Facile synthesis of carbon nanotubes and cellulose nanofiber incorporated graphene aerogels for selective organic dye adsorption

Abstract

We introduced a facile and economical method to fabricate graphene aerogels (GAs) with controllable structural properties by incorporating carbon nanotubes (CNTs) and carbon nanofibers (CNFs), and its application in organic dye adsorption is demonstrated. The GAs combined with CNTs and CNFs were synthesized by the hydrothermal method. The adsorption capacity of these CNT-CNF-GA (CCGA) towards cationic dyes (rhodamine 6G (R6G) and methylene blue (MB)) and anionic dyes (methyl orange (MO)) was examined. The presence of oxygen functionalities gives an overall negative charge to CCGA, which exhibited a high adsorption capacity for cationic MB and R6G (96.1 mg/g and 79.2 mg/g, respectively) dyes and a relatively low adsorption capacity towards MO (51.6 mg/g). Further, by adjusting the hydrothermal treatment time, the oxygen functional group content and the surface area of CCGA were optimized to improve the adsorption capacity. All these imply that the porosity of GA, chemical and physical interaction of functional groups, overall charge on GA and the dye molecules, and the size of the dye molecules are the main criteria that affect the selective dye adsorption. These CCGAs exhibited a better adsorption capacity as well as good reusability, indicating their potential for practical use as a dye adsorbent.