Synthesis of Graphitic Carbon Nitride and Polypyrrole Nanocomposite (PPy/g-C3N4) as Efficient Photocatalysts for Dibenzothiophene Degradation in Oilfield Produced Wastewater

Abstract

This study focused on the chemical preparation of g-C3N4 and nancomposite of polypyrrole (PPy) g-C3N4 (PPy/g-C3N4) and characterization of structural, electrochemical and optical properties, as well as photocatalytic applicability for the removal of dibenzothiophene (DBT), an emerging organosulfur pollutant from oil field wastewater under exposure to sunlight. Analyses of photocatalyst structure and morphology revealed that the structures of PPy/g-C3N4 photocatalysts contained amorphous PPy nanoparticles that were decorated on the massive 2D sheet-like structure with numerous breakages and pores on the g-C3N4 sheet surface. Optical analyses revealed that the optical band gap values of g-C3N4 and PPy/g-C3N4 photocatalysts were determined to be ~2.64 and ~2.29 eV, respectively. This indicated a decrease in the optical band gap of PPy/g-C3N4 toward g-C3N4, which enhanced the photocatalytic activity of PPy/g-C3N4 in the visible light region. Because of the smaller particle size of PPy decorated on the g-C3N4 sheet-like structure, electrochemical studies revealed that the synergistic effect between PPy and g-C3N4 can effectively improve electrochemical properties and increase electron transfer rate. Photocatalytic removal studies revealed that total DBT treatment was obtained for g-C3N4 and PPy/g-C3N4 nanocomposite after 125 and 90 minutes of sunlight exposure, respectively. These findings reflect the fast photocatalytic treatment rate of DBT in the presence of PPy/g-C3N4 nanocomposite toward g-C3N4 and other reported photocatalysts in the literature. The practical photocatalytic degradation capability of PPy/g-C3N4 nanocomposite was examined for the treatment of real oilfield wastewater and the results showed the effectual photocatalytic performance of PPy/g-C3N4 nanocomposite for the treatment of DBT in genuine oilfield wastewater