Peroxymonosulfate activation through magnetic Fe3C/Fe doped biochar from natural loofah sponges for carbamazepine degradation

•3D magnetic Fe3C/Fe doped biochar from loofah sponges was successfully prepared.•Radical and non-radical reactive species contribute to CBZ degradation.•The plausible activation mechanism of 0.5Fe@LSBC800 activated PMS was revealed.•The CBZ degradation pathways in the 0.5Fe@LSBC800 system were determined. Taking advantage of the unique properties of the channel structure of loofah, a series of three-dimensional (3D) magnetic Fe3C/Fe-doped biochar was prepared by simple and feasible pyrolysis of the mixture of raw loofah sponges and FeCl3·6H2O, and used as the functional activator of peroxymonosulfate (PMS) for carbamazepine (CBZ) removal. The optimized 0.5Fe@LSBC800 showed the optimum catalytic activity and almost complete CBZ was removed in the 0.5Fe@LSBC800/PMS system within 30 min, which was significantly higher than that of Fe0/PMS (44 %), Fe3O4/PMS (17 %), and Fe3C/PMS (45 %) systems due to the synergistic effect between the doped Fe species and 3D biochar with abundant nucleophilic groups (OH) and electrophilic groups (CO). Furthermore, the possible catalytic mechanism of PMS activation by 0.5Fe@LSBC800 was proposed based on the comprehensive characterization analysis, chemical probe experiments, and electron paramagnetic resonance test. The CBZ degradation pathways in the 0.5Fe@LSBC800/PMS system were proposed according to the detected degradation intermediates, and the ecotoxicity of CBZ and its by-products was evaluated. At last, the practical application potential of the 0.5Fe@LSBC800/PMS system was evaluated.