Boosting the adsorption capacity and photocatalytic activity of activated carbon by graphene quantum dots and titanium dioxide

This paper is devoted to enhancing the adsorption and photocatalytic efficiency of activated carbon (AC) by formulating new composites with graphene quantum dots (GQDs) prepared from bagasse, followed by embedding titanium dioxide (TiO2) on the surface of GQDs/AC to obtain GQDs-TiO2/AC. Methylene blue (MB) dye was selected as a model dye pollutant which widely used in leather and textile industries. Studies on removing of MB dye using prepared samples included adsorption and photocatalytic runs. Langmuir model fits the adsorption of MB dye by AC, GQDs/AC, and GQDs-TiO2/AC adsorbents with maximum capacities of 215, 285, and 313 mg/g, respectively. The presence of GQDs with and without TiO2 boosted considerably the surface-active sites, as confirmed by FTIR analysis. Photocatalytic runs in presence of H2O2 as an oxidizing agent and GQDs-TiO2/AC were examined using 200, 300, and 400 mg/L of MB dye. The photo-degradation rate of MB dye by GQDs-TiO2/AC was fast, and superior removal efficiencies were reached; 97.6, 87.6, and 85.7 % from these initial concentrations at 30 min, respectively. Hence, this study affirmed that the GQDs-TiO2/AC demonstrates great potential in removing MB dye through adsorption and photo-degradation processes.