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

Pulsed discharge plasma (PDP) was adopted to induce WO for synergetic degradation of ciprofloxacin (CIP) in water. WO 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 photocatalysis successfully, and a synergetic effect was established in PDP/WO system. After 60 min treatment time, 0.16 g/L WO increased the CIP removal from 71.3% to 99.6%, with the enhancement of the first-order kinetic constant from 0.020 min to 0.081 min. 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 played the major role for plasma-degradation of CIP degradation, whereas OH and h were conductive to catalytic degrade CIP. WO addition lead to the decline of O 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 possessed excellent catalytic performance as well as good stability.