Weak-Bond-Based Photoreduction of Polybrominated Diphenyl Ethers on Graphene in Water

The photoreduction of polybrominated diphenyl ethers (PBDEs)-a kind of persistent organic pollutants with high hydrophobicity-was achieved on graphene in aqueous solution. We first observed that reduced graphene oxide (RGO) exhibited higher reaction rate than graphene oxide (GO). FT-IR and elementary analysis indicated that GO first was reduced to RGO at the beginning of the irradiation, and RGO is the real photoactive species. The theoretical calculations and adsorption experiments reveal a new photochemical debromination pathway based on the weak interaction, such as hydrophobic interaction, pi-pi interaction, and halogen-binding interaction between the PBDEs and RGO. These interactions enable the photoinduced electron transfer from the RGO to PBDEs and lead to the efficient reductive debromination of PBDEs. This study provides a green and low-cost method for removal of the high hydrophobicity halogen organic pollutants in water with environmentally benign carbon nanomaterials.