Research Articles

Nanocellulose (NC) was prepared from cotton linter using ionic liquid (IL) 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) as both swelling agent and catalyst followed by high-pressure homogenization. Evidence suggested that the IL played a significant role with respect to hydrolysis of the linter cellulose. The effects of various reaction conditions on the NC preparation were investigated in this study. The successful conversion of the cotton to NC was analyzed, which showed that the prepared NC had a uniform rod-like shape that was 50 nm to 100 nm in diameter and 500 nm to 800 nm in length. The characterization of the NC by X-ray diffraction and thermogravimetric analysis revealed that the crystalline cellulose I structure was retained in the NC and it showed stable thermal properties. The recycled ionic liquid exhibited a slightly decreased cellulose hydrolysis ability. The application of [Bmim]HSO4 as both a catalyst and swelling agent introduced an effective and environmentally friendly method for NC production.

Torrefaction, a thermal treatment, was studied as a means to increase calorific properties in sawdust biomass for some wooden species from southeast Europe. Torrefaction of wood material in the form of sawdust waste is known to modify the biomass at the chemical level, especially hemicelluloses. Four wood species, namely beech, spruce, larch, and oak, were thermally treated as sawdust waste at temperatures of 200 °C, 220 °C, 240 °C, 260 °C, 280 °C, and 300 °C for different times of 3 min, 5 min, and 10 min. The results indicated an increase in the calorific value and calorific density with increased torrefaction temperature and time. From the economic point of view, the pellets obtained from torrefied sawdust had better properties than untreated ones. The value-added pellets could compete on the market with traditional fossil fuels.

Maleic anhydride grafted high-density polyethylene (MAH-HDPE) film was used instead of urea-formaldehyde resin adhesive to face wood-based panels (WBP) such as finger-jointed wood panel, medium-density fiberboard (MDF), high-density fiberboard (HDF), and three-ply plywood with decorative wood veneer. The effects of hot pressing conditions on the physical-mechanical performance (surface bonding strength, water immersion performance, and hot-cold cycling performance) of overlain veneered panels were evaluated. Rheology analysis, differential scanning calorimetry (DSC), and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) were used to study the characteristics of MAH-HDPE film. Scanning electron microscopy (SEM) was used to observe the microstructure of the bonding interface. The veneered board using MAH-HDPE film as adhesive showed excellent properties, especially on water resistant and weather resistant performance. The veneered boards with finger-joint wood panel substrate could meet the Chinese national standard of type I grade veneered board of GB/T 17657 (2006), and the optimum hot pressing parameter was under a pressure of 1.3 MPa at 160 °C for 4 min. The MAH-HDPE film also can be applied to various other wood-based substrate materials for preparing veneered board. No glue penetration was observed on the surfaces.

Changes of soil biological activity and microbial diversity were assessed after application of biochar in different doses. The biochar doses were determined based on the initial carbon content in the soil, and they were increased to 2.5%, 5%, 10%, 20%, 50%, and 100% in the experimental conditions. The experiment design also included a control condition, which was not treated with biochar. The basic biological activities in the soil, i.e., enzymatic activity and the content of carbon and nitrogen in the microbial biomass, were determined. Additionally, the functional biodiversity of soil microorganisms was assessed using the Biolog EcoPlates method. It was demonstrated that biochar added to the soil at the dose of 10 to 20% significantly increased soil biological activity and functional diversity. The biochar dose of 10 to 20% was the optimal dose for enhancement of soil biological activity. This dose induced a significant increase in the total carbon content in the microbial biomass, enzymatic activity, and the overall content of total and easily extractable glomalins. The highest values of the Shannon and AWCD indices were determined in soil supplemented with 5 to 20% of biochar.

Dissolved lignin in eucalyptus black liquor was obtained at five different reaction times (1 h to 5 h) throughout the main delignification process to reveal the structural changes of lignin and its contributions to pollution load at different degrees of delignification. During the delignification process, the lignin removal efficiency and Kappa number of the pulp had a clear linear relationship with the holding time at the highest temperature (170 C). This indicated that the degree of delignification to which the pulp could be regulated by the holding time. Condensation and degradation appeared to participate as two competitive reactions in the cooking process. The condensation structures of lignin increased remarkably in the first 3 h, which resulted in increased molecular weight. Then, the degradation of lignin became the main reaction at longer reaction times (4 h to 5 h), when the β-O-4’ and β–β’ bonds were dramatically broken. Furthermore, the lignin concentration in black liquor increased with delignification time, which had a positive correlation to chemical oxygen demand (CODcr) in black liquor. The proportion of CODcr produced by lignin increased remarkably in the decomposition stage of lignin, which revealed the importance of changes in the lignin structure during the delignification process to the pollution load.

