Adsorption of trivalent antimony from aqueous solution using graphene oxide: Kinetic and thermodynamic studies

Abstract

© 2015 American Chemical Society.Graphene oxide (GO) used as adsorbent to remove trivalent antimony (Sb(III)) from aqueous solution was studied. X-ray diffraction, Fourier transform infrared, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray analysis were adopted to characterize the GO. Batch experiments were conducted to systematically investigate adsorption efficiency and influence of various parameters, such as initial pH, contact time, initial Sb(III) concentration, and temperature. It is found that GO was particularly effective for the adsorption of Sb(III) within a wide pH range of 2.0 to 10.0 under test conditions. Kinetics of the adsorption process was also studied and the pseudo-first-order rate model was found to fit experimental data well with a highest correlation coefficient (R2 > 0.99). The adsorption isotherm data were better modeled with Langmuir isotherms than with Freundlich isotherms. The thermodynamic parameters (?H, ?S, and ?G) were evaluated, and the results indicated that the adsorption process of Sb(III) on the GO was spontaneous and endothermic. In addition, a remarkable Sb(III) desorption efficiency was achieved when 0.1 mol·L-1 EDTA solution was applied to the GO absorbingly exhausted with Sb(III). Further successful experiments of consecutive adsorption-desorption cycles suggest that GO could be a promising adsorbent for removal of Sb from the contaminated solutions.