Unraveling the Degradation Mechanism and Interaction Mechanism of Ofloxacin Based on Reactive Oxygen Species via Electrochemically Activating Peroxymonosulfate

Abstract

Peroxymonosulfate (PMS) as an oxidant has been extensively applied to remove organic pollutants, but the molecular interaction mechanism of PMS and organic pollutants under the electrochemical process remains unclear. This work unraveled the interaction relationship of PMS on ofloxacin (OFN) degradation by PMS-based electrochemical oxidation. The results showed that hydroxyl and sulfate radicals generated from the electrochemical reaction could effectively degrade OFN. Under the electrochemical oxidation process, 100% or 12.1 ± 2.1% of OFN was degraded within 15 min in the presence or absence of PMS, respectively. Quantum chemical calculations and molecular dynamics simulations indicated that the hydrogen bonds and van der Waals force were the primary interaction force between PMS and OFN. Besides, the PMS-OFN binding process was a stable dynamic process, and its stability was dependent on the number of hydrogen bonds generated. The structure-activity relationship suggested that OFN was transformed into short-chain intermediates with lower toxicity within 15 min. Additionally, this electrochemical system for degrading OFN retained excellent reusability and recyclability, affording high oxidation ability during successive cycles. More importantly, this electrochemical process could highly efficiently degrade various organic pollutants (4-chlorophenol, methyl orange, sulfamethoxazole, and perfluorooctanoic acid). This study provided a new possibility for the application of the electrochemical system in large-scale wastewater treatment.