Decomposition of naproxen by plasma in liquid process with TiO2 photocatslysts and hydrogen peroxide

Naproxen (NPX), one of the representative non-steroidal anti-inflammatory drug (NSAID) ingredients, was decomposed by plasma in liquid process (PiLP). Strongly oxidized species generated in the plasma field of the PiLP, such as OH radicals, were confirmed by optical emission spectroscopy Increasing the operation parameters (pulse width, frequency and applied voltage) of the power supply promoted plasma field generation and OH radical generation, and affected the NPX decomposition rate. Although the NPX decomposition reaction rate was improved by up to 18–30% by adding TiO2 photocatalyst powder and H2O2 to PiLP, but the optimal addition amount should be determined considering the plasma generation and scavenger effects. A decomposition pathway was proposed, in which NPX was mineralized into CO2 and H2O through five intermediates mainly by decarboxylation, demethylation, hydroxylation, and dehydration reactions via hydroxyl radicals. •Using the plasma in liquid process system NPX was effectively decomposed.•Strongly oxidized species generated in the plasma field of PiLP were confirmed by OES.•As plasma operating conditions increase, OH· and decomposition efficiency increase.•Adding TiO2 and H2O2 to the PiLP system increases the decomposition efficiency of NPX.•NPX is mineralized to CO2 and H2O via five intermediates by mainly hydroxyl radicals.