Nitrogen-doped carbon enhances Fe0 activation for efficient tetrabromobisphenol a decontamination and its removal mechanism

Abstract

Biomass derived N-doped carbon-encapsulated nano zero-valent iron (NC@Fe0) was successfully used to activate hydrogen peroxide (H2O2) for efficient oxidation of tetrabromobisphenol A (TBBPA). The as-prepared NC@Fe0 exhibited high H2O2 activation performance, with a TBBPA removal efficiency of 95.9 % and an oxidation rate constant of 0.031 min−1. The quenching experiments and electrochemical tests showed that the overall contributions of nonradical pathways were over 83.0 %, via synergistic production of singlet oxygen (1O2) and an electron transfer process (ETP). Specifically, the N group on NC@Fe0 greatly enhanced 1O2 production, while formation of surface complexes (OVs-H2O2) was responsible for the ETP mechanism. High Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometer (HPLC-Q-TOF MS/MS) and Toxicity Estimation Software Tool (T.E.S.T) clearly demonstrated that products were mainly generated via debromination and β-scission, where the products were less toxic than the parent. During practical wastewater, in both lake water and domestic wastewaters, NC@Fe0/H2O2 removed over 91.0 % of TBBPA. This study highlighted the considerable contribution of nonradicals in contaminant removal and enriched our understandings of a green activator for future environmental remediations.