Ligand-Assisted Sequential Redox Degradation of Tetrabromobisphenol A Using Bimetallic Zero-Valent Iron Nanoparticles

Abstract

This study presents a sequential reduction-oxidation (redox) process composed of a reduction process using bismuth-modified zerovalent iron nanoparticles (Bi/Fe-0 NPs) and a ligand-enhanced oxidation process for the complete removal of tetrabromobisphenol A (TBBPA). In the first reduction process, TBBPA was reductively degraded to bisphenol A (BPA) by Bi/Fe-0 NPs. In the subsequent oxidation process, citric acid (CA) was used to enhance the oxidation capability for degradation of BPA over Bi/Fe-0 NPs in the presence of oxygen, thereby completely degrading TBBPA. The addition of CA to oxygen-containing solution of Bi/Fe-0 NPs significantly promoted the production of reactive oxygen species (ROS) by accelerating the rate of key reactions through its ligand function, which could form an Fe(III)-citrate complex. The intermediates formed during the sequential redox treatment were identified, and the plausible degradation pathway of TBBPA was proposed. These results provide a new strategy for degradation of various recalcitrant pollutants.