Research Articles

Wood- (bamboo and melaleuca) and herbaceous-based (rice husk and water hyacinth) biochars, produced from local biomass by slow pyrolysis at 500 °C, 700 °C, and 900 °C, were examined for their physical and chemical properties. The wood-based biomass produced biochars with  lower ash contents (<14 wt.%_db ash) and higher fixed carbon contents (> 54 wt.%_db), greater higher heating value (>23 MJ/kg), higher degree of aromaticity (with O/C, H/C, and volatile matter/fixed carbon ratios were less than 0.08, 0.51, and 0.61, respectively), and smaller amount of salt nutrients (<76 g/kg_db) compared with those of the herbaceous-based biochars. Their unique properties have generated more interest in using them as a solid fuel, for carbon sequestration, and for soil amendment. The rice husk biochars contained more than 300 g/kg_db silica, which is potential for silicophilic plants. The water hyacinth biochars with the greatest volatile matter/fixed carbon (ranging from 0.72 to 2.35), and highest O/C ratios (0.11 to 0.18), indicating the lowest aromaticity among studied biochars and thus maybe least suitability for carbon sequestration. They also possessed a highest soluble salts content (>240 g/kg_db), highest electrical conductivity (>6489 mS/cm), and greatest liming potential (>6.56 %CaCO₃–eq), which may not be suitable for salt-sensitive plants or low-buffer capacity soils.

Chile is the second largest global producer of blueberries, which are harvested in the south-central region. As a result of the exponential production growth, a large amount of lignocellulosic biomass is generated from pruning and left on the ground as waste. As an alternative to the current incineration practices and their negative air pollution effects, this study proposed value-added utilization of these agroindustry residues. The chemical compositions (cellulose, hemicellulose, lignin, extractives, and ash) of the pruning residues from blueberry branches and trunks were analyzed. The cellulose contents from the branches and trunks were similar at 52% and 51%, respectively. However, the X-ray diffraction analysis indicated important differences in their crystallinity index, with 52% and 84%, respectively. Compared with the cellulose obtained from the trunks, cellulose from the branches was less thermally stable, possibly due to the presence of residual lignin and hemicellulose. According to the results, it is expected that the agro-industrial residues from pruning of the Chilean blueberry bushes (branches and trunks) might be of use as a potential platform for bioproducts, such as cellulose materials in order to replace synthetic or unsustainable materials.

An adhesive-free, bio-based suspended ceiling tile (nanocellulose ceiling tile (NCT)) with mildew and mold resistance, fire retardancy, and water repellence was developed and compared with commercial products (M257, M266, and M935). The NCT produced the greatest contact angle values: 145.0° (1.37% coefficient of variation (CV)) on the top surface, 137.8° (2.15% CV) on the bottom surface, and 142.2° (3.41% CV) on the edges. The thermal resistivity (R-value) of the NCT was also greater (3.14 °F∙ft2∙h/BTU (1.32% CV)), so the thermal conductivity (k-value) was lower (0.046 W/(m∙K)) than the compared commercial products (M257, M266, and M935). The NCT demonstrated resistance to mildew and mold growth, with zero defacement. Each product (NCT, M257, M266, and M935) evaluated was fire retardant, with zero horizontal flame propagation. The results showed that the NCT was an advanced ceiling tile prototype treated against fire, water, and mildew and mold growth throughout its thickness, with promising results compared to current ceiling tiles on the market.

The yield of sawn lumber has been largely governed by the identification accuracy of the external face width. However, the traditional method cannot measure the external face width with high accuracy and low error. In view of this, an image-based laser-triangulation width measurement model was established to measure the width of sawn lumber’s external face in an effort to overcome the deficiency of the traditional method. A hypothesis was established from the theoretical model, as follows: when the laser line is cast on the external face and the reflected light is captured by the camera with a certain angle, the width resolution will be the least affected and will even depend on the resolution of the camera under precise conditions. Data from contrasting experiments suggested that a particular angle has a width-detection error 0.15% and accuracy 0.177 mm, which absolutely satisfies the need of wood industry detection online. Furthermore, this paper gives a theoretical proof of conjecture from the perspective of optical principles and mathematical analysis.

Allometric equations estimating biomass and carbon stock for Acacia mangium in Malaysia have been developed. However, in previous studies they were obtained from small trials or experimental plots. In this study, models were proposed to quantify the aboveground biomass as well as the amounts of stored and sequestered carbon in two planting variants, namely second generation Acacia mangium and Acacia hybrid plantations that were approximately 10 years old. Linear, power, exponential, and logarithmic functions were fitted for aboveground biomass using trunk diameter at breast height (DBH) as the independent variable. The best fit model for estimation of total aboveground biomass was in the form of a power function y = aD^b. Application of the developed model yielded total aboveground biomasses of Acacia hybrid and second generation Acacia mangium of 113.3 Mha^-1 and 178.9 Mha^-1, respectively. This study indicated that 10-year-old second generation Acacia mangium and Acacia hybrid had sequestered 30.8 Mha^-1 and 19.5 Mha^-1, respectively, of CO₂ annually. This study showed that the Acacia mangium plantation plays a role as a carbon sink. Thus, these forest plantations benefit the economy and also mitigate carbon emissions.

