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Eva Fišerová - One of the best experts on this subject based on the ideXlab platform.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental science and pollution research international, 2003
    Co-Authors: Milan Bureš, Vladimír Pekárek, Jindřich Karban, Eva Fišerová
    Abstract:

    Background, Aims and Scope In the first part of this paper the main principles which control the Dehalogenation of polychlorinated aromatic compounds on municipal waste incineration fly ash (MWI-FA) have been discussed and the model fly ash of similar Dehalogenation activity has been proposed. Even if both systems show comparable Dehalogenation properties, the main question concerning the postulated identical reaction mechanism in both cases is left unanswered. The other very important point is to what extent is this dechlorination mechanism thermodynamically controlled. The same problem is often discussed in the literature also for the de novo synthetic reactions. From the data it is clear that metallic copper plays a decisive role in the mechanism of the Dehalogenation reaction. Although the results reported in the first part strongly support the idea that copper acts in this dechlorination as the reaction component, in contrast to its generally accepted catalytic behaviour, we believed that additional support for this conclusion can be obtained with the help of a thermodynamic interpretation of the mechanism of the reaction.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental Science and Pollution Research, 2003
    Co-Authors: Vladimír Pekárek, Jindřich Karban, Eva Fišerová, Michal Bureš, Věra Pacáková, Eva Večerniková
    Abstract:

    Background, Aims and Scope It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows Dehalogenation properties after heating it to 240-450°C. However, this property is not general, and fly ash samples do not possess Dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the Dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. Methods With the aim of accounting for the Dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in Dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350°C temperature range. Five different kinds of carbon were used, combined with conventional Cu° and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)_2, CuCl_2 and CuSO_4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. Conclusions The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu° to Cu+ or Cu^2+ is a prerequisite for the Dehalogenation to take place. Recommendation and Outlook Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.

Vladimír Pekárek - One of the best experts on this subject based on the ideXlab platform.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental science and pollution research international, 2003
    Co-Authors: Milan Bureš, Vladimír Pekárek, Jindřich Karban, Eva Fišerová
    Abstract:

    Background, Aims and Scope In the first part of this paper the main principles which control the Dehalogenation of polychlorinated aromatic compounds on municipal waste incineration fly ash (MWI-FA) have been discussed and the model fly ash of similar Dehalogenation activity has been proposed. Even if both systems show comparable Dehalogenation properties, the main question concerning the postulated identical reaction mechanism in both cases is left unanswered. The other very important point is to what extent is this dechlorination mechanism thermodynamically controlled. The same problem is often discussed in the literature also for the de novo synthetic reactions. From the data it is clear that metallic copper plays a decisive role in the mechanism of the Dehalogenation reaction. Although the results reported in the first part strongly support the idea that copper acts in this dechlorination as the reaction component, in contrast to its generally accepted catalytic behaviour, we believed that additional support for this conclusion can be obtained with the help of a thermodynamic interpretation of the mechanism of the reaction.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental Science and Pollution Research, 2003
    Co-Authors: Vladimír Pekárek, Jindřich Karban, Eva Fišerová, Michal Bureš, Věra Pacáková, Eva Večerniková
    Abstract:

    Background, Aims and Scope It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows Dehalogenation properties after heating it to 240-450°C. However, this property is not general, and fly ash samples do not possess Dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the Dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. Methods With the aim of accounting for the Dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in Dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350°C temperature range. Five different kinds of carbon were used, combined with conventional Cu° and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)_2, CuCl_2 and CuSO_4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. Conclusions The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu° to Cu+ or Cu^2+ is a prerequisite for the Dehalogenation to take place. Recommendation and Outlook Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.

Jindřich Karban - One of the best experts on this subject based on the ideXlab platform.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental science and pollution research international, 2003
    Co-Authors: Milan Bureš, Vladimír Pekárek, Jindřich Karban, Eva Fišerová
    Abstract:

    Background, Aims and Scope In the first part of this paper the main principles which control the Dehalogenation of polychlorinated aromatic compounds on municipal waste incineration fly ash (MWI-FA) have been discussed and the model fly ash of similar Dehalogenation activity has been proposed. Even if both systems show comparable Dehalogenation properties, the main question concerning the postulated identical reaction mechanism in both cases is left unanswered. The other very important point is to what extent is this dechlorination mechanism thermodynamically controlled. The same problem is often discussed in the literature also for the de novo synthetic reactions. From the data it is clear that metallic copper plays a decisive role in the mechanism of the Dehalogenation reaction. Although the results reported in the first part strongly support the idea that copper acts in this dechlorination as the reaction component, in contrast to its generally accepted catalytic behaviour, we believed that additional support for this conclusion can be obtained with the help of a thermodynamic interpretation of the mechanism of the reaction.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental Science and Pollution Research, 2003
    Co-Authors: Vladimír Pekárek, Jindřich Karban, Eva Fišerová, Michal Bureš, Věra Pacáková, Eva Večerniková
    Abstract:

    Background, Aims and Scope It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows Dehalogenation properties after heating it to 240-450°C. However, this property is not general, and fly ash samples do not possess Dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the Dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. Methods With the aim of accounting for the Dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in Dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350°C temperature range. Five different kinds of carbon were used, combined with conventional Cu° and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)_2, CuCl_2 and CuSO_4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. Conclusions The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu° to Cu+ or Cu^2+ is a prerequisite for the Dehalogenation to take place. Recommendation and Outlook Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.

Eva Večerniková - One of the best experts on this subject based on the ideXlab platform.

  • Dehalogenation potential of municipal waste incineration fly ash
    Environmental Science and Pollution Research, 2003
    Co-Authors: Vladimír Pekárek, Jindřich Karban, Eva Fišerová, Michal Bureš, Věra Pacáková, Eva Večerniková
    Abstract:

    Background, Aims and Scope It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows Dehalogenation properties after heating it to 240-450°C. However, this property is not general, and fly ash samples do not possess Dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the Dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. Methods With the aim of accounting for the Dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in Dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350°C temperature range. Five different kinds of carbon were used, combined with conventional Cu° and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)_2, CuCl_2 and CuSO_4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. Conclusions The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu° to Cu+ or Cu^2+ is a prerequisite for the Dehalogenation to take place. Recommendation and Outlook Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.

Jun Xiang - One of the best experts on this subject based on the ideXlab platform.

  • pyrolysis and Dehalogenation of plastics from waste electrical and electronic equipment weee a review
    Waste Management, 2013
    Co-Authors: Xiaoning Yang, Jun Xiang, Song Hu, Sheng Su
    Abstract:

    Abstract Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, Dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, Dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and Dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be ‘dehalogenating prior to pyrolysing plastics’, ‘performing Dehalogenation and pyrolysis at the same time’ or ‘pyrolysing plastics first then upgrading pyrolysis oils’. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and Dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process.

  • pyrolysis and Dehalogenation of plastics from waste electrical and electronic equipment weee a review
    Waste Management, 2013
    Co-Authors: Xiaoning Yang, Lushi Sun, Jun Xiang
    Abstract:

    Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, Dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, Dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and Dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be 'dehalogenating prior to pyrolysing plastics', 'performing Dehalogenation and pyrolysis at the same time' or 'pyrolysing plastics first then upgrading pyrolysis oils'. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and Dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process.