Photolysis of Low-Brominated Diphenyl Ethers and Their Reactive Oxygen Species-Related Reaction Mechanisms in an Aqueous System

To date, no report was concerned with participation of reactive oxygen species in waters during photolysis of low-brominated diphenyl ethers (LBDEs). Herein, we found that electron spin resonance (ESR) signals rapidly increased with increasing irradiation time in the solution of LBDEs and 4-oxo-TMP solutions. But this phenomenon did not occur in the presence of NaN(3) ((1)O(2) quencher) demonstrating generation of (1)O(2) in process of LBDEs photolysis. The indirect photolytic contribution rate for BDE-47 and BDE-28 was 18.8% and 17.3% via (1)O(2), and 4.9% and 6.6% via ·OH, respectively. Both D(2)O and NaN(3) experiments proved that the indirect photolysis of LBDEs was primarily attributable to (1)O(2). The bimolecular reaction rate constants of (1)O(2) with BDE-47 and BDE-28 were 3.12 and 3.64 × 10(6) M(-1) s(-1), respectively. The rate constants for BDE-47 and BDE-28 (9.01 and 17.52 × 10(−3) min(-1)), added to isopropyl alcohol, were very close to those (9.65 and 18.42 × 10(−3) min(-1)) in water, proving the less indirect photolytic contribution of ·OH in water. This is the first comprehensive investigation examining the indirect photolysis of LBDEs in aqueous solution.