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

Fenton reaction is most important in advanced oxidation processes, however, the sluggish kinetics of H2O2 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)/H2O2 system to produce hydroxyl radicals. Unlike the classical electron sacrifices, MG can enhance the Fe-O bond of FeOH2+ and Fe(III) oxidation potential, thus MG can further mediate and accelerate Fe(III) induced H2O2 oxidation to produce Fe(II) and initiate Fenton chain reactions. Kinetics model results reveal that the reaction rate constant between Fe(III) and H2O2 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.