Degradation of octane using an efficient and stable core-shell Fe3O4@C during Fenton processes: Enhanced mass transfer, adsorption and catalysis

•Core-shell Fe3O4@C acts as multifunctional microreactor for refractory VOC removal.•High octane removal efficiency and low-level toxic byproduct generation are achieved.•DFT calculation reveals the key role of FeOC bond during regeneration of Fe(II).•The adsorption process is enhanced by the carbonyl sites.•The advanced oxidation mechanism and the octane degradation pathway are proposed.