Enhancement of Rb+ and Cs+ removal in 3D carbon aerogel-supported Na2Ti3O7

In this paper, three-dimensional carbon aerogel (CA) combined sodium titanate (CA/Na2Ti3O7) was synthesized via a facile hydrothermal method, which was applied to remove Rb+ and Cs+ from aqueous solution. It is found the CA/Na2Ti3O7 composites have larger adsorption capacity and faster adsorption equilibrium time than that of pure Na2Ti3O7, which is ascribed to the enhanced effect of CA on Na2Ti3O7. The adsorption isotherms can be fitted by the Langmuir model well. The adsorption mechanism at pH < 8.0 is attributed to the ion exchange process, while inner-sphere surface complexation is predominant at pH > 8.0. The adsorption kinetics follows the pseudo-second-order model and the major mechanism is identified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. The adsorption of Rb+ and Cs+ on CA/Na2Ti3O7 can be explained by the ion exchange between Rb+/Cs+ and Na+ in the interlayer of Na2Ti3O7 and the complexation of Rb+/Cs+ with the –OH functional groups of CA/Na2Ti3O7. These results show potential application of CA/Na2Ti3O7 in the elimination of radionuclides from wastewater.