Efficient Oxidative Debromination of Decabromodiphenyl Ether by TiO2‑Mediated Photocatalysis in Aqueous Environment

• Published in: Environmental science & technology Vol. 47; no. 1; pp. 518 - 525
• Main Authors: Huang, Aizhen, Wang, Nan, Lei, Ming, Zhu, Lihua, Zhang, Yingying, Lin, Zhifen, Yin, Daqiang, Tang, Heqing
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 02.01.2013
• Subjects: Applied sciences; Bromine - chemistry; Catalysis; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Flame Retardants - radiation effects; Global environmental pollution; Halogenated Diphenyl Ethers - chemistry; Halogenated Diphenyl Ethers - radiation effects; Oxidation-Reduction; Photochemistry; Pollution; Pollution, environment geology; Titanium - chemistry; Titanium - radiation effects; Ultraviolet Rays; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - radiation effects; Water Purification - methods; Debromination; Dehalogenation; Ether; Photocatalysis; Flame retardant; Organic bromine compounds; Low volatile compound; Persistent organic pollutant; Pollution; Ultraviolet radiation; Polybrominated diphenyl ethers; Decontamination; Aqueous medium; Reaction mechanism; Environment; Oxidation; Titanium oxide; Photooxidation; Organic compounds; Photochemical degradation
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es302935e

Direct evidence was first demonstrated for the oxidative degradation of decabromodiphenyl ether (BDE209) in aqueous TiO2 dispersions under UV irradiation (λ > 340 nm). BDE209 was hardly debrominated over TiO2 in UV-irradiated acetonitrile dispersions, but the addition of water into the dispersions greatly enhanced its photocatalytic oxidative debromination. The debromination efficiency of BDE209 as high as 95.6% was achieved in aqueous TiO2 dispersions after 12 h of UV irradiation. The photocatalytic oxidation of BDE209 resulted in generation of aromatic ring-opening intermediates such as brominated dienoic acids, which were further degraded by prolonging UV irradiation time. The photocatalytic oxidative debromination of BDE209 was further confirmed by the observation that the BDE209 degradation in water–acetonitrile mixtures with different water contents was positively correlated with the formation of •OH radicals, but not photogenerated electrons. The use of water not only avoided the scavenging of reactive radicals by organic solvent but also enhanced the adsorption of BDE209 on the surface of TiO2, both of which favor the contact of BDE209 with photogenerated holes and •OH species. The confirmation of efficient oxidative degradation and debromination of BDE209 is very important for finding new ways to remove polybrominated diphenyl ethers from the environment.