Effect of water chemistries on adsorption of Cs(I) onto graphene oxide investigated by batch and modeling techniques

Abstract

Effect of water chemistries (i.e., reaction time, pH, ionic strength and temperature) on Cs(I) adsorption on graphene oxide were investigated by batch techniques. The characterized results indicated that graphene oxide synthesized by the modified Hummers method presented a variety of oxygen-containing functional groups such as epoxy, carbonyl, carboxyl and hydroxyl groups. The adsorption kinetics of Cs(I) on graphene oxide can be satisfactorily fitted by pseudo-second-order kinetic model with such high correlation coefficient (R2>0.9999). The adsorption isotherm can be fitted by Langmuir model very well (R2>0.995) compared to Freundlich model (R2<0.985). The maximum adsorption capacity of graphene oxide calculated from Langmuir mode at pH 3.0 and 293K was 40.00mg/g. The thermodynamic parameters showed that the adsorption of Cs(I) on graphene oxide was an exothermal and spontaneous processes. The results of surface complexation modeling indicated that the diffuse layer model can give an excellent fits with SOHCs+ and SOCs(OH)− species, which indicating that adsorption of Cs(I) on graphene oxide was outer- and inner-sphere surface complexation at pH<4.0 and pH>5.0, respectively. The findings presented herein revealed that graphene oxide was a promising adsorbent for the removal and immobilization of radionuclide from aqueous solutions in environmental cleanup.