Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A: Kinetics, reaction pathways, and formation of brominated by-products.
Degradation of tetrabromobisphenol A (TBBPA), a flame retardant widely spread in the environment, in Co(II) catalyzed peroxymonosulfate (PMS) oxidation process was systematically explored. The second-order-rate constant for reaction of sulfate radical (SO4(-)) with TBBPA was determined to be 5.27×10(10)M(-1)s(-1). Apparently, degradation of TBBPA showed first-order kinetics to the concentrations of both Co(II) and PMS. The presence of humic acid (HA) and bicarbonate inhibited TBBPA degradation, most likely due to their competition for SO4(-). Degradation of TBBPA was initiated by an electron abstraction from one of the phenolic rings. Detailed transformation pathways were proposed, including β-scission of isopropyl bridge, phenolic ring oxidation, debromination and coupling reactions. Further oxidative degradation of intermediates in Co(II)/PMS process yielded brominated disinfection by-products (Br-DBPs) such as bromoform and brominated acetic acids. Evolution profile of Br-DBPs showed an initially increasing and then decreasing pattern with maximum concentrations occurring around 6-10h. The presence of HA enhanced the formation of Br-DBPs significantly. These findings reveal potentially important, but previously unrecognized, formation of Br-DBPs during sulfate radical-based oxidation of bromide-containing organic compounds that may pose toxicological risks to human health.
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
Yuefei
Y
Ji
Nanjing Institute of Environmental Science, Ministry of Environmental Protection of PRC, Nanjing 210042, China.
Deyang
D
Kong
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: jhlu@njau.edu.cn.
Junhe
J
Lu
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
Hao
H
Jin
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
Fuxing
F
Kang
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
Xiaoming
X
Yin
Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
Quansuo
Q
Zhou
Brominated disinfection by-products; Cobalt catalyzed peroxymonosulfate oxidation; Sulfate radical; Tetrabromobisphenol A