Synthesis and Characterization of Graphene Oxide Under Different Conditions, and a Preliminary Study on its Efficacy to Adsorb Cu2+

Abstract

Graphene oxide (GO) was prepared by the modified Hummer's method, but the mass ratio of graphite to sodium nitrate (NaNO3) was varied from 2:1, 1:1, and 1:2. The primary reason for the variation was to determine the optimum conditions that would afford more oxygen functional groups to improve the material for application in adsorption. The final products, termed GO2:1, GO1:1 and GO1:2, were analyzed by several instrumental techniques. The layered structure of the GO sheet was established by transmission electron microscopy, while powder X-ray diffraction showed that the GO2:1 material was more crystalline than either GO1:1 or GO1:2. Raman spectroscopy revealed the presence of a greater defect density in GO2:1. The presence of oxygen functional groups was verified by Fourier transform infrared spectroscopy, and these were quantified by the Boehm titration method. Overall, GO2:1 had a larger oxygen content than either GO1:1 or GO1:2, and a larger specific surface area. A preliminary study on the adsorption properties of the samples revealed that GO2:1 exhibited the highest percentage removal for Cu 2+ in aqueous solution. Thus, the preparation of graphene oxide with a smaller amount of NaNO3 yielded a material with a greater oxygen content, which showed suitable properties for the adsorption of contaminants in wastewaters.