Mechanism of Amoxicillin Degradation in Water Treated by Atmospheric-Pressure Air Microplasma

Amoxicillin (AMX) is one of the most widely used antibiotic drugs, which plays an effective role in eliminating bacterial and fungal diseases. However, on account of its poor biodegradability, AMX often leads to water pollution. In this study, the AMX in water was oxidized by atmospheric-pressure air microplasma (APAM). The degradation pathway of AMX in aqueous solution was studied at the molecular level by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS). The results show that AMX can be rapidly removed by APAM. Meanwhile, eight intermediate and two final degradation products were detected. The reactivity of the AMX with different active species generated by APAM can be described in the following sequence: hydroxyl radical ( $\cdot $ OH) > hydrogen peroxide (H ₂ O ₂ ) > ozone(O ₃ ). The APAM treatment is a promising way to oxidize AMX in the aqueous solution into CO, CO ₂ , and H ₂ O.