TY - JOUR
T1 - Hybrid radical coupling during MnO2-mediated transformation of a mixture of organic UV filters
T2 - Chemistry and toxicity assessment
AU - Lam, Tsz Ki
AU - Law, Japhet Cheuk Fung
AU - Leung, Kelvin Sze Yin
N1 - Kelvin S.-Y. Leung thanks the Hong Kong Research Grants Council (HKBU 12302020) for their financial support. T.-K. Lam is supported by a postgraduate studentship offered by the University Grants Committee.
Publisher Copyright:
© 2024 Elsevier B.V.
PY - 2024/3/10
Y1 - 2024/3/10
N2 - Manganese oxide (MnO2) is one of the most abundant metal oxides, and it is renowned for its ability to degrade various phenolic micropollutants. However, under MnO2-mediated transformation, BP-3 transforms into 12 different radical-coupled transformation products (TPs) out of 15 identified TPs. These radical-coupled TPs are reported with adverse environmental impacts. This study explored the effects of MnO2 on organic UV filter mixtures and different water constituents (i.e., bicarbonate ion (HCO3−), humic acid (HA) and halide ions) in terms of degradation efficiency and transformation chemistry. When a mixture of benzophenone-3 (BP-3) and avobenzone (AVO) underwent transformation by MnO2, hybrid radical-coupled TPs derived from both organic UV filters were generated. These hybrid radical-coupled TPs were evaluated by an in silico prediction tool and Vibrio fischeri bioluminescence inhibition assay (VFBIA). Results showed that these TPs were potentially toxic to aquatic organisms, even more so than their parent compounds. The higher the concentration of HCO3−, HA, chloride ion (Cl−) and bromide ion (Br−), the greater the reduction in the efficiencies of degrading BP-3 and AVO. Contrastingly, in the presence of iodide ion (I−), degradation efficiencies of BP-3 and AVO were enhanced; however, iodinated TPs and iodinated radical-coupled TPs were formed, with questionable toxicity. This study has revealed the environmental risks of hybrid radical-coupled TPs, iodinated TPs and iodinated radical-coupled TPs when the organic UV filters BP-3 and AVO are transformed by MnO2.
AB - Manganese oxide (MnO2) is one of the most abundant metal oxides, and it is renowned for its ability to degrade various phenolic micropollutants. However, under MnO2-mediated transformation, BP-3 transforms into 12 different radical-coupled transformation products (TPs) out of 15 identified TPs. These radical-coupled TPs are reported with adverse environmental impacts. This study explored the effects of MnO2 on organic UV filter mixtures and different water constituents (i.e., bicarbonate ion (HCO3−), humic acid (HA) and halide ions) in terms of degradation efficiency and transformation chemistry. When a mixture of benzophenone-3 (BP-3) and avobenzone (AVO) underwent transformation by MnO2, hybrid radical-coupled TPs derived from both organic UV filters were generated. These hybrid radical-coupled TPs were evaluated by an in silico prediction tool and Vibrio fischeri bioluminescence inhibition assay (VFBIA). Results showed that these TPs were potentially toxic to aquatic organisms, even more so than their parent compounds. The higher the concentration of HCO3−, HA, chloride ion (Cl−) and bromide ion (Br−), the greater the reduction in the efficiencies of degrading BP-3 and AVO. Contrastingly, in the presence of iodide ion (I−), degradation efficiencies of BP-3 and AVO were enhanced; however, iodinated TPs and iodinated radical-coupled TPs were formed, with questionable toxicity. This study has revealed the environmental risks of hybrid radical-coupled TPs, iodinated TPs and iodinated radical-coupled TPs when the organic UV filters BP-3 and AVO are transformed by MnO2.
KW - Hybrid radical coupling
KW - MnO2-mediated transformation
KW - Organic UV filters
KW - Iodinated transformation products
KW - In vitro toxicity
UR - http://www.scopus.com/inward/record.url?scp=85182877316&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2024.170121
DO - 10.1016/j.scitotenv.2024.170121
M3 - Journal article
C2 - 38232841
AN - SCOPUS:85182877316
SN - 0048-9697
VL - 915
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 170121
ER -