Mechanisms of Formation and Destruction of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Heterogeneous Systems

Addink, Ruud; Olie, K.

doi:10.1021/es00006a002

Cited by 328 publications

(196 citation statements)

References 78 publications

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“…The mechanisms of PCDD/Fs formation in MSWI have been elucidated as the following three paths: (i) high-temperature pyrosynthesis, (ii) low-temperature de novo synthesis, (iii) formation from different organic precursors such as chlorophenols, chlorobenzenes, etc., and PCDD/Fs formation from (iii) is 10 2 -10 5 times faster than from (ii) (Addink and Olie, 1995;Tuppurainen et al, 1998;McKay, 2002;Stanmore, 2004). Model studies also showed that PCDD/ Fs formation from precursors is likely the predominance of the two proposed pathways (ii) and (iii) (Dickson et al, 1992).…”

Section: Introductionmentioning

confidence: 89%

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

et al. 2005

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The total suppressing efficiencies of several metal oxides including CaO, BaO, PbO, Ag 2 O, HgO and SnO which have lower Z/r (charge to radius ratio) <2 are all over 90%. The theories of generalized acid-base and atomic parameter (Z/r) were used to speculate the effecting mechanisms. The factors including time and temperature on suppressing efficiencies of CaO, BaO and PbO have also been studied in the present paper. The results showed that the total suppressing efficiencies of CaO, BaO and PbO increase with the increase of heated time and temperature.

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Section: Introductionmentioning

confidence: 89%

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

et al. 2005

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“…It is widely recognized that fly ash is a matrix on which heterogeneous catalyzed reactions occur, so it was used as the matrix for the thermal experiments described here, offering the advantage that as close as possible to a ''real'' active surface (Milligan and Altwicker, 1993;Addink and Olie, 1995;Pekárek et al, 2007). Fly ash was collected from a reverberatory furnace of a secondary copper smelter in eastern China.…”

Section: Experimental Designmentioning

confidence: 99%

“…The SeCu fly ash was compared with fly ash from other thermal-related processes, and it was found that the Cu concentration was much higher in the SeCu fly ash than in fly ash from a MSWI plant (0.47-0.33 mg g À1 ) (Cobo et al, 2009) and fly ash from an integrated iron and steel facility (0.12-7.95 mg g À1 ) (Tsai et al, 2007). PCNs are usually formed along with PCDDs and PCDFs, and the formation of all of these chemicals is probably favored by the presence of carbon, chlorine, and transition metals, such as Cu, on the surfaces of fly ash particles (Addink and Olie, 1995;Hatanaka et al, 2004;Stanmore, 2004;Chin et al, 2011). Therefore, we speculated that the fly ash we had prepared could lead to the formation of PCNs under favorable conditions.…”

Section: Experimental Designmentioning

confidence: 99%

Fly ash-mediated formation of polychlorinated naphthalenes during secondary copper smelting and mechanistic aspects

2015

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“…Hightemperature incineration is currently the principal method of PCBs destruction (Lee and Huffman, 1989). However, there are considerable problems, including the high cost and the possible generation of more toxic polychlorinated dibenzodioxins/polychlorinated dibenzofurans during incineration (Addink and Olie, 1995). Catalytic degradation at lower temperature involving metal oxides as a safe alternative technology is thought as the most promising method, due to its relatively low costs, high levels of activity (Subbanna et al, 1988;Tanaka et al, 2005;Huang et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Huang

Shi

et al. 2016

Chemosphere

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h i g h l i g h t s• 1% mol Ca species enhanced the activity of Fe 2 O 3 in the degradation of DecaCB.• Dominant Nona-MonoCB isomers were determined during hydrodechlorination reaction.• Thermodynamic and/or steric effects drive conversion.• Steric effect prevented the hydrodechlorination at ortho-positions. a r t i c l e i n f o b s t r a c tDegradation reaction of decachlorobiphenyl (PCB-209) was investigated over the synthesized Ca speciesdoped Fe 2 O 3 at 300°C. The 1%Ca-Fe 2 O 3 exhibited the highest activity among the four catalysts prepared with the pseudo-first order reaction at k obs = 0.103 min −1 . PCB-207, PCB-197, PCB-176, PCB-184, PCB-150, PCB-136, PCB-148, PCB-104, PCB-96, PCB-54, PCB-19, PCB-4 and PCB-1 were identified as the dominant isomers in their respective nonachlorobiphenyl (NonaCB) to monochlorobiphenyl (MonoCB) homologue groups. Analysis of the hydrodechlorination products indicated that dechlorination was much more favored on meta-and para-than on ortho-positions. The formation of significantly predominant NonaCB and octachlorobiphenyl (OctaCB) isomers was attributed to lower energy principles and to the 90°dihe-dral angles of two aromatic rings which prevented the hydrodechlorination at ortho-positions. When the number of chlorine atoms is not more than 7, the steric effect supports the formation of predominant PCB isomers having chlorines at four ortho-positions. During the dechlorination of tetrachlorobiphenyl (TetraCB) formed to generate monochlorobiphenyl (MonoCB) isomers, the chlorine atoms fully substituted at the ortho-positions have to be successively removed, with the first two dechlorinations preferentially occurring at the two different benzene rings. This is dissimilar to that of octachloronaphthalene in which the hydrodechlorination reaction happened preferentially at ortho-position due to the existence of steric effects. The opposite roles of the steric effect in ortho-position between PCB-209 and PCN-75 might be due to the difference of the π -conjugated plane caused by the dihedral angle of 90°and 0°of the two aromatic rings.

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Mechanisms of Formation and Destruction of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Heterogeneous Systems

Cited by 328 publications

References 78 publications

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

Fly ash-mediated formation of polychlorinated naphthalenes during secondary copper smelting and mechanistic aspects

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

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