Pulsed discharge plasma induced WO3 catalysis for synergetic degradation of ciprofloxacin in water: Synergetic mechanism and degradation pathway

Pulsed discharge plasma (PDP) was adopted to induce WO 3 for synergetic degradation of ciprofloxacin (CIP) in water. WO 3 was firstly characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), Photocurrents and Photoluminescence . The degradation results showed that PDP could induce WO 3 photocatalysis successfully, and a synergetic effect was established in PDP/WO 3 system. After 60 min treatment time, 0.16 g/L WO 3 increased the CIP removal from 71.3% to 99.6%, with the enhancement of the first-order kinetic constant from 0.020 min −1 to 0.081 min −1 . Then, the effect of peak voltage, air flow rate and pH on CIP removal was evaluated. Active species trapping test verified that ·OH and ·O 2 − played the major role for plasma-degradation of CIP degradation, whereas OH and h + were conductive to catalytic degrade CIP. WO 3 addition lead to the decline of O 3 and enhancement of OH no matter in deionized water or CIP solution. The degradation process was explored using fluorescence spectrograph , liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC). Finally, the possible degradation pathways of CIP degradation were proposed. The reuse test suggested WO 3 possessed excellent catalytic performance as well as good stability.