Complexes of Fe(III)-organic pollutants that directly activate Fenton-like processes under visible light

Abstract

The major challenge of Fenton and Fenton-like technologies is promoting the effective transformation of Fe3+ to Fe2+. Photoinduced ligand-to-metal charge transfer (LMCT) enables charge to transfer effectively from the complex ligand to metal ions for the subsequent redox reactions. This study shows that photoactivated LMCTs relying on internal charge transfers occurred from the pollutant complex to the Fe3+ center and followed the in situ transformation of Fe3+ to Fe2+ without the addition of other ligands or agents. Using the antibiotic pollutant sulfamethoxazole (SMX), a direct Fe-SMX complex is formed and enables visible light to be used to activate peroxydisulfate (PDS) by Fe3+ for the rapid degradation of SMX at a rate 6.5-times higher than that observed by the conventional Fe2+/PDS system. This study outlines a new and cost-effective LMCT activation approach and broadens our knowledge of the ability of Fe3+ to be applied in Fenton-like reactions for environmental remediation.