College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Environ Pollut. 2021 Feb 15;271:116406. doi: 10.1016/j.envpol.2020.116406. Epub 2020 Dec 30.
As an emerging brominated flame retardant (BFR), tetrabromobisphenol S (TBBPS) has been frequently detected in the environmental media and organisms. Knowledges on the transformation and fate of TBBPS in both environment and engineering systems are essential to its ecological risk assessment. Herein, we reported the photochemical decomposition of TBBPS in aqueous solution upon 254 nm ultraviolet irradiation (UV). Results show that TBBPS was highly photoreactive, most likely due to the presence of four ortho-bromine substituents. The molar absorption coefficient and quantum yield of TBBPS were found to be pH-dependent, with the monoanionic form being most photoreactive. A series of photoproducts were identified by solid phase extraction (SPE) combined with liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI(+)-MS/MS. The photolysis of TBBPS likely proceeded through photonucleophilic substitution, photoreductive debromination, and β-scission reactions. A ketocarbene, possibly derived from the lower lying excited triplet state, was proposed to be involved in the photolysis of TBBPS. Ion chromatography analysis revealed that debromination occurred quickly, and the yield of bromide (Br) approached 100% after 90 min irradiation. The presence of SRNOM and MRNOM inhibited the photodegradation rate of TBBPS, which is likely due to the light-screening and physical quenching effects of natural organic matter (NOM). Our results reveal that photolysis is an important process for the attenuation of TBBPS in aquatic system; however, naturally occurring species such as NOM can appreciably retard the decay of TBBPS.
作为一种新兴的溴系阻燃剂（BFR），四溴双酚 S（TBBPS）已在环境介质和生物体内频繁检出。了解 TBBPS 在环境和工程系统中的转化和归宿对于其生态风险评估至关重要。本文报道了 254nm 紫外光（UV）辐照下水溶液中 TBBPS 的光化学分解。结果表明，TBBPS 具有很高的光反应活性，这很可能归因于其四个邻位溴取代基的存在。TBBPS 的摩尔消光系数和量子产率被发现与 pH 值有关，其中单价阴离子形式的光反应活性最高。通过固相萃取（SPE）与液相色谱-电喷雾电离-三重四极杆质谱联用（LC-ESI(+)-MS/MS 鉴定了一系列光产物。TBBPS 的光解可能通过光亲核取代、光还原脱溴和β断裂反应进行。提出了一种酮卡宾，可能来自较低的激发三重态，参与 TBBPS 的光解。离子色谱分析表明，脱溴反应迅速，90min 辐照后溴化物（Br）的产率接近 100%。SRNOM 和 MRNOM 的存在抑制了 TBBPS 的光降解速率，这可能是由于天然有机物（NOM）的光屏蔽和物理猝灭效应。我们的结果表明，光解是水体中 TBBPS 衰减的重要过程；然而，天然存在的物质，如 NOM，可以显著减缓 TBBPS 的衰减。
