4,4′-Isopropylidenebis(2,6-dibromophenol) Photocatalytic Debromination on Nano- and Micro-Particles Fe3O4 Surface

Background: Tetrabromobisphenol A (4,4’-isopropylidenebis(2,6-dibromophenol), TBBPA) is one of the most widely used brominated flame retardants. Due to its widespread use, high lipophilicity, and persistence, it has been detected in various environmental samples. Therefore, it is of great significance to develop methods to efficiently remove TBBPA from the contaminated environment. Objective: The aim of our study was to examine photocatalytic dehalogenation of TBBPA on microand nano-sized Fe3O4 exposed to the visible light. The Fe3O4 catalyst was chosen due to its indisputable low impact on the environment. Methods: A solution of TBBPA (1.84 × 10-4 mol dm-3) with a pH = 8 with suspended catalyst was illuminated (light intensity about 1.1x1017 photons per second, spectrum range 200-600 nm) for 1 hour. Analysis of the reaction progress was carried out by HPLC measurements of TBBPA decay and potentiometric measurements of an increase in bromide concentration. Results: The degradation process seems to be the most effective for TBBPA in the reaction mixture containing the n-Fe3O4 (t0.5 ≈ 2 min). Slightly lower degradation efficacy is observed for TBBPA degradation in the presence of the μ-Fe3O4 (decay within the first 5 min). TBBPA decomposition of both n-Fe3O4 and μ-Fe3O4 is accompanied by different bromide concentrations time-profile. Conclusion: The photogenerated electron-induced degradation by dissociative-attachment to the aromatic ring was followed by bromine ion expulsion. The micro-magnetite showed a strong tendency for adsorption of bromide anions during the process, which could be adventurous for the overall waste-decontamination process.