Insight into the Mechanism of Ultrasonic Activation of Persulfate for Enhancing the Removal of Tetracycline Hydrochloride

Tetracycline is often used in treating various diseases or infections, which also leads to severe environmental threats due to its toxicity, durability, and low biodegradation. Meanwhile, although ultrasound (US)-assisted activation of persulfate (PS) is a promising technology for water and wastewater treatment, its reaction mechanism is still not well-defined. Herein, we explored the effect of the enhanced mechanism of ultrasonic activation of peroxymonosulfate (PMS) on the degradation of tetracycline hydrochloride (TCH). The findings revealed that the US/PMS system was highly effective in degrading TCH, achieving an 83.2% degradation efficiency for a TCH concentration of 10 mg/L within 3 h. Moreover, the combination of radical quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed the generation of different types of reactive radicals (such as sulfate radical (SO4 center dot-), hydroxyl radical (center dot OH), superoxide anions (center dot O2-), and singlet oxygen (1O2)) upon PMS activation under ultrasonic cavitation. Thus, US-assisted activation of persulfate is a more promising strategy for efficient removal of refractory organic contaminants in wastewater.