The degradation of tetrabromobisphenol A by metal-free graphene oxide in the dark

Abstract

Brominated flame retardants (BFRs) such as tetrabromobisphenol A (TBBPA) were widely detected in the environment. The ease of synthesis of graphene-based materials (GBMs) makes it an excellent metal-free carbon-based catalyst for the reductive debromination of TBBPA. Here we explore the complete debromination of TBBPA from the aqueous environment in the dark using metal-free graphene oxide (GO) and reduced GO (rGO). More importantly, radical scavenger experiments reveal the formation of superoxide radicals and singlet oxygen from the surface of GBMs leading to the debromination of TBBPA. GO shows an enhanced catalytic activity due to enriched O-functional groups on the surface than rGO, as observed by cyclic voltammetry and electrochemical impedance spectroscopy. In addition, the TBBPA degradation pathway was proposed with BPA as the end product and by-products were identified by mass spectroscopy. The complete TBBPA degradation was observed within 240 mins of reaction time (kobs = 8.6×10−3 min−1), which was significantly more efficient than the catalytic activity of other metal-based catalysts. Our study thus provides a new insight into the debromination mechanisms of TBBPA which would exhibit potential for future efficient catalyst development.