Decontamination of U(VI) on graphene oxide/Al2O3 composites investigated by XRD, FT-IR and XPS techniques.

The decontamination of U(VI) on graphene oxide/nano-alumina (GO/Al2O3) composites were investigated by batch, XRD, FT-IR and XPS techniques. The characterization results showed that GO/Al2O3 composites presented a variety of oxygen-containing functional groups, which provided the more surface reactive sites. The batch experiments indicated that sorption equilibrium of U(VI) on GO/Al2O3 composites was achieved within 30 min, and the maximum sorption capacity derived from Langmuir model was 142.8 mg/g at pH 6.5. In addition, the slight decrease of sorption capacity was observed even after fifth recycling times. These results indicated that GO/Al2O3 composites displayed the fast sorption rate, high sorption capacity and good regeneration performance. No effect of ionic strength revealed the inner-sphere surface complexation of U(VI) on GO/Al2O3 composites. FT-IR and XPS analysis demonstrated that the high adsorption of U(VI) on GO/Al2O3 was attributed to the various oxygen-bearing functional groups. In addition, the nano Al2O3 was transferred to amorphous AlO(OH) mineral phase by XRD pattern, which provided the additional reactive sorption sites. These observations indicated that GO-based composites can be regarded as a promising adsorbent for immobilization and pre-concentration of U(VI) from aqueous solutions in the environmental remediation.