The aim of this study was to investigate the influence of cellulose sources on the physico-chemical properties of microcrystalline cellulose (MCC) for various applications. The results showed that MCC prepared from non-wood resources including cotton stalk, bamboo, and sisal was comparable to MCC made from wood in α-cellulose content, pH, moisture content, crystallinity index (CrI), and moisture sorption capacity. However, the ash content, polymerization degree, thermal stability, and mechanical properties, including tablet hardness and tensile strength, of MCC were strongly dependent upon the cellulose sources. The crystalline size (002) had no effect on the mechanical properties of the prepared MCC. The order of the obtained mechanical properties was softwood > hardwood > cotton stalk > bamboo > sisal. Compared with the less obvious variation for bamboo and sisal, the tablet hardness for wood and cotton stalk MCC noticeably decreased in correlation with increased MCC particle sizes. In addition, compared to the polycaprolactone (PCL) neat film, the tensile strength and elastic modulus of PCL/MCC films were improved by 16.0% to 42.5% and 62.7% to 82.0%, respectively.

Grape stem is a kind of agricultural and forestry waste. A fundamental understanding of grape stem pyrolysis behavior and kinetics is essential for its efficient thermochemical conversion. Thermogravimetric infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry, combined with two model-free integral methods: Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) were used to investigate the weight loss behavior, the distribution and content of rapid pyrolysis products, the release law of small molecule pyrolysis gases, and the pyrolysis activation energy during pyrolysis. The results showed that the main pyrolysis reaction temperature ranged from 240 °C to 690 °C. The pyrolysis reaction of grape stems at 200 °C to 700 °C was divided into three stages: 0.15 < α < 0.35, 0.35 < α < 0.65, and 0.65 < α < 0.75, which corresponded to the main pyrolysis stages of hemicellulose, cellulose, and lignin, respectively. The products of rapid pyrolysis at 290 °C were mainly composed of acids and sugars, while the products at 355 °C were mainly phenolics. This study aims to provide a theoretical reference for the pyrolysis gasification test of grape stem.

Engineered wood products are becoming more prevalent in the residential and commercial construction industries and need to be regulated by standards that ensure their classification and performance requirements. The applicable standard in Australia for the qualification of glued laminated timber is AS/NZS 1328.1:1998 (2011), last revised in 2011. Confusion exists with the specific interpretation of the testing procedures and subsequent methods used for the delamination process. Two methods currently used for product qualification were compared: one using a drying chamber and the other using a standard laboratory dehydrating oven. The trials conducted in accordance with the standard showed a significant difference in glue line delamination between the two testing methods. This was attributed to the lack of humidity and airflow control within the laboratory dehydrating oven and an incomplete drying of the test samples, resulting in different stresses on the glue line. It is evident that the current standard procedure requires clarification to ensure consistency in the test methods and comparable test results.

Effects of rapid cooling following pyrolysis were studied relative to the properties of activated carbon using different biomass as the raw materials. Coconut shell-based activated carbon (CSAC), bamboo-based activated carbon (BAC), and straw-based activated carbon (WSAC) were activated via high temperature and subsequently rapidly cooled to below minus 150 °C. The results showed that rapid cooling effectively increased the specific surface area, pore volume, and yield of activated carbons. Compared to natural cooling, rapid cooling increased the specific surface area of CSAC from 1076 m2/g to 1484 m2/g, increased the pore volume from 1.46 mL/g to 1.57 mL/g, decreased the average pore size from 2.25 nm to 2.13 nm, and increased the yield from 27.1% to 31.5%. The variation of the properties of activated carbon after rapid cooling using different raw materials and process conditions were studied using orthogonal experiments.

This research presents the anatomical, chemical, and mechanical properties of fibro-vascular bundles (FVBs) from two species of Salacca (snake fruit) frond: Salaccca sumatrana Becc. and Salacca zalacca Gaert (Voss). The anatomical properties were observed in the cross-section by light microscopy and digital microscopy. The anatomical observation focused on the location of the inner and outer vascular system. In the chemical analysis, FVBs were characterized for cellulose, hemicellulose, Klason lignin, and extractive content. Tensile strength and Young’s modulus were investigated, and the structural implications were considered. The FVBs from salacca frond contained vascular tissue in the cross section had new and different vascular type. Generally, the vascular tissue has a wider area than the sclerenchyma tissue. The FVBs of S. sumatrana and S. zalacca contained 41.75 and 44.60 wt% cellulose, 31.36 and 36.39 wt% hemicellulose, and 27.90 and 33.00 wt% lignin, respectively. The hot water solubility and ethanol-toluene solubility of FVBs of S. sumatrana and S. zalacca showed that extractive content were 2.96 wt% and 5.55 wt%; 18.54 wt% and 25.00 wt.%, respectively. As the diameter of FVBs increased, the tensile strength and Young’s modulus decreased. Increased FVB density will directly increase tensile strength and Young’s modulus. Based on the result, it was concluded that the FVBs of salacca type had significantly different properties compared to other palms’ FVBs, and this study confirmed the correlation between the physical and mechanical properties of the FVBs from salacca frond.