Synthesis of graphene nanosheets from coffee ground waste and its incorporation to mixed-phase TiO2 as photocatalyst in anthracene degradation

Abstract

The increasing level of coffee consumption in Indonesia causes a significant amount of coffee ground waste as landfill, leading to serious environmental problems on account of phenol derivatives and acidic compounds as its constituents. Containing high carbon content, waste coffee ground is a favourable biomass candidate to be converted into carbon-based material, such as graphene nanosheet (GN). Having wide surface area, graphene derivatives can be used to modify surface of many materials, such as TiO2. The aim of this study is to synthesize graphene-modified TiO2 with a mixed anatase:rutile phase (9:1) and to analyse its photocatalytic activity towards the photodegradation of anthracene, in comparison with unmodified TiO2. UV-DRS analysis showed a significant decrease in the band gap of TiO2/GN-A (2.78 eV) compared with TiO2 (3.00 eV), leading to an increase in photocatalytic activity (Kt TiO2 = 7.26 × 10-4 min−1; Kt TiO2/GN-A = 3.43 × 10-3 min−1). All in all, the synthesized photocatalyst materials presented promising potential to be applied as photocatalysts in photodegradation of organic compounds.