| 1. |
- Cai, Shengzhen, et al.
(författare)
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Curing of wood treated with vinyl acetate-epoxidized linseed oil copolymer (VAc-ELO)
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine sapwood was treated with a new formulation consisting of vinyl acetate (VAc) and epoxidized linseed oil (ELO) catalyzed by potassium persulfate to impart protection to wood. The effects of various curing temperatures, durations, and solution uptakes on dimensional stability (DS) and leachability were studied. The new formulation provided good anti-swelling efficiency (ASE) ranging from 35% to 47% with negligible leaching of the treating agent after four cycles of water soaking and oven drying (2%-2.5%). The extent of polymerization in wood was observed by FTIR-attenuated total reflectance (FTIR-ATR) by evaluation of the areas below typical IR bands as a function of curing temperature and time. Linear relationships were found with high R-2 values. The FTIR data of extracted samples were interpreted that chemical reactions took place between the resulting copolymer and wood components.
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| 2. |
- Cai, Shengzhen, et al.
(författare)
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Mechanical properties and decay resistance of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate-epoxidized linseed oil copolymer
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 885-894
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Tidskriftsartikel (refereegranskat)abstract
- Equilibrium moisture content (EMC), mechanical properties, and durability of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate epoxidized linseed oil (WVA-ELO) have been studied. Microscopic observations revealed that the impregnated copolymer is mainly in cell walls, rays, resin canals, and a small fraction in the cell lumens. Under the same climate conditioning, the EMC of the treated wood was in the range of 6.0%-8.2%, which was significantly lower than that of untreated wood (about 12%). Mechanical tests performed on paired samples (control and treated) showed a slight reduction on the mechanical properties of WVA-ELO. The decay resistance against basidiomycete fungi of WVA-ELO was significantly improved as demonstrated by laboratory tests. It was found that 8% weight percentage gain (WPG) was sufficient to ensure decay resistance against the test fungi with <5% mass loss (ML), which led to durability class (DC) of 2.
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| 3. |
- Cai, Shengzhen, et al.
(författare)
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Properties of epoxidised linseed oil-furfuryl alcohol and vinyl acetate-furfuryl alcohol treated wood
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Furfurylation process is a well-studied wood modification method. Properties such as dimensional stability, decay resistance, moisture uptake and weathering have been reported to be greatly improved after treatment. However, the main remaining challenge for this process lies in the negative impact on the mechanical properties, especially the hardness which increased significantly. This has a direct impact on the structural applications of the material. In this context, new formulations consisting of combinations of furfural alcohol (FA) mixed with epoxidised linseed oil (ELO) or vinyl acetate (VA) were prepared and impregnated into Scots pine sapwood and cured without any additional crosslinking agents. Maleic anhydride was used as catalyst for polymerisation. The impact of the treatments has been studied concerning the mechanical properties, dimensional stability and durability. The average WPGs obtained after impregnation with VA-FA and ELO-FA treatments were 37.4% and 59.7% for samples intended for dimensional stability and 40.5% and 26.4% for samples intended for mechanical tests. With the achieved WPGs, the dimensional stability was significantly improved reaching an ASE of 63.3% and 43.1% for VA-FA-treated and ELO-FA-treated samples respectively. Mass loss caused by basidiomycetes fungi was in the range between 2 to 4% for both treatments, while the untreated samples lost more than 30%. MOE was almost not affected by the treatments, while impact bending strength increased by 26% after the ELO-FA treatment and decreased by 30% after the VA-FA treatment. Brinell hardness increased only by 21% for ELO-FA treatment and 64% for VA-FA treatment. These results showed that the combination of ELO with FA could result in durable timber without significant negative effect on the mechanical properties. Moreover, no darkening of the ELO-FA samples was observed.
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| 4. |
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| 5. |
- Dalahmeh, Sahar S., et al.
(författare)
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Efficiency of Iron- and Calcium-Impregnated Biochar in Adsorbing Phosphate From Wastewater in Onsite Wastewater Treatment Systems
- 2020
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the potential of biochar impregnated with Fe3+ or Ca2+, or mixed with Polonite®, as a filter material for removal of phosphate (PO4-P) from wastewater in onsite wastewater treatment systems (OWTS). Four treatments with biochar were investigated: unimpregnated biochar (UBC), biochar impregnated with iron Fe3+ (FBC), biochar impregnated with calcium oxide (CBC), and biochar mixed with Polonite® (PBC). In a batch experiment using phosphate solution at concentrations 0.5, 3.3, 6.5, 13, and 26 mg PO4-P L–1, adsorption of PO4-P in the different treatments was modeled using Langmuir and Freundlich isotherms. Column filters (5 diameter × 55 cm height) packed with UBC, FBC, CBC, and PBC were then furnished with raw wastewater over 148 weeks. During this experiment, adsorption of PO4-P was investigated in response to increasing hydraulic loading rate (HLR; 56, 74, and 112 L m–2 day–1) and increasing phosphate loading rate (PLR; 195, 324, 653, and 1715 mg PO4-P m–2 day–1). Among the materials, FBC had the highest maximum adsorption capacity (Qm) based on Langmuir isotherms (3.21 ± 0.01 mg g–1). FBC and CBC showed robust performance with increasing HLR, while increasing PLR increased the amount of PO4-P retained in all filters. After 148 weeks of operation, removal of PO4-P (averaged over the last 18 weeks of operation) was 13 ± 16% for UBC, 40 ± 20% for CBC, 88 ± 12% for FBC, and 30 ± 18% for PBC. The PO4-P amount retained in filters over the 148 weeks was 84.75, 221.75, 358.38, and 152.36 g m–2 in UBC, CBC, FBC, and PBC, respectively. The adsorption capacity of the filters after 148 weeks was 1.50, 4.02, 6.41, and 2.75 mg g–1 for UBC, CBC, FBC, and PBC, respectively. The adsorption capacity values and breakthrough curves showed that low concentrations (i.e., <2.6 mg L–1) of PO4-P in wastewater would allow the FBC filter to remain active for 58 months and the CBC filter for 15 months, before PO4-P removal declined to <70%. In conclusion, biochar impregnated with iron and calcium is a promising solution for removal of PO4-P from wastewater in OWTS.
