Graphene oxide supported filtration of cesium from aqueous systems

Graphene Oxide-Cesium (GO-Cs) composites, in the form of dispersions as well as solid state thin films, were prepared by introducing different concentrations of Cs into aqueous GO dispersions or subphase. Interaction mechanism of Cs with various functional groups of GO and the extent of Cs uptake on GO sheets under different ambient conditions were investigated using FT-IR, Raman, PL and XPS techniques. Cs was noticed to exhibit preferential interaction with hydroxyl groups of GO and furthermore, incorporation of Cs causes significant change in relative ratios of functional groups, inferring a major structural reorganization in the composite sheets. FT-IR and PL studies showed that aged GO samples can accommodate relatively larger quantities of Cs compared to fresh GO sheets, owing to largely available -COOH and free/associated hydroxyl groups in aged GO sheets. Intercalation studies on GO multilayers indicated that extent of Cs uptake on GO layers increases with duration of intercalation as well as quantity of GO available for interaction. Membrane filters of GO were prepared by controlled coating of GO sheets on filter papers and their adsorption and filtration abilities were tested by filtration of aqueous Cs solutions. Aged GO coated membrane filter displayed superior adsorption abilities compared to those coated with fresh GO sheets, which corroborate well with the inferences drawn from the spectroscopic investigations. In the present work, the prepared GO membrane filters showed a maximum Cs adsorption capacity of similar to 148 mg/g.