The mechanism changes during bisphenol A degradation in three iron functionalized biochar/peroxymonosulfate systems: The crucial roles of iron contents and graphitized carbon layers

Three magnetic biochar nanocomposites named as C800-1, C800-2 and C800-3 with increased iron deposition amount, decreased graphitized degree and gradually destroyed graphitized carbon layers, respectively, were prepared using potassium ferrate as activator and corn straw as biomass. C800-1, C800-2 and C800-3 exhibited much different bisphenol A degradation effect in presence of peroxymonosulfate among which C800-3 owned the best catalytic performance. For the degradation mechanism, the dominant role of electron transfer pathway was gradually replaced by the SO4•– pathway with the increase of iron amount and the destruction of graphitized carbon layers. This work would provide a simple and feasible method, namely changing the ratio of potassium ferrate and biochar, to manipulate the radical and nonradical degradation pathway in PMS-based organic wastewater purification. [Display omitted] •Iron/biochar composites were used for PMS activation to degrade bisphenol A.•Electron transfer pathway was replaced by SO4•– pathway with increase of K2FeO4 dose.•The iron contents and graphitized carbon layers played crucial role on the SO4•– pathway.