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Characteristics and electrical conductivity of graphene and graphene oxide for adsorption of cationic dyes from liquids: Kinetic and thermodynamic study

Abstract:

Graphene (G) and Graphene oxide (GO) were employed in the present study for the removal of two toxic cationic dye Basic Red 12 (BR 12) and Basic Red 46 (BR 46), from aqueous solutions. Graphene oxide was synthesized by Hummer-Offeman method, and then characterized by XRD (X-ray diffraction), and FT-IR (Fourier Transform Infrared spectroscopy). The influence of various physico-chemical parameters such as electrical conductivity behaviors, contact time, solution pH, dye concentration and temperature were well investigated and elucidated. The kinetics and thermodynamics of the toxic dye removal process were also investigated; results clearly depicts that the kinetics of the removal of BR 12 and BR 46 using G and GO as adsorbents follows a pseudo-second-order model. G and GO exhibited high-adsorption capacity for BR 12 and BR 46. The dye removal depends on the initial pH of the solution with the maximum uptake occurring at about pH 9. Moreover, the thermodynamic results confirmed that adsorption of dye BR 46 on G and GO were exothermic and adsorption of dye BR 12 on G and GO were endothermic in nature. The electrical conductivity behaviors of the aqueous solution were found to be enhanced by oxidation of graphene.