Coal-Derived Graphene Oxide/Copper Ferrite Nanocomposites with Antibacterial and Sonophotocatalytic Properties for Wastewater Remediation

As the world population continues to steadily increase, the demand for pure-water has grown, indicating a water scarcity crisis in the near future. Providing safe drinking water is a great challenge for both the developing and the developed world as much of the Earth’s water supply has been immensely contaminated due to human activities, which led to source water quality deterioration. Consuming water contaminated with pathogens put people at risk of illnesses such as cholera and typhoid. Secondly, pesticides, dyes, personal care products and pharmaceuticals are found in various water resources. The conventional wastewater treatment methods use to eliminate organic pollutants showed several limitations, namely low removal efficiencies towards non-biodegradable and refractory pollutant, long removal times, and requirement of post-treatments. Therefore, it is of importance to develop novel methods for wastewater remediation. Nanotechnology holds great promise in ensuring safe drinking water through the development of active nanomaterials and filtration membranes. In this work, coal-derived graphene/copper ferrite nanocomposites were fabricated, characterized and its antibacterial activity and sonophotocatalytic properties were reported.<br/>For the preparation of nanocomposites, coal samples from Tavan Tolgoi coal mine in Umnugovi, Mongolia were grinded, sieved and graphitized to form graphite flakes. Then, graphene oxide was synthesized from the graphite flakes using modified Hummer’s method. Sol-gel synthesis route was opted for the fabrication of graphene oxide/copper ferrite nanocomposite. The optical responses of prepared nanocomposite were analyzed using Ultraviolet-Visible (UV-Vis) spectrophotometer. The structural and elemental compositions were characterized using X-ray diffractometer (XRD) and Fourier-Transform Infrared Spectroscopy (FTIR), zeta potentials were measured using Zetasizer, and the surface morphology was analyzed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Sonophotocatalytic properties of synthesized nanocomposite were tested under visible light irradiation using a bath sonicator and methyl orange as a model compound. Gram negative bacterium <i>E. coli</i> and Gram-positive bacterium <i>S. aureus</i> were chosen as model bacteria to evaluate the antibacterial performance of the nanocomposites. Considering the practical application, a real water sample treatment experiment was investigated to test antibacterial performance. Four water samples were collected from river water, household wastewater, tap water and distilled water and the antibacterial activities of obtained nanocomposites were tested in all four samples.<br/>Graphene oxide/copper ferrite nanocomposite was shown to be an effective sonophotocatalyst for the degradation of methyl orange under visible light irradiation and because it has magnetic property the catalyst can be readily recovered and reused without significant loss of its catalytic activity. Also, the obtained nanocomposites exhibited excellent antibacterial activity against <i>E.coli</i> and <i>S.aureus</i>, and antibacterial performance was also shown in all water samples.