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.