Degradation of mefenamic acid from aqueous solutions by the ozonation and O ₃/UV processes

This study used batch ozonation and O ₃/UV (ultraviolet) processes to investigate factors such as pH, ultraviolet, alkalinity, and humic acid that might affect the degradation and mineralization of mefenamic acid (MEF). The results show that ozonation and O ₃/UV processes were efficient in degrading MEF. A decrease of pH could enhance MEF removal by both the ozonation and O ₃/UV processes. Results also show that the presence of humic acid decreased the removal of MEF. In addition, the degradation of MEF could be expressed in a parallel first-order kinetic model, i.e., rapid and slow kinetic regimes, of the ozonation reaction. The simulation results show that both the fraction and rate constant of the rapid reaction increased as the pH value decreased, which is in agreement with the trend of the removal efficiency of MEF. Besides, the O ₃/UV process usually exhibits a higher γ, the ratio of residual MEF concentration through the rapid reaction to the slow reaction, than ozonation within just 10 min, which suggests that the rapid reaction could enhance the efficiency and effectiveness of degradation in the O ₃/UV process.