Efficient removal of antibiotic thiamphenicol by pulsed discharge plasma coupled with complex catalysis using graphene-WO3-Fe3O4 nanocomposites.

Pulsed discharge plasma (PDP) induced complex catalysis for synergetic removal of thiamphenicol (TAP) was investigated using graphene-WO3-Fe3O4 nanocomposites. The prepared samples were characterized systematically in view of the structure and morphology, chemical bonding state, optical property, electrochemical property and magnetic property. Based on characterization and TAP degradation, the catalytic performance followed: graphene-WO3-Fe3O4>graphene-WO3>WO3, and the highest removal efficiency and kinetic constant could reached 99.3% and 0.070 min-1, respectively. With increase of catalyst dosage, the removal efficiency firstly enhanced and then declined. Lower pH value was beneficial for TAP degradation. The prepared graphene-WO3-Fe3O4 owed higher stability and lower dissolution rate of iron ion. The rGO-WO3-Fe3O4 could decompose O3 and H2O2 into more ·OH in PDP system. The degradation intermediates were characterized by fluorescence spectrograph, LC-MS and IC. Based on the detected intermediates and discrete Fourier transform (DFT) analysis, degradation pathway of TAP was proposed. Besides, the toxicity of intermediates was predicted. Finally, catalytic degradation mechanism of TAP by PDP with graphene-WO3-Fe3O4 was summarized.