Research Articles

To improve prospects for high-value utilization of biomass, torrefaction pretreatments were conducted at 210, 230, 250, 270, and 300 °C with a reaction time of 30 min. The pyrolysis of torrefied biomass was also performed on a fixed-bed reactor system at 450 °C. The effect of torrefaction temperature on the yield, energy yield, structure, physical-chemical characteristics, and production composition of bio-oil was studied. The torrefaction pretreatment improved the fuel characteristics of pyrolysis products. When the torrefaction temperature was increased, the -OH and C=O contents decreased, the C=C contents increased, the pyrolysis peak temperature decreased, the residual carbon contents noticeably increased, and the Ea value remained in the range of 69 to 129 kJmol-1. The pore volume increased and the crystallinity index decreased due to degradation and recrystallization. The solid yield of pyrolysis biomass decreased sharply in contrast to the liquid yield. When the torrefaction temperature increased, the bio-oil yield decreased from 36.82 wt.% to 20.13 wt.%. The phenol content in the bio-oil markedly increased; however, oxygen-containing compounds such as acids, sugars, and furans, significantly decreased, which indicated that torrefaction pretreatment efficiently improved the quality of the fuel.

Phenolic-based sugar palm fibres (SPFs) were used as a filler for composites that were fabricated by hot pressing. The composites were prepared using various volume loadings of SPFs. Dynamic mechanical analysis (DMA) was carried out to evaluate the storage modulus (Eʹ), loss modulus (Eʺ), and tan delta as a function of temperature. The SPFs were treated by seawater for 30 days and a 0.5 alkaline solution for 4 days. The phenolic composites with 30% volume loading of SPFs were used to determine the effect of treatments on the DMA properties of the composites. The obtained results indicate that incorporating a SPF filler notably increased the Eʹ and Eʺ properties and decreased the damping factor of the phenolic composites. Both treatments affected the DMA results. However, the alkaline-treated composites showed higher DMA properties compared with the seawater-treated and untreated fibre composites.

The hydrothermal treatment of bamboo was carried out to investigate the effects of different temperatures (230 °C, 260 °C) and residence times (30 min, 60 min) on the combustion behaviors and properties of hydrochar. The higher heating value (HHV) increased gradually with increasing hydrothermal temperature and residence time, while the energy yield decreased. It was found that 260 °C and 30 min with a HHV of 22.8 MJ/kg and an energy yield of 57.8% were appropriate parameters for the production of hydrochar. The atomic oxygen/carbon ratio indicated that the upgrading process converted the bamboo into fuel that was similar to clean solid fuel with a high energy density. The thermal gravimetric analysis showed that the temperature and the residence time had noticeable impacts on the combustion behavior and the activation energy of hydrochar. The combustion reaction ability and rate were greatly improved when the hydrochar was prepared at temperatures greater than 200 °C. The activated energy value was determined by the model-free methods, of which Kissinger-Akahira- Sunose (KAS), Flynn-Wall-Ozawa (FWO) were the most appropriate for this purpose and resulted in similar values.

Rubberwood is an important wood resource for the wood-based industry in Malaysia and the neighboring countries in the Southeast Asian region. Many studies have been conducted to assess rubberwood’s properties and economic viability for value-added wood products manufacturing. However, information on the material’s environmental performance and green labeling is limited. Therefore, the life cycle approach was carried out in this study to evaluate the carbon footprint of rubberwood rough green sawn timber production. A cradle-to-gate approach was applied. The results indicated that the carbon footprint for rubberwood rough green sawn timber production was 52.9 CO2-eq/m3. However, when taking into consideration the carbon footprint of the whole rubberwood sawmilling industry in comparison to the Dark Red Meranti sawmilling industry, it is apparent that the total carbon footprint of the rubberwood sawmilling industry is remarkably higher. This is due to the use of inefficient processing technology, which leads to a high level of wastage on the harvesting site and in the mill. Therefore, this study shows that the green label accorded to rubberwood appears questionable from the perspective of its carbon footprint, and that efforts must be taken to minimize the waste if the material is to achieve a green material status.

The chemical, morphological, physical, and thermal properties of raw materials and single fibers extracted from different morphological parts of windmill palm were examined and comprehensively characterized after an alkali treatment. Leaf sheathes (LS) with the highest cellulose content (52.26%) achieved the most efficient extraction of fibers. Single fibers extracted from the vascular bundles of the windmill palm raw material had a slender shape with a tapering and sealing terminus, with each single fiber possessing a lumen in its cross-section. These windmill palm fibers displayed similar chemical compositions, but they exhibited significant differences in morphological parameters. Leaf blade fibers (LBFs) had the longest length (1240 μm ± 470 μm) and highest aspect ratio (121.39), which presented excellent potential as a reinforced fiber. After the alkali treatment, almost all of the hemicelluloses and lignin were removed, which resulted in increased crystallinity of extracted fibers. Thermogravimetric analysis confirmed LS stability up to 319 °C, which was higher than that of other materials from windmill palm.

The application of the wrinkle measuring method described in Müller et al. (2017) and the subsequent evaluation algorithm of a range of deep-drawn samples were used to determine the influences and interdependencies of blankholder force, tool temperatures, and drawing height on the formation of wrinkles in paperboard. The main influences were identified and quantitatively evaluated. For the given experimental space, a regression function was derived and validated in further experiments. It was shown that a quadratic regression was superior to the previously used linear regression. The findings were discussed and compared with the results of similar experiments from past publications. Special attention was given to the wrinkles formed and the resulting quality of the formed paperboard cups. The restrictions of the data acquisition from the measuring method that was used and limitations of the model were presented to demonstrate the reliability of the results.

Short rotation coppice is an option for timely procuring biomass for use as a source of energy, but it often requires the use of expensive equipment. Small-scale farmers lack the ability to purchase such equipment, but rather can use their own affordable tools. Performance of motor-manual harvesting using brush cutters in a short rotation willow coppice was evaluated by coupling traditional, Global Positioning System (GPS), and Geographic Information System (GIS) tools and methods. Strong dependence relations were found between the time effectively spent to fell willow shoots and the row length. The delay-free time consumption accounted for 81% of the total observed time, while the time spent to fell the shoots accounted for 97% of the delay-free time. The net production rate was low (0.13 ha h-1) being related to the technology used. Delays (19%) affected the performance resulting in a gross production rate of 0.11 ha h-1. Nevertheless, small-scale farmers use this level of technology in harvesting their crops by adapting the crop rotation to very short cycles, possibly to cope with technical limitations of brush cutters. The plantation system, layout, and the weather conditions may act as performance-limiting drivers. Also, adequate planning of the operational layout has the potential to increase the field performance.