Research Articles

To understand how electron beam irradiation affects wood physically and chemically, irradiated maple beams (Acer rubrum) and veneers were examined using three-point bend tests, dynamic mechanical analysis (DMA), and NIR- and FTIR- spectroscopy. The MOR from the bending tests revealed a significant decline in the red maple’s strength after a dose of 80 kGy. DMA results showed evidence of crosslinking of the amorphous content of the wood at low doses, followed by degradation at higher doses, with the change in response occurring around 80 kGy. Infrared spectroscopy revealed that the components of wood that were most impacted were the phenolic hydroxyl structures of lignin and cellulose hydroxyls, with the greatest effects being seen after 80 kGy.

Common beech (Fagus sylvatica) is one of the deciduous tree species characterized by the formation of a discolored red heart in the central part of the stem. The aim of this work was to review data in existing literature and to present original results on the extractives present in sapwood and the red heart of beech. Samples of sapwood and red heart were taken from freshly felled beech trees and extracted with a speed extractor. The content of lipophilic and hydrophilic extractives was determined gravimetrically and further evaluated by gas chromatography. The beech wood contained, on average, 1.04% lipophilic and 3.71% hydrophilic extractives. Even though the gravimetrically determined content of lipophilic extractives was comparable in the sapwood and the red heart, saturated fatty acids, fatty alcohols, and free sterols were dominant in the red heart. Sapwood contained a larger amount of total hydrophilic extractives. Mono- and oligosaccharides, sugar acids and alcohols, carboxylic acids, simple phenols, and flavonoids were identified as the prevailing hydrophilic solubles in sapwood, whereas the concentration of sugar alcohols was higher in the red heart. The composition and character of the extractives in the wood of red-hearted beech should be considered the relevant technological factor.

Activated carbon (AC) was produced via phosphoric acid (H3PO4) and zinc chloride (ZnCl2) chemical activation methods at 500 °C for 3 h. Tropical peat soil was used as a carbon precursor. The effects of activating agent concentrations on the microstructure and chemical properties of activated carbon were studied. Activated carbon with a high BET (Brunauer-Emmett-Teller) specific surface area (SBET) and a high total pore volume (Vpore) was produced using a 30% H3PO4 chemical activation method. The SBET and Vpore of the activated carbon at this condition were 1974 m2/g and 1.41 cm3/g, respectively. However, the activated carbon prepared using ZnCl2 activation only had a SBET of 794 m2/g and a Vpore of 0.11 cm3/g. The nitrogen adsorption-desorption isotherms of both activated carbons exhibited a combination of Type I and Type II isotherms, due to the simultaneous presence of micro- and mesopores structures. The microcrystallinity of the activated carbons was characterized using an X-ray diffractometer and a Raman Spectroscopy, respectively. The activated carbon produced using H3PO4 activation had higher crystalline properties than the activated carbon prepared using ZnCl2 activation. Thus, this article demonstrates the potential of tropical peat soil as a precursor of AC production.

The sanding process influences the surface morphology and chemical components of wood, which are two important factors that influence the surface free energy and wettability of wood. The objective of this study was to investigate the roughness of sanded poplar wood and the effects of sanding and aging on the surface free energy using different methods. The roughness parameter (Ra) decreased as the grit number increased, but no change was evident when the grit number increased from 120 to 240. The contact angle of water on the fresh wood samples decreased as the grit number increased. Fresh wood samples were more easily wetted by water than was the aged wood sample, and the contact angles increased as the surface roughness decreased. The surface free energy of sanded, aged wood obtained by the Zisman method may be unsuitable. For the fresh wood samples, the change of surface free energy and its components were not significantly changed when the grit number was higher than 120; for the aged wood samples, the dispersion component appeared to increase slightly as the grit number decreased. The effect of roughness on the acid/base component, acid component, and base component calculated by the vOCG method was unremarkable. The surface free energy of the wood samples (obtained using the liquid parameters provided by Volpe and Siboni (1997)) can effectively balance the relationship between the acid and base components.

The effects of atmospheric pressure dielectric barrier discharge (DBD) plasma on the surface properties of wheat straw were investigated in this work. The surface wettability changes in the wheat straw were determined using contact angle measurements, the surface morphology was observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the chemical characteristics were scanned using X-ray photoelectron spectroscopy (XPS). Moreover, the shear strength was measured using a paper tension meter. The results indicated that after plasma treatment, the urea-formaldehyde (UF) resin had lower instantaneous and equilibrium contact angles on the wheat straw surfaces than the untreated specimens did, which decreased by 34% and 64%, respectively. Obvious etching was observed on the wheat straw surface after plasma treatment. There was an increase in the O/C ratio along with an increase in the C2, C3, and C4 proportions based on the XPS analysis after plasma treatment on wheat straw surface. Moreover, the shear strength between glued surfaces of the wheat straw was greatly improved after plasma treatment, indicating that atmospheric pressure DBD plasma treatment was an effective method for improving the surface properties of wheat straw, which were helpful for UF resin penetration and application of wheat straw.

