Hydraulic-driven piezoelectric ozonation process for nitrobenzene degradation: synergy, energy consumption, impact factors, mechanism, and application potential

Abstract

Although ozone coupling with electrolysis (E–O₃) can increase the degradation of refractory organics due to effective generation of the hydroxyl radical (˙OH), its external power supply dependence and relatively high energy consumption restrict its application. Hence, a hydraulic-driven piezoelectric ozonation process (PE-O₃) was proposed for nitrobenzene (NB) degradation. Notably, the synergy index of the PE-O₃ process for NB degradation reached 3.98, while the mineralization ratio approached 85.23% in 120 min. The finite element method (FEM) revealed a positive correlation between the piezoelectric potential and the hydraulic gradient (G). A further study demonstrated that the gratifying degradation of NB was attributed to the massive production of ˙OH. Besides, various refractory organics could be effectively degraded in the PE-O₃ process, while a satisfactory degradation of NB was observed in the actual water matrix. Moreover, the degradation of NB only decreased by 4.60% after 10 cycles of BaTiO₃ without any metal ion leakage in the PE-O₃ process. The energy consumption of the PE-O₃ process for NB degradation was much lower than other ozone-based processes. This study may provide an efficient approach to the degradation of refractory organics by the potential utilization of residual hydraulic power in the water treatment and delivery process.