Photodecomposition of tetrabromobisphenol A in aqueous humic acid suspension by irradiation with light of various wavelengths

Abstract

The reactive species generated in aqueous 3,3',5,5'-tetrabromobisphenol A (TBBPA)/humic acid (HA) suspensions above the TBBPA pKa (∼7.4), under various light-irradiation conditions, namely ambient and ultraviolet light, were investigated using electron paramagnetic resonance (EPR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS). We confirmed that singlet oxygen and OH radicals are the key reactive oxygen species generated at wavelengths greater than 400 and 300 nm, respectively. The amount of 2,6-dibromo-p-benzosemiquinone anion radicals (2,6-DBSQ(•-)) formed under irradiation at 400 nm increased linearly with respect to irradiation time; the initial reaction rate was 7.03 × 10(-9) mol g(-1) HA s(-1). The rate increased with increasing pH and light intensity. LC-MS and EPR spectroscopy showed that tribromohydroxybisphenol A was formed under irradiation at 300 nm via reaction of OH radicals with TBBPA. This study, for the first time, shows that the main byproducts formed during irradiation at wavelengths above 300 nm are 2,6-DBSQ(•-) and tribromohydroxybisphenol A, generated from singlet oxygen ((1)O2) and OH radicals, respectively. Photodecomposition of TBBPA in the environment may occur by formation of (1)O2 and OH radicals.

Photodegradation of brominated flame retardants in polystyrene: Quantum yields, products and influencing factors

“…Some of the commonly used NBFRs include decabromodiphenyl ethane or 1,2bis(pentabromodiphenyl)ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB or EHTBB), bis(2ethylhexyl)-3,4,5,6-tetrabromo-phthalate (TBPH or BEHTBP), tetrabromobisphenol Abis(2,3-dibromopropylether) (TBBPA-DBPE) and tetrabromobisphenol A bis (allyl) ether (TBBPA-BAE). At present, the most widely used BFR is TBBPA (50% of BFRs currently used) with an estimated annual production volume of 130.000 tons (Han et al, 2016). TBBPA-containing materials are used in the manufacturing of office and home electronic equipment, such as computer printed circuit boards, mobile phones, televisions, washing machines, etc.…”

“…Moreover, it has been found in exposed humans and animals and was reported to be neurotoxic and endocrine disruptor (Jakobsson et al, 2002;Cariou et al, 2008;Van der Ven et al, 2008;Geens et al, 2009;Dourson, 2015;Liu et al, 2016;Gong et al, 2017;Inthavong et al, 2017). Various studies have investigated the transformation pathways of TBBPA in the environment, in particularly photodegradation in surface water (Eriksson et al, 2004b;Wang et al, 2015b;Han et al, 2016). Direct photolysis of TBBPA under solar irradiation was found to occur in aqueous solution and via photosensitized reactions with OH radicals and singlet oxygen generated by irradiation of humic substances (Eriksson et al, 2004b;Han et al, 2009;Wang et al, 2015b;Han et al, 2016).…”

“…Various studies have investigated the transformation pathways of TBBPA in the environment, in particularly photodegradation in surface water (Eriksson et al, 2004b;Wang et al, 2015b;Han et al, 2016). Direct photolysis of TBBPA under solar irradiation was found to occur in aqueous solution and via photosensitized reactions with OH radicals and singlet oxygen generated by irradiation of humic substances (Eriksson et al, 2004b;Han et al, 2009;Wang et al, 2015b;Han et al, 2016). The major phototransformation pathways included debromination and oxidation (Eriksson et al, 2004b;Wang et al, 2015b;Han et al, 2016).…”

“…Direct photolysis of TBBPA under solar irradiation was found to occur in aqueous solution and via photosensitized reactions with OH radicals and singlet oxygen generated by irradiation of humic substances (Eriksson et al, 2004b;Han et al, 2009;Wang et al, 2015b;Han et al, 2016). The major phototransformation pathways included debromination and oxidation (Eriksson et al, 2004b;Wang et al, 2015b;Han et al, 2016). While these studies shed light on the photoreactivity of TBBPA in water, no data is available to date on the kinetics and photoproducts of TBBPA in solid polymer matrices as well as on the photodegradation of some of its NBFR derivatives (TBBPA-DBPE and TBBPA-BAE).…”

A DFT/TDDFT study on the mechanisms of direct and indirect photodegradation of tetrabromobisphenol A in water

“…A small number of studies have focused on the photodegradation of TBBPA via $OH and 1 O 2 (Eriksson et al, 2004;Bao and Niu, 2015;Wang et al, 2015b;Han et al, 2016). Wang et al (2015b) reported that the photolysis of TBBPA could occur with 1 O 2 in an aqueous solution under simulated-solar-light irradiation.…”