Synthesis and characterization of graphene oxide functionalized with dicarboxylic acids

Abstract

Graphene oxide (GO) has been reported as another kind of membrane material. Although the use of GO in thin film nanocomposites (TFNs) imbues advantages including antibacterial activity, major challenges to this approach include attrition of the GO sheets from the membrane surface and flux reduction where movement between GO sheets is impeded. This study examined the use of dicarboxylic acids for crosslinking GO sheets to prevent attrition and to control the interlayer spacing of GO sheets. GO prepared via the modified Hummers method, was crosslinked using three dicarboxylic acids of varying chain length: Glutaric (C5H8O4), Adipic (C6H10O14) and Pimelic (C7H12O4) acids. The FTIR spectrum revealed a wider and stronger absorption peak of GO near 3430 cm−1, which could be attributed to the stretching vibration peak of –OH. The peak at 1750 cm−1 revealed a stretching vibrations peak of C = O on the carboxyl group of graphite oxide. The esterification reaction largely occurred at the basal surface area and was shown via the disappearance of epoxy and hydroxyl groups being replaced by an amine group. The spatial XRD analysis showed that interlayer spacing between the GO sheets increased in the order: An increase in the molecular chain of the different crosslinker acids resulted in an increase in the interlayer spacing of the functionalized GO from 7.96Á −8.9À, with the diffraction peaks moving to lower angles. SEM images indicated different surface morphology, attributable to the different effects each dicarboxylic acid has on the initial GO formed.