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

This study focused on the chemical preparation of g-C 3 N 4 and nancomposite of polypyrrole (PPy) g-C 3 N 4 (PPy/g-C 3 N 4 ) 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-C 3 N 4 photocatalysts contained amorphous PPy nanoparticles that were decorated on the massive 2D sheet-like structure with numerous breakages and pores on the g-C 3 N 4 sheet surface. Optical analyses revealed that the optical band gap values of g-C 3 N 4 and PPy/g-C 3 N 4 photocatalysts were determined to be ∼ 2.64 and ∼ 2.29 eV, respectively. This indicated a decrease in the optical band gap of PPy/g-C 3 N 4 toward g-C 3 N 4 , which enhanced the photocatalytic activity of PPy/g-C 3 N 4 in the visible light region. Because of the smaller particle size of PPy decorated on the g-C 3 N 4 sheet-like structure, electrochemical studies revealed that the synergistic effect between PPy and g-C 3 N 4 can effectively improve electrochemical properties and increase electron transfer rate. Photocatalytic removal studies revealed that total DBT treatment was obtained for g-C 3 N 4 and PPy/g-C 3 N 4 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-C 3 N 4 nanocomposite toward g-C 3 N 4 and other reported photocatalysts in the literature. The practical photocatalytic degradation capability of PPy/g-C 3 N 4 nanocomposite was examined for the treatment of real oilfield wastewater and the results showed the effectual photocatalytic performance of PPy/g-C 3 N 4 nanocomposite for the treatment of DBT in genuine oilfield wastewater.