Search

The rapidly increasing and widespread use of graphene oxide (GO) as catalyst supports, requires further understanding of its chemical stability in advanced oxidation processes (AOPs). In this study, UV/H 2 O 2 and UV/persulfate (UV/PS) processes were selected to test the chemical instability of GO in terms of their performance in producing highly reactive hydroxyl radicals ( OH) and sulfate radicals (SO 4 − ), respectively. The degradation intermediates were characterized using UV–visible absorption spectra (UV–vis), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Experimental data indicate that UV/PS process was more effective in enhancing GO degradation than the UV/H 2 O 2 system. The overall oxygen-containing functionalities (e.g. C O, C O and O C O groups) dramatically declined. After radical attack, sheet-like GO was destructed into lots of flakes and some low-molecular-weight molecules were detected. The results suggest GO is most vulnerable against SO 4 − radical attack, which deserves special attention while GO acts as a catalyst support or even as a catalyst itself. Therefore, stability of GO and its derivatives should be carefully assessed before they are applied to SO 4 − -based AOPs. [ABSTRACT FROM AUTHOR]