Treesearch

Equilibrium moisture content (EMC) was measured over a range of relative humidities at 22.5°C to determine whether certain wood preservatives increase the hygroscopicity of southern pine (Pinus sp.) The treatments studied were alkaline copper quaternary (ACQ) at a retention of 6.6 kg•m−3, chromated copper arsenate (CCA) at 6.9 kg•m−3, and disodium octaborate tetrahydrate (DOT) at 3.8 kg•m−3 (equivalent to 2.6 kg•m−3 as B2O3). All treatments examined increased the EMC at relative humidities above 60 %.Wood treated with DOT was the most hygroscopic. At high relative humidities, the ratio of...

A theoretical model was developed to better understand the process of microwave explosion treatment of wood cells. The cell expansion and critical conditions concerning pressure and temperature of ray parenchyma cells in Eucalyptus urophylla were simulated during microwave pretreatment. The results indicate that longitudinal and circumferential stresses were generated in the cell walls owing to the internal steam pressure during extensive microwave treatment. The circumferential stress is twice as high as the longitudinal stress. The pressure difference reaches its maximum value of 0.84...

This study investigated the effects of chemical pretreatment and disk-milling conditions on energy consumption for size-reduction and the efficiency of enzymatic cellulose saccharification of a softwood. Lodgepole pine wood chips produced from thinnings of a 100-year-old unmanaged forest were pretreated by hot-water, dilute-acid, and two SPORL processes (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) at acid charge on oven dry (od) wood of 0% and 2.21%. The pretreated wood chips were then milled using a laboratory disk mill under various solids-loadings and disk-plate...

This review presents a comprehensive discussion of the key technical issues in woody biomass pretreatment: barriers to efficient cellulose saccharification, pretreatment energy consumption, in particular energy consumed for wood-size reduction, and criteria to evaluate the performance of a pretreatment. A post-chemical pretreatment size-reduction approach is proposed to significantly reduce mechanical energy consumption. Because the ultimate goal of biofuel production is net energy output, a concept of pretreatment energy efficiency (kg/MJ) based on the total sugar recovery (kg/kg wood)...

Two new methods based on FT–Raman spectroscopy, one simple, based on band intensity ratio, and the other using a partial least squares (PLS) regression model, are proposed to determine cellulose I crystallinity. In the simple method, crystallinity in cellulose I samples was determined based on univariate regression that was first developed using the Raman band intensity ratio of the 380 and 1,096 cm-1 bands. For calibration purposes, 80.5% crystalline and 120-min milled (0% crystalline) Whatman CC31 and six cellulose mixtures produced with crystallinities in the range 10.9–64% were used....

Lodgepole pine from forest thinnings is a potential feedstock for ethanol production. In this study, lodgepole pine was converted to ethanol with a yield of 276 L per metric ton of wood or 72% of theoretical yield. The lodgepole pine chips were directly subjected to sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) pretreatment and then disk-milled; the recovered cellulose substrate was quais-simultaneously saccharified enzymatically and fermented to ethanol using commercial cellulases and Saccharomyces cerevisiae D5A. The liquor stream from the pretreatment containin...

Fibres that acquire a z-direction tilt in the forming process help bond adjacent strata of the paper sheet, increasing z-direction shear. Fibre tilt manifests itself as a measurement difference when directionally sensitive tests are conducted “toward headbox” or “toward reel.” Seven of eight different paper grades ranging in grammage from 73 to 268 g/m2 were found to show this difference for Scott-internal-bond tests, directional-brightness tests, or both. Test results were compared for 180° rotations in the machine direction and cross-machine direction. Three-eights of the rotations...

Cellulose degradation by brown rot fungi, such as Postia placenta, is poorly understood relative to the phylogenetically related white rot basidiomycete, Phanerochaete chrysosporium. To elucidate the number, structure, and regulation of genes involved in lignocellulosic cell wall attack, secretome and transcriptome analyses were performed on both wood decay fungi cultured for 5 days in media containing ball-milled aspen or glucose as the sole carbon source. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a total of 67 and 79 proteins were identified in the extracellular...

Cellulose nanocrystals (CNCs) are gaining interest as a “green” nanomaterial with superior mechanical and chemical properties for high-performance nanocomposite materials; however, there is a lack of accurate material property characterization of individual CNCs. Here, a detailed study of the topography, elastic and adhesive properties of individual wood-derived CNCs is performed using atomic force microscopy (AFM). AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs under ambient conditions with 30% relative humidity...

Brown rot basidiomycetes initiate wood decay by producing extracellular reactive oxygen species that depolymerize the structural polysaccharides of lignocellulose. Secreted fungal hydroquinones are considered one contributor because they have been shown to reduce Fe3+, thus generating perhydroxyl radicals and Fe2+, which subsequently react further to produce biodegradative hydroxyl radicals. However, many brown rot fungi also secrete high levels of oxalate, which chelates Fe3+ tightly, making it unreactive with hydroquinones. For hydroquinone-driven hydroxyl radical production to contribute...