Based on the steam explosion pretreatment that has been applied to other types of lignocellulosic biomass, the steam explosion pretreatment of bamboo, along with a study of the chemical compositions and enzymatic hydrolyzability of substrates, was conducted. The results show that steam explosion pretreatment can greatly enhance the cellulose-to-glucose conversion yield after enzymatic hydrolysis, which is sometimes affected by bamboo age and steam explosion conditions. When the steam explosion pretreatment conditions were 2.0 MPa (pressure) and 4 min (time), the cellulose-to-glucose conversion yield of 2-year-old bamboo substrate was 62.5%. However, the cellulose-to-glucose conversion yield of bamboo substrates after direct (without steam explosion pretreatment) sodium chlorite/acetic acid delignification was 93.1%. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 88.1% to 96.2% of the corresponding theoretical ethanol yield after 24 h.

Fibre morphology and its evolution during refining and fractionation at low consistency were studied to understand the key relationships between the mechanical properties of paper and those of fibres. A broad analysis is presented on the physical and mechanical properties characterising the intrinsic morphological properties of fibres. The experimental refining process involved a primary stage at high consistency (HC), a fractionation stage with a small aperture basket, a low consistency (LC) refining stage, and a final high consistency refining (HCR) stage. The idea was to benefit from the pulp already being at low consistency following the screening step. Using a higher proportion of low consistency refining (LCR) tended to lower the tensile strength at 100 mL CSF, but some intermediate values did exhibit better responses to refining. Fractionation permits the use of LCR to retain fibre length and to develop additional long fibre bonding. The net gain remains even with energy reduction. It is believed, among other things, that a greater number or greater intensity of fibre-to-bar contacts would help increase internal delamination of the fibre structure.

The Camellia oleifera oil industry is the economic mainstay in many high-poverty mountain regions of China, but the defatted seeds are currently discarded, leading to a waste of bioresources. In this work, a cost-effective technique was designed to isolate the flavonoid, saponins, and polysaccharides by ultrasonic-assisted acid-base alternative extraction. The activities of these compounds were evaluated by their DPPH and ABTS radical scavenging abilities in vitro and inflammatory inhibition in mice, and the economic efficiency was assessed. The optimal extraction conditions by response surface design were 1.6% HCl, water/seed ratio 16, extraction time 89 min, and ultrasonic power 310 W. The yields of the flavonoid, saponin, and polysaccharide were, respectively, 1.4 ± 0.2%, 6.7 ± 0.8%, and 22.5 ± 1.7%. The extracts could eliminate DPPH and ABTS radicals and alleviate inflammation with concentration dependence, and showed excellent capacity in the order of flavonoid ≥ saponin > polysaccharides. The residue after extraction was cellulose, with a yield of 63.0 ± 2.4%. The defatted seeds could produce a value of $11.35 per kilogram after production of the four valuable extracts, which would greatly increase the income in these high-poverty areas. This integrated extraction technique provides valuable recycling utilization of a typically discarded bioresource.

In this study, two purified mild acidolysis lignins (MAL) extracted from triploid poplar, i.e., Alcell MAL and Alkali MAL, were compared. Some properties, including elemental contents, higher heating value (HHV), functional hydroxyl group compositions, and molecular weights, were tested to characterize the structure of these two MALs. The releasing laws of gases and the distribution of products were also investigated through the use of thermogravimetric Fourier transform infrared (TG-FTIR) and pyrolysis-gas chromatography combined with mass spectrometry (Py-GC/MS). The results showed that both MALs had pyrolytic advantages, largely because of their unique chemical structures. However, although the species of volatiles from Alkali MAL were similar to those from Alcell MAL, the releasing temperature range for Alcell MAL was relatively narrow and the volatiles from it were concentrated. Among the fast pyrolytic products, phenols were the most abundant. The yield of 2,6-dimethoxy-4-(2-propenyl)phenol, which was the dominant product, was 25.66% for Alcell MAL and 20.77% for Alkali MAL, respectively. Overall, pyrolytic products from Alcell MAL were more enriched.

Extraction of lignin from lignocellulosic materials in an autoclave using 1,4-butanediol medium has been examined by researchers. However, there has been no research on the extraction of lignin in a 1,4-butanediol medium at atmospheric pressure and no extraction of HBS lignin from wheat straw has been investigated. In this paper, lignin was isolated from wheat straw in 1,4-butanediol media (from 50% to 100%, v/v) that was catalyzed by H2SO4 or NaOH while refluxing under atmospheric pressure. Reaction time, liquid-solid ratio, the volume percentage of 1,4-butanediol, as well as catalysts were optimized to improve the lignin yield. The optimum extraction conditions were: 12-to-1 liquor-to-straw ratio of 80% 1,4-butanediol, 1.67% of H2SO4 or 0.83% of NaOH, and 3 h reaction time. The optimum yield of lignin was found to be 60.64%. Analysis with Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetry showed that the lignin obtained using the NaOH catalyst had fewer unconjugated C=O groups, fewer =C-O-C bonds, lower molecular weight, and was more thermally unstable than lignin obtained using the H2SO4 catalyst.