultaneous removal of sodium and arsenic. Maximum adsorption capacities, using Langmuir isotherm, for arsenate, arsenite and sodium were found to be nearly 142, 139 and 122 mg/g, respectively. High adsorption capacity for both inorganic species of arsenic and sodium along with desalination ability of graphene based supercapacitor provides a solution for commercially feasible water filter.

Research Highlights
► Functionalized graphene, prepared via hydrogen induced exfoliation of graphitic oxide, as supercapacitor electrodes.
► Removal of arsenate and arsenite using the supercapacitor electrodes.
► Functionalization provides better contact between electrodes and water and hence high metal removal.
► High percentage of desalination of sea water using the filter.