Bovine Serum Albumin-Coated Graphene Oxide for Effective Adsorption of Uranium(VI) from Aqueous Solutions

Graphene oxide (GO) was modified by a carbodiimide-induced covalent cross-linking with bovine serum albumin (BSA), enriched with numerous amino and carboxyl functional groups, for radioactive uranium (U-VI) removal. The adsorbent was confirmed through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). We investigated the effect of factors such as the pH, contact time, and initial concentration on the adsorption of U-VI. In this work, the adsorption process closely fitted the Langmuir isotherm model, and pseudo-second-order indicates that chemical adsorption dominates the adsorption process of U-VI onto GO-BSA composites. These results show that the optimal adsorption amount of U-VI of GO-BSA composites was 389 mg g(-1) at 298.15 K, pH = 6, C-0 = 200 mg L-1, and t = 80 min. According to kinetics and the thermodynamic model as well as XPS analysis of pre- and postadsorption of U-VI, we propose that the adsorption behavior of U-VI onto GO-BSA adsorbent is divided into two stages: (1) chelation of the organic functional groups onto the surface of GO-BSA with U-VI; (2) movement of U-VI into the interior of the material after adsorption onto the surface. Moreover, the composites exhibit good adsorption efficiency in simulated seawater, indicating the potential of GO-BSA composites for U-VI removal from seawater.