Enhancement of Phenol degradation, using of novel Z-scheme Bi2WO6/C3N4/TiO2 composite: Catalyst and operational parameters optimization

A novel Z-scheme Bi2WO6/C3N4/TiO2 ternary heterojunction was successfully synthesized by the sol–gel / hydrothermal method. The photocatalytic activity of Bi2WO6/C3N4/TiO2 was investigated by the phenol degradation under simulated sunlight illumination. The Bi2WO6/C3N4/TiO2 ternary Z-scheme involving 30 wt% of TiO2, while Bi2WO6 to C3N4 mass ratio resulted in 65 to 35, was realized as an optimal composite and exhibited the best photocatalytic activity compared with individual g-C3N4, Bi2WO6/C3N4 and Bi2WO6/C3N4/TiO2 with different mass percentage ratios. The optimum amount of operating parameters were determined as: initial phenol concentration = 10 mg/L, pH = 7, catalyst dose = 1.5 g/L and irradiation time = 180 min. The maximum phenol removal efficiency in the presence of Bi2WO6/C3N4/TiO2 reached 84.7% at optimum conditions. The photocatalytic phenol degradation mechanism followed the first-order kinetic and the reaction rate of the ternary photocatalyst was around 2.18 and 1.34 times, higher than those of Bi2WO6 and Bi2WO6 / C3N4, respectively. In addition, all of the OH●, O2– ●, h+, and e- active species efficiently promoted the photocatalytic process. Complete mineralization took a place almost after 7.5 h from the beginning of the phenol photodegradation the synthesized Z-scheme exhibited excellent chemical constancy and reusability next to the five cycles of utilizations.