Hexagonal glue-laminated timber with large cross-sections, made from small diameter logs, was studied. Effects of relative humidity variations on the moisture-induced stresses were investigated to evaluate how the prediction model compared to a real outcome. The test samples were exposed to an environment with relative humidity variations from 80% to 30%. The moisture content inside the samples was measured via X-ray computed tomography scanning. A moisture transport and a hygro-mechanical finite element simulation model was used for the prediction of moisture content and resulting stress distribution. The results from both the test and simulation showed that the moisture content in the edge angles of the samples dropped rapidly due to a large moisture diffusion rate. The moisture gradient was generated via a different moisture transfer rate at the inner and external parts of the samples. The maximum stress perpendicular to the grain in the simulation was 8 MPa and was located at the surface near the corners. This stress peak caused cracking according to the model, which was also seen in the test samples. The results for the measured moisture content agreed with the simulated results and this indicated that the moisture transfer model was adequate for simulation.

This article presents the development of a method to prepare nanocrystalline cellulose (NCCs) from laser-printed waste paper using factorial design 23 experiments by controlled acid hydrolysis of the waste paper. The method applies high gain ultrasound and subsequent flotation, washing, and bleaching stages. Characterization of the raw material, prepared pulp, test sheets, and NCCs is presented. Optimum conditions to obtain high quality NCCs were found to be 65% acid, for 40 min time of treatment, and residual load in the range of 130 to 570 mmol/kg of NCCs. The obtained NCCs were 80 to 700 nm long depending on the acid hydrolysis conditions. They exhibited high values of whiteness (90.3% Elrepho), a-cellulose contents (95%), degree of polymerization (731), viscosity (9.59 cP), and chemical compositions similar to that of Whatman paper.

The aim of this study was to investigate the effect of nanoclay on the mechanical properties of sugar palm fiber-reinforced polyester composites. Organo-modified nanoclay (OMMT) was dispersed in unsaturated polyester resin at various weight contents from 1% to 5% using a mechanical stirrer. Naturally woven sugar palm fibers were reinforced in the nanoclay-modified resin, which were then hot compressed to form the composites. The effect of the OMMT weight content on the tensile, flexural, and impact properties of the composites were analyzed. The addition of OMMT resulted in a noticeable improvement in all of the investigated properties, until a certain weight percentage. The tensile properties showed the best improvements at a 2% nanoclay content. However, the 4% nanoclay content resulted in the best enhancements to the flexural and impact properties.

Decommissioned chromate copper arsenate (CCA)-treated wood poles were subjected to a microwave liquefaction process. The liquefied products were separated into cellulosic component, lignin fractions, and spent liquor. Analysis of the distribution of the CCA elements showed that the resulting cellulosic component and lignins were detoxified. Compared with the CCA-treated wood, the fractionated detoxified cellulosic component had become micro-sized and had a higher glucan content, crystallinity, and glucose conversion yield, as well as a larger surface area.  Thus, the detoxified cellulosic component has potential as a raw material for biorefinery usage or for cellulosic material reinforced composite production. The constituents, such as glucose, xylose, glycerol, and their derivatives, as well as the metal elements in the spent liquor, are appropriate ingredients for the preparation of antifungal and insect resistant polyurethane foams. The fractionated detoxified cellulosic component and lignin products, in addition to the potential application for the spent liquor in the polyurethane industry, confirmed that the microwave liquefaction process coupled with a fractionation procedure is an environmentally conscious approach for the integrated utilization of decommissioned chromate copper arsenate treated wood.

Slow pyrolysis opened new channels for the highly efficient utilization of sunflower straw in salt-affected regions and obtained not only 28% to 40% biochar, but also 29% to 44% syngas and 29% to 31% bio-oil. Biochar yield decreased with increasing temperature, whereas syngas increased and bio-oil changed minimally. Both syngas and bio-oil had potential value as fuel. The biochar produced at 700 °C had the highest pH, ash content, and water-soluble K⁺ of 11.9, 212 g/kg, and 23.9 g/kg, respectively, and the lowest atomic ratios for H/C and O/C of 0.19 and 0.10, respectively. However, C, other minerals, surface area, and cation exchange capacity (CEC) of biochar reached a stable level at 500 °C. Therefore, the differential characteristics of the biochar derived from sunflower straw might show potential value in removing pollutants and improving soil fertility at 500 °C.