Role of driven approach on the piezoelectric ozonation processes: Comparing ultrasound with hydro-energy as driving forces

Driven approach is vital for evaluating degradation and energy efficiencies of piezocatalysis process. Thus, piezoelectric ozonation processes driven by hydraulic (HPE-O-3) and ultrasonic (UPE-O-3) forces were compared systematically, using BaTiO3 as piezoelectric material for ibuprofen (IBP) degradation. The synergy indexes of HPE-O-3 and UPE-O-3 processes were 4.51 and 5.78, respectively. Besides, UPE-O-3 process (88.84%) achieved better mineralization efficiency than HPE-O-3 process (68.80%) in 90 min. Nevertheless, the energy consumptions of HPE-O-3 process was only 4.01 parts per thousand of UPE-O-3 process. The formation rate and concentration of (OH)-O-center dot (the dominant active species in both processes) in UPE-O-3 process were 2-3 times higher than that in HPE-O-3 process. Notably, piezoelectric potential and current density driven by ultrasound were approximately 47500-fold and 40-fold than those by hydro-energy, respectively. These led to the difference of (OH)-O-center dot paths between HPE-O-3 and UPE-O-3 processes. Further analyses indicated that *OH was mainly generated by single-electron transfer without H2O2 generation in HPE-O-3 process, whereas both single- and double-electron transfer (with H2O2 generation) contributed to the production of (OH)-O-center dot in UPE-O-3 process. This study revealed the mechanism of piezoelectric ozonation process with different driven approaches and may provide valuable reference for selection of driven approaches in piezocatalytic study and application.

Automated summary

This study compared the piezoelectric ozonation processes driven by hydraulic and ultrasonic forces, revealing that ultrasound-driven process achieved higher efficiency and generated more active species. Despite that, it consumed less energy, mainly due to the significantly higher piezoelectric potential and current density generated by ultrasound, leading to different paths of active species generation.