New insight into carbon materials enhanced Fenton oxidation: A strategy for green iron(III)/iron(II) cycles

• It is an universal property of carbon materials for enhancing Fenton oxidation. • Carbon materials can boost the oxidation potential of Fe(III) species. • A new insight into carbon materials mediated green Fe(III)/Fe(II) cycles. • The kinetic model was set up to analyze MG mediated Fenton chain reactions. Fenton reaction is most important in advanced oxidation processes, however, the sluggish kinetics of H 2 O 2 induced Fe(II) regeneration relatively limits the hydroxyl radicals generation. This study finds that carbon catalysis is a green and sustainable strategy to boost the Fenton chemistry and provides a new insight to carbon mediated Fe(III)/Fe(II) cycles. Multilayer graphene (MG), as a typical carbon material, can significantly enhance the Fe(III)/H 2 O 2 system to produce hydroxyl radicals. Unlike the classical electron sacrifices, MG can enhance the Fe-O bond of FeOH 2+ and Fe(III) oxidation potential, thus MG can further mediate and accelerate Fe(III) induced H 2 O 2 oxidation to produce Fe(II) and initiate Fenton chain reactions. Kinetics model results reveal that the reaction rate constant between Fe(III) and H 2 O 2 on MG surface is at least 100 times higher than that in aqueous solution. Therefore, carbon catalysis can overcome the speed-limiting process of Fenton system by elevating Fe(III) reactivity at acidic conditions.