The promise of coupling piezo-catalysis and activated persulfate using dual-frequency ultrasound: A novel synergistic method of natural water disinfection

Piezo-coupled catalysis, which is driven by dual-frequency ultrasound (DFUS) at high frequencies (>100 kHz), has emerged as a promising technique for intensifying the oxidation processes in aqueous media. This study aimed at evaluating the performance of high-frequency DFUS (0.12 + 1.7 MHz) coupled with ZnO microparticles (1 µm) and persulfate (S₂O₈²⁻) for disinfection of filtered natural surface water, spiked with E. coli and E. faecalis, as well as unfiltered natural water with indigenous microflora. Despite the longer treatment times required (as compared to deionized water), this hybrid system provided the fastest inactivation, exhibiting a synergy between DFUS+ZnO and DFUS+S₂O₈²⁻ processes and a high energy-efficiency (231.5 and 91.3 CFU/J for E. coli and E. faecalis, respectively). The obtained results revealed the feasibility of DFUS-driven piezo-coupled catalysis using persulfate for advanced water disinfection.