Ultrasound-assistant activation of peroxydisulfate by BiFeO3 for highly efficient elimination of antibiotic contaminants: Synergistic piezoelectric catalysis/Fenton-like activation mechanism and toxicity assessments of intermediates

Antibiotic pollution has drastically threatened human health and aquatic ecosystem, and current technologies are confronted with inevitable limitations. Herein, we used BiFeO 3 (BFO) as catalyst, and employed an ultrasound-assistant strategy to activate peroxydisulfate (PDS) for degrading antibiotic contaminants. The synthetic conditions including hydrothermal temperature and time were optimized, and the optimal BFO catalyst could completely decompose Tetracycline hydrochloride (TC, 15 mg l -1 ) in 30 min. The degradation rate of the BFO/PDS/US system is 4.76, 3.98 and 7.14 times higher than those of the PDS/US, BFO/US (piezoelectric catalysis) and BFO/PDS (Fenton-like process) systems, implying the synergistic effect. The influence of reaction conditions on the TC removal was investigated, including TC concentration, pH, and inorganic salt. This technology was demonstrated to possess high efficiency for different antibiotics and aquatic environments, and have good cycling durability. Different reactive oxygen species (ROSs), •SO 4 - , •OH, •O 2 - and 1 O 2 , were generated during the activation process. The coexistence of Bi 3+ /Bi 5+ and Fe 2+ /Fe 3+ in BFO was confirmed, and the relative content of Fe 3+ increased after reaction, indicating the cycle process of Fe 2+ /Fe 3+ . Therefore, a synergistic mechanism of piezoelectric catalysis and Fenton-like activation was proposed to explain the ultrasound-assistant PDS activation by BFO for degradation antibiotics. Finally, the intermediates were detected and their possible toxicities were assessed, which proved the treatment could effectively decrease the potential risk of TC wastewater to environment.