Nitrile derivative functionalized graphene oxide membranes for efficient separation of strontium from aqueous waste

Graphene oxide (GO) layers were functionalized with nitrile derivatives through acetonitrile vapour exposure and repercussions of N-functionalization on strontium (Sr(II)) adsorption performance of GO membranes were evaluated. Acetonitrile exposure reduces oxygen content of GO, integrates nitrile (CN), amine (–NH2), multiple highly reactive N-moieties on GO yet, preserves intactness of GO lamellar structures. Nitrile derivative functionalization escalates Sr(II) adsorption ability of GO membranes by nearly two fold and an optimal sorption of ~610 mg/g was obtained at limited GO mass (~0.1 mg) and Sr(II) concentration of 60–100 µg/mL. N-modified GO membranes displayed confinement of ~70% percolated Sr2+ ions, considerable Sr(II) adsorption of ~200 mg/g even after six filtration cycles, limited desorption of 7–24% and competent Sr (II) uptake in presence of Mg2+/Ba2+ ions. Inferences obtained from N-integration and Sr(II) adsorption studies were validated through benzonitrile /nitromethane subjected GO membranes as well, where, adequately amended nitromethane-GO membranes exhibited an enhanced Sr(II) sorption of ~485 mg/g. Pronounced Sr(II) adsorption performances witnessed for variety of N-GO membranes in the present work re-emphasize the eminence of N-groups in Sr(II) capture, efficacy of N-reagent selection, significance of vapour exposure method and demonstrate the potential of N-modified GO membranes in Sr(II) separation.