C60 Fullerol promoted Fe(III)/H2O2 Fenton oxidation: Role of photosensitive Fe(III)-Fullerol complex

Abstract

Hydroxylated C60 Fullerene (Fullerol) induced photochemical production of reactive oxygen species (ROS, e.g. singlet oxygen (1O2) and hydroxyl radical (OH)) is a slow process, and the role of its surface groups other than high water-solubility is still lack of investigation. In this study, we demonstrate Fullerol can promote Fe(III)/Fe(II) cycles to degrade dimethyl phthalate (DMP) in Fe(III)/H2O2 Fenton system as both an electron donor and an electron-transfer mediator. At acidic condition, the formation of carbonyl and carboxyl via pinacol rearrangement and subsequent keto-enol isomerization can produce cage-opened structure of Fullerol, resulting in the pH-dependent formation of Fe(III)-Fullerol complex. Two pathways of Fe(II) recovery via intramolecular electron transfer of Fe(III)-Fullerol complex to enhance Fe(III)/H2O2 Fenton oxidation were proposed: 1) Fullerol direct reduces Fe(III) into Fe(II) as an electron donor in dark, and it was strongly enhanced under visible light irradiation; 2) Fullerol mediates electron transfer from electron donor (e.g. hydrogen peroxide and organics) to Fe(III) in visible light condition. Furthermore, DMP degradation pathway was proposed based on variation of main intermediates.