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| 6. |
- Gao, Jie, et al.
(författare)
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Evaluation of Wood Quality Traits in Salix viminalis Useful for Biofuels: Characterization and Method Development
- 2021
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Salix (willow) is a well-known coppice plant that has been used as a source for bioenergy for decades. With recent developments in changing from a fossil-based to a circular bioeconomy, greater interest has been orientated towards willow as a potential source of biomass for transport biofuels. This has created increasing interest for breeding strategies to produce interesting genotypic and phenotypic traits in different willow varieties. In the present study, 326 genetically distinct clones and several commercial varieties of S. viminalis were analyzed using complementary approaches including density, chemical, image, histochemical, and morphometric analyses. A systematic approach was adopted whereby the basal regions of harvested stems were separated and used in all studies to aid comparisons. Density analyses were performed on all clone individuals, and from the results, 20 individual plants representing 19 clones were selected for the more in-depth analyses (chemical, image analysis, histochemical, and morphometric). The absolute dry density of the clones selected varied between ca. 300 and 660 kg/m3 with less variation seen in the commercial S. viminalis varieties (ca. 450–520 kg/m3). Selected clones for chemical analysis showed the largest variation in glucose (47.3–60.1%; i.e., cellulose) and total sugar content, which ranged between ca. 61 and 77% and only ca. 16 and 22% for lignin. Image analyses of entire basal stem sections showed presence of tension wood in variable amounts (ca. 7–39%) with characteristic G-fibers containing cellulose-rich and non-lignified gelatinous layers. Several of the clones showing prominent tension wood also showed high glucose and total sugar content as well as low lignin levels. A morphometric approach using an optical fiber analyzer (OFA) for analyzing 1000 s (minimum 100,000 particles) of macerated fibers was evaluated as a convenient tool for determining the presence of tension wood in stem samples. Statistical analyses showed that for S. viminalis stems of the same density and thickness, the OFA approach could separate tension wood fibers from normal wood fibers by length but not fiber width. Results emphasized considerable variability between the clones in the physical and chemical approaches adopted, but that a common aspect for all clones was the occurrence of tension wood. Since tension wood with G-fibers and cellulose-rich G-layers represents an increased source of readily available non-recalcitrant cellulose for biofuels, S. viminalis breeding programs should be orientated towards determining factors for its enhancement.
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| 7. |
- Gao, Jie, et al.
(författare)
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The contribution of G-layer glucose in Salix clones for biofuels: comparative enzymatic and HPLC analysis of stem cross sections
- 2022
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Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Science and Business Media LLC. - 2731-3654. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Interest on the use of short rotation willow as a lignocellulose resource for liquid transport fuels has increased greatly over the last 10 years. Investigations have shown the advantages and potential of using Salix spp. for such fuels but have also emphasized the wide variations existing in the compositional structure between different species and genotypes in addition to their effects on overall yield. The present work studied the importance of tension wood (TW) as a readily available source of glucose in 2-year-old stems of four Salix clones (Tora, Bjorn, Jorr, Loden). Studies involved application of a novel approach whereby TW-glucose and residual sugars and lignin were quantified using stem cross sections with results correlated with HPLC analyses of milled wood. Compositional analyses were made for four points along stems and glucose derived from enzyme saccharification of TW gelatinous (G) layers (G-glucose), structural cell wall glucose (CW-glucose) remaining after saccharification and total glucose (T-glucose) determined both theoretically and from HPLC analyses. Comparisons were also made between presence of other characteristic sugars as well as acid-soluble and -insoluble lignin.Results: Preliminary studies showed good agreement between using stem serial sections and milled powder from Salix stems for determining total sugar and lignin. Therefore, sections were used throughout the work. HPLC determination of T-glucose in Salix clones varied between 47.1 and 52.8%, showing a trend for higher T-glucose with increasing height (Bjorn, Tora and Jorr). Using histochemical/microscopy and image analysis, Tora (24.2%) and Bjorn (28.2%) showed greater volumes of % TW than Jorr (15.5%) and Loden (14.0%). Total G-glucose with enzyme saccharification of TW G-layers varied between 3.7 and 14.7% increasing as the total TW volume increased. CW-glucose measured after enzyme saccharification showed mean values of 41.9-49.1%. Total lignin between and within clones showed small differences with mean variations of 22.4-22.8% before and 22.4-24.3% after enzyme saccharification. Calculated theoretical and quantified values for CW-glucose at different heights for clones were similar with strong correlation: T-glucose = G-glucose + CW-glucose. Pearson's correlation displayed a strong and positive correlation between T-glucose and G-glucose, % TW and stem height, and between G-glucose with % TW and stem height.Conclusions: The use of stem cross sections to estimate TW together with enzyme saccharification represents a viable approach for determining freely available G-glucose from TW allowing comparisons between Salix clones. Using stem sections provides for discrete morphological/compositional tissue comparisons between clones with results consistent with traditional wet chemical analysis approaches where entire stems are milled and analyzed. The four clones showed variable TW and presence of total % G-glucose in the order Bjorn > Tora > Jorr > Loden. Calculated in terms of 1 m(3), Salix stems Tora and Bjorn would contain ca. 0.24 and 0.28 m(3) of tension wood representing a significant amount of freely available glucose.[GRAPHICS].
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