Preconcentration of U(vi) ions on few-layered graphene oxide nanosheets from aqueous solutions (vol 41, pg 6182, 2012)

Herein, few-layered graphene oxide nanosheets were synthesized from graphite using amodified Hummers method and were characterized by TEM, AFM, Raman spectroscopy, XPS, FTIRspectroscopy, TG–DTA and acid–base titrations. The prepared few-layered graphene oxide nanosheetswere used as adsorbents for the preconcentration of U(VI) ions from large volumes of aqueous solutions asa function of pH, ionic strength and temperature.

The sorption of U(VI) ions on the graphene oxidenanosheets was strongly dependent on pH and independent of the ionic strength, indicating that thesorption was mainly dominated by inner-sphere surface complexation rather than by outer-sphere surfacecomplexation or ion exchange. The abundant oxygen-containing functional groups on the surfaces of thegraphene oxide nanosheets played an important role in U(VI) sorption. The sorption of U(VI) on grapheneoxide nanosheets increased with an increase in temperature and the thermodynamic parameters calculatedfrom the temperature-dependent sorption isotherms suggested that the sorption of U(VI) on grapheneoxide nanosheets was an endothermic and spontaneous process.