Heterogeneous irradiation system: enhanced degradation of methylene blue by electron beam irradiation combined with graphite carbon nitride/carbon nanodots.

In the present work, the degradation of methylene blue (MB) was investigated by electron beam irradiation combined with graphite carbon nitride/carbon nanodots (EBI&g-C 3 N 4 /CDs). In comparison with EBI alone, the EBI&g-C 3 N 4 /CDs method showed a higher removal efficiency of high concentrations of MB (500 mg L -1 ) from aqueous solution. Investigation on the effect of the synthesized g-C 3 N 4 /CDs revealed that CDs and g-C 3 N 4 were both contributing factors, while the latter could enhance the degradation of MB through surface reactions that occurred after adsorption. Experiments on the existence of hydrogen peroxide revealed the synergistic effect between g-C 3 N 4 /CDs and hydrogen peroxide. An excellent degradation effect was obtained at natural pH, and the total organic carbon was significantly reduced. Regeneration experiments revealed that the g-C 3 N 4 /CDs material has good stability and reusability. The studies in the presence of assorted radical scavengers suggested that ·OH played a vital role in the degradation process and a total of 17 intermediates were detected using liquid chromatograph-mass spectrometer (LC-MS) analysis. The possible degradation mechanisms of MB were proposed.