Environmental photochemistry of PCDDs. 2. Quantum yields of the direct phototransformation of 1,2,3,7-tetra-, 1,3,6,8-tetra-, 1,2,3,4,6,7,8-hepta-, and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin in aqueous acetonitrile and their sunlight half-lives

Choudhry, Ghulam Ghaus; Webster, G. R. B.

doi:10.1021/jf00085a059

Cited by 29 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous investigations have shown that OCDF and OCDD are photodegradable (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In our experiments, a direct quantitative comparison between degradation rates of these compounds was performed.…”

Section: Introductionmentioning

confidence: 97%

A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD)

et al. 1995

View full text Add to dashboard Cite

A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD). Wagenaar, W.J.; Boelhouwers, E.J.; de Kok, H.A.M.; Groen, C.P.; van Houtenlaan, C.J.; Govers, H.A.J.; Olie, K.; de Gerlache, J.; de Rooij, C.G. Published in: Chemosphere DOI:10.1016/0045-6535(95)00158-5 Link to publication Citation for published version (APA):Wagenaar, W. J., Boelhouwers, E. J., de Kok, H. A. M., Groen, C. P., van Houtenlaan, C. J., Govers, H. A. J., ... de Rooij, C. G. (1995). A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD). Chemosphere, 31, 2983-2992. DOI: 10.1016/0045-6535(95)00158-5 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ABSTRACT Photolysis at 290 nm and higher wavelengths of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD) was studied in three organic solvents hexane, 1,4-dioxane and methanol. It appeared that the degradation kinetics strongly depended on the type of solvent. OCDD degraded fastest in hexane, whereas OCDF degraded fastest in methanol. Less than 5% of the total loss of OCDD degraded by reductive dechlorination, with preferential loss of chlorine atoms at the 1 or 9 positions. 35 to 50% of the total loss of OCDF degraded via reductive dechlorination, with preferential loss of lateral chlorine. OCDF degraded faster than OCDD in all studied solvents.Photolysis at 290 nm and higher wavelengths of OCDD and OCDF adsorbed onto alumina impregnated with copper (alumina/Cu) in the presence of natural and distilled water was also investigated. Under these more relevant environmental aquatic conditions, photolysis of OCDD and OCDF was much slower than photolysis in the studied organic solvents. Significant loss was only found for OCDF. A part of the loss of OCDF could be explained by reductive dechlorination; the results suggested that other mechanisms of degradation occurred in addition to reductive dechlorination.All photolysis experiments showed that OCDF was photochemically less stable than OCDD. INTRODUCTION.In general, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are

show abstract

Section: Introductionmentioning

confidence: 97%

A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD)

et al. 1995

View full text Add to dashboard Cite

show abstract

“…PCDDs can absorb near-UV light that is contained in sunlight and subsequently undergo a series of photochemical processes to induce their transformation or degradation. The photochemistry and photolytic properties of PCDDs have been studied in various media such as organic solvents ( 22 , 24 , 25 ), acetonitrile/water mixture ( − ), and on solid surfaces ( 25 , − . Most photoreactions of PCDDs were carried out in organic solvents because their water solubility is extremely low.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Specific Photolytic Behavior of Octachlorodibenzo-p-dioxin

Choi

Mhin

2004

Environ. Sci. Technol.

View full text Add to dashboard Cite

The photolysis of octachlorodibenzo-p-dioxin (OCDD) was investigated in various organic solvents under lambda > 300 nm irradiation. The rates of OCDD photolysis were highly solvent-specific. OCDD was photodegraded rapidly in toluene, n-hexane, CCl4, and 1-octanol, whereas it underwent negligible photodegradation in acetonitrile, acetone, and methanol. Both OCDD photolysis and fluorescence emission did not take place in very polar solvents because polar solvent molecules efficiently quenched the excited OCDD (OCDD*). The addition of acetonitrile to an OCDD solution in toluene rapidly quenched both the fluorescence emission and the photolysis rate, which can be described by Stern-Volmer analysis. The efficient photolysis in nonpolar (or less polar) solvents seems to be mediated through a charge-transfer path where the solvent and OCDD* act as an electron donor and acceptor, respectively. However, OCDD photolysis in CCl4 seems to represent the opposite case in which the solvent is an electron acceptor and OCDD* is an electron donor. Hammett sigma constants that approximately represent the electron-donating power in structurally related aromatic solvents show a good correlation with the photolysis rates. We propose that the solvent specificity in OCDD photolysis is mainly ascribed to the difference in the electron donating (or accepting) tendency among various solvents. When triethylamine that easily donates an electron to form a charge-transfer exciplex with OCDD* was added, a marked enhancement in the photolysis rate was observed.

show abstract

“…Overall, photochemical decomposition quantum yields for PCDDs decrease with increasing chlorination ( − ). PCDDs substituted at the 2,3,7,8 positions are more photochemically stable than non-2,3,7,8-substituted congeners ( − ).…”

Section: Introductionmentioning

confidence: 99%

Photochemical Mass Balance of 2,3,7,8-TeCDD in Aqueous Solution under UV Light Shows Formation of Chlorinated Dihydroxybiphenyls, Phenoxyphenols, and Dechlorination Products

Rayne

Wan

Ikonomou

et al. 2002

Environ. Sci. Technol.

View full text Add to dashboard Cite

Polychlorinated dibenzo-p-dioxins (PCDDs) are a class of halogenated diaryl compounds that are environmentally important because of their high toxicity and bioaccumulatory properties. There is an incomplete understanding of their photochemistry because the majority of photoproducts, as indicated by incomplete mass balances, have not been identified. We studied the photochemical transformation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TeCDD) in aqueous solution using 302 nm light. Our results allow for the first photochemical mass balance (92-99%) for this compound and confirm the operation of a novel photochemical pathway, which gives rise to 2,2'-dihydroxy-4,4',5,5'-tetrachlorobiphenyl (4,4',5,5'-TeCDHBP) at >50% conversion from the starting material. Rearrangement from 2,3,7,8-TeCDD to 4,4',5,5'-TeCDHBP takes place following preferential homolytic C-O bond cleavage via a proposed mechanism analogous to the parent dibenzo-p-dioxin system. Photochemical conversion from the starting material to dechlorinated PCDDs or chlorinated phenoxyphenols are minor pathways, although the exact contribution of the strictly dechlorination pathways remains uncertain because of the complexity of the system. The results suggest that the photochemical conversion of PCDDs to chlorinated dihydroxybiphenyls, which are also polychlorinated biphenyl (PCB) metabolites, may be an important part of their environmental fate.

show abstract

Environmental photochemistry of PCDDs. 2. Quantum yields of the direct phototransformation of 1,2,3,7-tetra-, 1,3,6,8-tetra-, 1,2,3,4,6,7,8-hepta-, and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin in aqueous acetonitrile and their sunlight half-lives

Cited by 29 publications

References 14 publications

A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD)

A comparative study of the photolytic degradation of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD)

Solvent-Specific Photolytic Behavior of Octachlorodibenzo-p-dioxin

Photochemical Mass Balance of 2,3,7,8-TeCDD in Aqueous Solution under UV Light Shows Formation of Chlorinated Dihydroxybiphenyls, Phenoxyphenols, and Dechlorination Products

Contact Info

Product

Resources

About