Mechanistic Insights into Radical-Mediated Moxifloxacin Degradation Using Ultrasound-Assisted Persulfate Activation by Iron-Rich Soil

Fluoroquinolones are a major issue in aquatic ecosystems due to their persistence, potential to induce antibiotic resistance, and inability to be effectively removed using conventional treatment methods. Several advanced oxidation processes have been studied for their degradation; however, there is still a lack of knowledge about their degradation mechanisms and the precise roles played by reactive species. In this context, the study investigated the heterogeneous activation of persulfate (PS) to degrade fluoroquinolones (FQs), such as moxifloxacin (MFX), in iron-rich soil (Cat) under ultrasound irradiation (US). The analysis of the soil catalyst revealed the presence of quartz (35%), iron oxides (33%), and alumina (26%) as the predominant constituents of the sample. The mineral phase analysis indicated the presence of magnetite, hematite, and alumina. Then, the outcomes of the specific surface area, micropore volume, and total pore volume were determined to be 19 m2 g−1, 6 m3 g−1 and 9.10 m3 g−1, respectively. The MFX/PS/US/Cat system demonstrated 89% degradation and 56% mineralization after 300 min. However, the optimized concentrations of i-PrOH, t-BuOH, and CHCl3 were 50, 100, and 50 mM, respectively, in order to trap the radicals SO4•−, OH•, and O2•−. The study examined the individual contributions of SO4•−, OH•, and O2•− radicals to the overall process of MFX degradation. The results indicated that SO4•− was the primary radical, with a contribution of 52%, followed by OH• with 43%, and O2•− with 5%. Finally, the investigation revealed that laterite exhibited both good catalytic activity and reusability over several cycles. The development of this new process could stimulate the creation of cost-effective technology for water remediation through the effective removal of fluoroquinolones.