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| 2. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Chimney emissions from small-scale burning of pellets and fuelwood - examples referring to different combustion appliances
- 2004
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In: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 27:6, s. 557-561
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Journal article (peer-reviewed)abstract
- Most wood boilers used for residential heating today are old-fashioned and emit large quantities of organic compounds. The installation of a pellet burner and a change to wood pellets as fuel normally decreases the emissions remarkably. In this study, the emissions from different equipment for burning of wood and pellets are compared. The organic fraction of smoke from traditional wood burning is to a great extent composed of methoxyphenols, with antioxidant effects. Methoxyphenols were also identified in smoke from pellet stoves. A fuelwood boiler or a furnace with an inserted pellet burner is heated to a higher combustion temperature, decreasing the total amount of organic compounds in the smoke. Above 800 °C, methoxyphenols are thermally decomposed and carcinogenic polycyclic aromatic compounds (PACs) are formed. The combustion-formed aromatic hydrocarbon benzene is present in smoke from all kinds of burning, but the proportion relative to primary organic compounds increases with increasing combustion temperature. In smoke from an environmentally labelled wood boiler and from some pellet burning devices, the levels of PAC and benzene were found to be low. Evidently, the combustion was nearly complete. Although the change from wood to pellets significantly decreases the emissions, considerable differences exist between various combinations of pellet burners and boiler furnaces.
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| 3. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Coniferyl alcohol from newsprint burning
- 2000
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In: Nordic pulp and paper journal. ; 15, s. 98-100
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Journal article (peer-reviewed)abstract
- Coniferyl alcohol constitutes almost half of the amount of methoxyphenols in smoke from choked burning of newsprint produced from thermomechanical pulp. The results indicate that coniferyl alcohol is a key component not only in biosynthesis but also in thermal decomposition of lignin. The trans isomer was formed in 5-10 times larger amounts than the cis isomer. Coniferyl alcohol and the oxidised analogue coniferaldehyde were also shown to be the most prominent methoxyphenols in chimney smoke from stove burning of newsprint.
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| 4. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Gas chromatographic and mass spectrometric analyses of 36 lignin-related methoxyphenols from uncontrolled combustion of wood
- 1998
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In: Journal of Chromatography A. ; 824, s. 205-210
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Journal article (peer-reviewed)abstract
- Eighteen 4-hydroxy-3-methoxyphenyl (guaiacyl) compounds in wood smoke from spruce, and 18 4-hydroxy-3,5-dimethoxyphenyl (syringyl) analogues in birchwood smoke were analysed. Smoke samples were taken by a gas syringe from wood burning under varying but more or less choked conditions in laboratory pot experiments. Retention index data for a methylsilicone column and basic mass spectral data are given for all compounds. Retention index in combination with molecular mass and structure-specific fragment ions greatly facilitates qualitative analysis. The syringyl and guaiacyl analogues differ by 240 units in retention index and the matching structure-specific ions in their mass spectra by 30 mass units. The identified methoxyphenols differ in the structure of the sidechain, which may be lacking, an alkyl group, an alkenyl group, a carbonyl-containing group or an alcoholic moiety. The proportions between these groups of compounds varied strongly with combustion conditions whereas the proportions of phenols within them were quite specific for each group. The phenols with reactive olefinic linkages in the sidechain were present in larger proportions than reported in other studies of methoxyphenols.
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| 5. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Methoxyphenols from burning of Scandinavian forest plant materials
- 2000
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In: Chemosphere. ; 41, s. 735-741
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Journal article (peer-reviewed)abstract
- Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg(-1) of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-1-propenyl and ethenyl groups in that position. Vanillin, 4-hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials.
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| 7. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Phenolic antioxidants in alder smoke during industrial meat curing
- 2001
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In: Food Chemistry. ; 74, s. 85-89
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Journal article (peer-reviewed)abstract
- Alder wood smoke in a large sausage-curing chamber was analysed with regard to its content of methoxyphenol antioxidants. The use of Tenax adsorbent cartridges permitted simultaneous quantitative sampling of phenols condensed on smoke particles as well as gaseous compounds. The analytical determinations were performed by thermal desorption combined with gas chromatography and mass spectrometry. In addition to methoxyphenols, several other key components were assessed, including 1,6-anhydroglucose, 2-furaldehyde, furans and hydrocarbons. Benzene was the most prominent hydrocarbon. The concentrations of polycyclic aromatic compounds were low, due to a low smoke generation temperature. Predominant smoke components were the 2,6-dimethoxyphenols, which are characteristic thermal degradation products from hardwood. The 2,6-dimethoxyphenols are stronger antioxidants than the 2-methoxyphenols present in lower amounts. The particularly active antioxidants with a 4-alkenyl side-chain constituted 20-30% of total methoxyphenols, which is much more than normally reported for liquid smoke. The phenolic antioxidants may be important not only for the preservation of foods, but also for health as dietary components.
