Efficient removal of bisphenol A by carbon nitride/peroxymonosulfate/solar system: multi-radical association mechanism by the morphology and crystallinity optimization

Two types of carbon nitrides were prepared by a thermal polymerization method with melamine and prefabricated supermolecules as precursors, and then used for the degradation of bisphenol A (BPA) in the presence of peroxymonosulfate (PMS) and simulated sunlight. The results showed that the 20 mg L-1 of BPA can be completely degraded within 40 min using 0.1 g L-1 supramolecular-derived g-C3N4 (SCN) and 1 mM PMS, which is 3.7 times higher than the bulk CN (BCN). Moreover, it also demonstrates good stability in a wide pH range (3-11) and good reusability in continuous runs. The superior performance of SCN was attributed to the photogenerated electron-mediated synergistic effect arising from its unique morphology and higher crystallinity. The superoxide radicals (& sdot;O2-) were revealed as the primary reactive oxygen radicals by electron spin resonance results and free radical quenching tests. Apart from that, singlet oxygen, hydroxyl radicals, sulfate radicals, and holes were also detected in the SCN/PMS/solar system, jointly contributing to the efficient degradation of BPA.