| 1. |
- Ahmed, Sheikh Ali, et al.
(författare)
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Accelerated Mold Test on Dried Pine Sapwood Boards : Impact of Contact Heat Treatment
- 2013
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Ingår i: Journal of wood chemistry and technology. - : Taylor & Francis. - 0277-3813 .- 1532-2319. ; 33:3, s. 174-187
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Tidskriftsartikel (refereegranskat)abstract
- We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in ''sapwood out'' and ''sapwood in'' positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140°C, 170°C, and 200°C) for three different periods (1, 3, and 10 min). An accelerated mold test was performed in a climate chamber where naturally mold-infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides that accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth were 170°C for 10 min. However, for industrial application, the most feasible combination of temperature and time would be 200°C for 3 min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.
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| 2. |
- Akiyama, T., et al.
(författare)
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Absolute Configuration of β- and α-Asymmetric Carbons within β-O-4-Structures in Hardwood Lignin
- 2014
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Ingår i: Journal of Wood Chemistry and Technology. - : Informa UK Limited. - 1532-2319 .- 0277-3813. ; 35:1, s. 8-16
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigated the proportion of erythro-and threo-forms of beta-O-4-ether structures and their enantiomeric compositions in hardwood lignin by applying the ozonation method to birch wood meal. Optical activity was not substantially observed in either the erythronic or threonic acids obtained as the ozonation products of beta-O-4-structures in birch wood meal. The proportions of the four stereoisomeric forms {(alpha S,beta R)-erythro, (alpha R,beta R)-threo, (alpha S,beta S)-threo, and (alpha R,beta S)-erythro forms} were estimated to be 37-38%, 13-14%, 12-13%, and 36-37% based on the yields of erythronic and threonic acids, and on their optical activities. The proportions suggest that the entire components of beta-O-4-ether structures in birch wood lignin have R-and S-configurations at the beta-carbon in approximately the same quantities {(beta R)-beta-O-4-structure: (beta S)-beta-O-4structure = 50-52: 48-50}; i.e., that the beta-ether structures are essentially racemic. This estimation implies that, during lignin biosynthesis, an equal number of enantiomeric forms of beta-O-4-bonded quinone methides were formed by radical coupling reactions.
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| 3. |
- Anukam, Anthony, et al.
(författare)
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Improving the understanding of the bonding mechanism of primary components of biomass pellets through the use of advanced analytical instruments
- 2020
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Ingår i: Journal of wood chemistry and technology. - : Taylor & Francis Group. - 0277-3813 .- 1532-2319. ; 40:1, s. 15-32
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have attempted to explain forces holding particles together in densified biomass pellets using theories of forces of attraction between solid particles, forces of adhesion and cohesion, solid bridges and mechanical interlocking bonds including interfacial forces and capillary pressure. This study investigated the bonding mechanism of primary biomass components in densified pellets through the use of advanced analytical instruments able to go beyond what is visible to the naked eye. Data obtained were used to predict how primary biomass components combine to form pellets based on the theory of functional groups and the understanding of structural chemistry. Results showed that hydroxyl and carbonyl functional groups played key roles in helping to identify the type of forces acting between individual particles, at a molecular level. At a microscopic level, morphological examination of the pellet clearly showed solid bridges caused by intermolecular bonding from highly electronegative polar functional groups linked to cellulose and hemicellulose.
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| 4. |
- Blomgren, Y, et al.
(författare)
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Concentration of acid hydrolysate by reverse osmosis and mechanical vapor recompression evaporation
- 1991
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Ingår i: Journal of Wood Chemistry and Technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 11:1, s. 117-135
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this project was to investigate possible methods for the concentration of acid hydrolyzate obtained from hydrolyzing wood. A detailed study of concentration of sugar solution by reverse osmosis, RO, has been performed as well as a comparison with mechanical vapor recompression evaporation. The comparison has, in this specific case, shown that RO is currently more expensive. The result is, however, highly dependent on investment costs, and future expansion of membrane technology could mean lower area costs which would favor the technology.
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| 5. |
- Brännvall, Elisabet, et al.
(författare)
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Separate bleaching of pulp fractions enriched in earlywood and latewood fibers
- 2007
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Ingår i: Journal of wood chemistry and technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 27:2, s. 99-112
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Tidskriftsartikel (refereegranskat)abstract
- Unbleached softwood kraft pulp was fractionated in hydrocyclones into a fine fraction, enriched in earlywood fibers, and a coarse fraction, enriched in latewood fibers. The response to individual bleaching chemicals and the bleachability in bleaching sequences of the pulp fractions was studied. The light absorption coefficient, light scattering coeffient, and brightness were higher in the unbleached fine fraction than in the coarse fraction. Hydrogen peroxide managed to reduce the light absorption coefficient of the earlywood enriched fine fraction more efficiently than that of the latewood enriched fraction. In the TCF-sequence the light absorption coefficient of the fine fraction was reduced to the level of the coarse fraction at a given consumption of bleaching chemicals. In the ECF-sequence the difference in light absorption coefficient remained between the fractions. At a given consumption of bleaching chemicals, the fine fraction had higher brightness than the coarse fraction, 2%- and 1%-units on the ISO-scale in the TCF and ECF bleaching sequence, respectively.