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| 8. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Phenolic antioxidants in wood smoke
- 2001
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In: The science of the total environment. ; 277, s. 69-75
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Journal article (peer-reviewed)abstract
- Ten prominent dimethoxyphenols were determined in birchwood smoke from choked and open laboratory burning and in chimney smoke from a tiled stove. The structures of the methoxyphenols are similar to those of the well-known tocopherol and ubiquinol antioxidants. The 2,6-dimethoxyphenols characterising hardwood smoke are stronger antioxidants than the corresponding 2-methoxyphenols present mainly in softwood smoke. The antioxidant activity is highest for the 2,6-dimethoxyphenols with 4-alkenyl and 4-alkyl groups, which constitute 60-70% of the total amount of dimethoxyphenols. Phenolic antioxidants are scavengers of oxygen radicals and should be considered when health hazards of small-scale incomplete biomass burning are estimated.
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| 9. |
- Kjällstrand, Jennica, 1974
(author)
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Phenolic Antioxidants in Wood Smoke
- 2002
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Doctoral thesis (other academic/artistic)abstract
- Smoke from residential wood burning constitutes a complex mixture of organic compounds with varying environmental and health effects. This thesis focuses on antioxidants and aromatic hydrocarbons emitted from small-scale burning. Smoke samples were collected from laboratory experiments and in chimney outlets from stoves, using gas-tight syringes or adsorbent cartridges. Specific components were assessed by gas chromatography and mass spectrometry. Primary thermal decomposition products from cellulose and lignin constituted a large part of the organic fraction from incomplete combustion of wood. The lignin-related methoxyphenols are, due to their varying chemical structures, more or less effective antioxidants. Smoke from hardwood burning contained the more efficient 2,6-dimethoxyphenols, whereas softwood smoke almost only contained 2-methoxyphenols. An alkenyl or alkyl side-chain renders the antioxidant stronger, while a carbonyl group reduces the effect. The presence of phenolic antioxidants should be considered when the health hazards of wood smoke are estimated. Antioxidative 2,6-dimethoxyphenols were the predominant aromatic compounds in smoke from birchwood burning as well as from low-temperature pyrolysis of alder chips, used for meat curing. They improve both the taste and the quality of the foods. Incomplete combustion of newsprint released coniferyl alcohol as the major methoxyphenol. Newsprint is often used to set wood on fire. Methoxyphenols as well as 1,6-anhydroglucose from cellulose were released at inefficient burning. These compounds appear mainly condensed on particles at ambient temperatures. On more efficient burning, the total amount of organic compounds decreased in the smoke. However, the proportion of the hazardous polycyclic aromatic compounds increased. The carcinogenic benzene was assessed as a prominent aromatic compound in smoke from all studied types of biomass burning, although the ratio to other organic compounds increased with the combustion temperature. A comparison was made between smoke from a tiled stove and a conventional wood boiler. Stove burning released methoxyphenols and 1,6-anhydroglucose, while the boiler emitted large proportions of benzene and polycyclic aromatic compounds. Oxidative pyrolysis of wood pellets released methoxyphenol antioxidants from the flaming combustion phase. Benzene was the predominant aromatic compound from glowing pellets. New available technology for residential wood burning, including wood pellets and eco-labelled boilers, drastically decreases the emissions of antioxidants as well as hazardous aromatic hydrocarbons through highly efficient combustion.
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| 10. |
- Kjällstrand, Jennica, 1974, et al.
(author)
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Phenols and aromatic hydrocarbons in chimney emissions from traditional and modern residential wood burning
- 2001
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In: Environmental Technology. ; 22, s. 391-395
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Journal article (peer-reviewed)abstract
- The emissions from a traditional tiled stove consisted mainly of lignin-related methoxyphenols with antioxidant properties, and 1,6-anhydroglucose from cellulose degradation. A wood stove of presently introduced energy-efficient design for residential heating and hot-water supply was shown to emit small amounts of methoxyphenols and anhydrosugars from primary wood pyrolysis. Secondary harmful components like benzene and polycyclic aromatic hydrocarbons constituted a major portion of the organic emissions. It is concluded that differences in smoke composition are essential to consider in recommendations and rules for proper choices of wood burning devices.
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