Various MnO2 structures have been extensively applied in catalysis. In this study,γ-MnO2,α-MnO2, and δ-MnO2 with corresponding rod, tube, and hierarchical architecture morphologies were prepared and applied for the...Various MnO2 structures have been extensively applied in catalysis. In this study,γ-MnO2,α-MnO2, and δ-MnO2 with corresponding rod, tube, and hierarchical architecture morphologies were prepared and applied for the catalytic oxidation of chlorobenzene (CB). The redox ability, H2O activation behavior, and acidity of MnO2 were analyzed using a range of techniques, including TPR, H2O-TPD, XPS, and pyridine-IR. The catalytic activities in CB oxidation were assessed;this revealed that γ-MnO2 exhibited the highest activity and best stability, owing to its enriched surface oxygen vacancies that functioned to activate O2 and H2O, and capture labile chlorine, which reacted with dissociated H2O to form HCl. All the MnO2 phases generated toxic polychlorinated by-products, including CHCl3, CCl4, C2HCl3, and C2Cl4, indicating the occurrence of electrophilic chlorination during CB oxidation. In particular, the dichlorobenzene detected in the effluents of α-MnO2 might generate unintended dioxins via a nucleophilic substitution reaction.展开更多
Polychlorinated naphthalene （PCNs） have similar structure and toxicity with dioxin class （PCDD/Fs）, it can be detected in the global environmental and biological samples. This paper introduces the main sources of ...Polychlorinated naphthalene （PCNs） have similar structure and toxicity with dioxin class （PCDD/Fs）, it can be detected in the global environmental and biological samples. This paper introduces the main sources of PCNs in the environment and environmental fate, introduced emphasis with the emission characteristics of PCNs in burning and metal smelting process, this article summarized the current PCNs city environmental and biotic pollution level and distribution characteristics, summarized and discussed related research of PCNs pollution level and distribution characteristics near the various environmental media and organisms in the city. Finally, the paper put forward the research progress of PCNs in related research areas and challenges.展开更多
Concentrations of PCDD/Fs, dioxin-like PCBs as well as six indicator PCBs were determined in animal origin foods collected from Hong Kong retail market during 2008-2010. The dietary intake of an average Hong Kong adul...Concentrations of PCDD/Fs, dioxin-like PCBs as well as six indicator PCBs were determined in animal origin foods collected from Hong Kong retail market during 2008-2010. The dietary intake of an average Hong Kong adult resident was estimated to be 0.806-0.833 pg WHO-TEQ kg^-1 b.w. d^-1 of dioxin-like compounds, lower than the tolerable daily intake introduced by WHO. The 95th percentile consumer were exposed by dietary at the level of 2.72 to 2.81 pg WHO-TEQ kg^-1 b.w. d^-1 or 81.6-84.3 pg WHO-TEQ kg^-1 b.w. month^-1 , higher than 70 pg WHO-TEQ kg t b.w. month^-1. DL-PCBs contributed 49.2% of total TEQ intake. The daily intake of indicator PCB was 2.83 ng kg^-1 b.w. d^-1. Approximately 2/3 of dietary intake of dioxin-like compounds came from sea food products. Ten brands of infant formula products were tested and the potential dietary intake of formula-fed infants of Hong Kong was estimated to be 1.46-1.58 pg WHO-TEQ kg^-1 b.w. d^-1 during 1st month and decreases afterwards.展开更多
基金supported by the Outstanding Youth Project of Zhejiang Natural Science Foundation(LR19E080004)the National Natural Science Foundation of China(51478418)~~
文摘Various MnO2 structures have been extensively applied in catalysis. In this study,γ-MnO2,α-MnO2, and δ-MnO2 with corresponding rod, tube, and hierarchical architecture morphologies were prepared and applied for the catalytic oxidation of chlorobenzene (CB). The redox ability, H2O activation behavior, and acidity of MnO2 were analyzed using a range of techniques, including TPR, H2O-TPD, XPS, and pyridine-IR. The catalytic activities in CB oxidation were assessed;this revealed that γ-MnO2 exhibited the highest activity and best stability, owing to its enriched surface oxygen vacancies that functioned to activate O2 and H2O, and capture labile chlorine, which reacted with dissociated H2O to form HCl. All the MnO2 phases generated toxic polychlorinated by-products, including CHCl3, CCl4, C2HCl3, and C2Cl4, indicating the occurrence of electrophilic chlorination during CB oxidation. In particular, the dichlorobenzene detected in the effluents of α-MnO2 might generate unintended dioxins via a nucleophilic substitution reaction.
文摘Polychlorinated naphthalene （PCNs） have similar structure and toxicity with dioxin class （PCDD/Fs）, it can be detected in the global environmental and biological samples. This paper introduces the main sources of PCNs in the environment and environmental fate, introduced emphasis with the emission characteristics of PCNs in burning and metal smelting process, this article summarized the current PCNs city environmental and biotic pollution level and distribution characteristics, summarized and discussed related research of PCNs pollution level and distribution characteristics near the various environmental media and organisms in the city. Finally, the paper put forward the research progress of PCNs in related research areas and challenges.
基金supported by the National Natural Science Foundation of China(21175025)
文摘Concentrations of PCDD/Fs, dioxin-like PCBs as well as six indicator PCBs were determined in animal origin foods collected from Hong Kong retail market during 2008-2010. The dietary intake of an average Hong Kong adult resident was estimated to be 0.806-0.833 pg WHO-TEQ kg^-1 b.w. d^-1 of dioxin-like compounds, lower than the tolerable daily intake introduced by WHO. The 95th percentile consumer were exposed by dietary at the level of 2.72 to 2.81 pg WHO-TEQ kg^-1 b.w. d^-1 or 81.6-84.3 pg WHO-TEQ kg^-1 b.w. month^-1 , higher than 70 pg WHO-TEQ kg t b.w. month^-1. DL-PCBs contributed 49.2% of total TEQ intake. The daily intake of indicator PCB was 2.83 ng kg^-1 b.w. d^-1. Approximately 2/3 of dietary intake of dioxin-like compounds came from sea food products. Ten brands of infant formula products were tested and the potential dietary intake of formula-fed infants of Hong Kong was estimated to be 1.46-1.58 pg WHO-TEQ kg^-1 b.w. d^-1 during 1st month and decreases afterwards.