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| 6. |
- Das, Atanu Kumar
(författare)
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Investigation of the potentiality of five bamboo species in biorefinery through analysis of chemical profiles
- 2022
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Ingår i: Journal of Wood Chemistry and Technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 42, s. 204-210
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Tidskriftsartikel (refereegranskat)abstract
- Determination of the chemical composition of biomaterial is important for their valued utilization in biorefinery. In this study, the chemical composition of five bamboo species, i.e., mitinga (Bambusa tulda), borak (Bambusa balcooa), rengoon (Thyrsostachys oliveri), orah (Dendrocalamus longispathus), and bajja (Bambusa vulgaris) were determined. The chemical characterization of these bamboo species can expedite a further study on the extraction of cellulose and lignin. alpha-cellulose content was in the range of 42.7-45.7% and Klason lignin content was 22.4-28.2%. The ash content was 1.8-4.3% for the studied five bamboo species. The alpha-cellulose and lignin content were similar to other non-timber spices. The ash content was lower than other non-timber species. Therefore, these species can be a potential source of raw material for biorefinery.
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| 7. |
- Eklund, R, et al.
(författare)
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Two-stage steam pretreatment of willow for increased pentose yield
- 1988
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Ingår i: Journal of Wood Chemistry and Technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 8:3, s. 379-392
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Tidskriftsartikel (refereegranskat)abstract
- A two-stage procedure for pretreatment of fast-growing willow with steam has been investigated. The first stage was performed at temperatures in the range 180°C to 220°C for times between 6 and 10 minutes while the second stage was performed at 220°C for 10 minutes. The fibrous material was washed between the two stages to remove the pentosans and thus increase the pentose yield. The pretreatment was assessed in terms of glucose yield and xylose yield in the subsequent enzymatic hydrolysis. The maximum yields, around 70% for both glucose and xylose, were obtained for a pretreatment temperature of 200°C in the first stage. The major part of the xylose was found in the first rinsing water while almost all the glucose was recovered from the final fibrous material. The glucose yield was increased to above 80% when wet material (30% ODM) was used in the first stage. This required a modification of the steam pretreatment unit, allowing for condensate removal during steaming. The results are very promising but further investigations are needed to optimize the process.
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| 8. |
- Gonzalo Epelde, I., et al.
(författare)
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Kinetics of wheat straw delignification in soda and kraft pulping
- 1998
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Ingår i: Journal of wood chemistry and technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 18:1, s. 69-82
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Tidskriftsartikel (refereegranskat)abstract
- Kraft and soda delignification kinetics of wheat straw, Triticum aestivum, have been studied as a function of OH- concentration, HS- concentration, and temperature. It was found that about 90% of the lignin is dissolved in the rapid initial phase. The rates of delignification in the bulk and residual phases were found to be similar to those of birch wood, Betula pubescens, The amount of residual phase lignin was found to be considerably less than in birch or spruce, Picea abies, and it was affected by the same factors, A model that accurately describes the delignification of wheat straw was derived.
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| 9. |
- Helander, Mikael, et al.
(författare)
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Parameters Affecting the Cross-flow Filtration of Dissolved LignoBoost Kraft Lignin
- 2015
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Ingår i: Journal of wood chemistry and technology. - : Taylor & Francis Group. - 0277-3813 .- 1532-2319. ; 36:1, s. 1-8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the kraft pulping process, the lignin-containing by-product kraft black liquor is currently combusted as an energy source. LignoBoost is a technique that extracts lignin from kraft black liquor, resulting in a lignin-lean black liquor, which is returned to the process, and an extracted kraft lignin. To facilitate the use of the extracted kraft lignin in high-value applications, it can be refined via fractionation to produce a more homogeneous starting raw material. Hence, the aim of this study is to investigate the behavior of dissolved softwood kraft lignin during cross-flow filtration. The effects of the lignin concentration, pH, and ionic strength on the fractionation of the dissolved lignin during cross-flow filtration are investigated. The results indicate that large amounts of low-molecular-weight kraft lignin can be produced from solutions having a low lignin concentration. Furthermore, the effects of pH and ionic strength on the fractionation of low-molecular-weight lignin are identified within the studied ranges.
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| 10. |
- Holmgren, Allan, et al.
(författare)
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Detection of pinosylvins in solid wood of Scots pine using Fourier transform Raman and infrared spectroscopy
- 1999
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Ingår i: Journal of wood chemistry and technology. - : Informa UK Limited. - 0277-3813 .- 1532-2319. ; 19:1-2, s. 139-150
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Tidskriftsartikel (refereegranskat)abstract
- Diffuse reflectance Fourier transform infrared (DRIFT) and near infrared (NIR) FT-Raman spectroscopy were used to detect pinosylvins in the wood of Pinus sylvestris L. trees. NIR FT-Raman spectroscopy offered the possibility of revealing pinosylvins simply by visual inspection of Raman spectra whereas DRIFT spectra needed a more complicated evaluation. Pinosylvin and resin acids from Scots pine were examined as to the possibility of their being the cause of observed spectral differences between sapwood and heartwood. Since pinosylvins are important compounds for the decay resistance of Scots pine wood, the detection of pinosylvins with Raman spectroscopy might be used to assess durability of wood products.
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