Adsorption of Trivalent Antimony from Aqueous Solution Using Graphene Oxide: Kinetic and Thermodynamic Studies

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 (ΔH, ΔS, and ΔG) were evaluated, and the results indicated that t...