Bark Residues Research Articles

Optimization of Green Extraction Techniques for Polyphenolics in Pinus brutia Bark Extract and Steam Gasification of the Remaining Fraction to Obtain Hydrogen-Rich Syngas and Activated Carbon.

Utilization of renewable resources has become imperative, and considerable efforts have been devoted to tackling diverse global sustainability challenges, which contribute to the circular economy. The focus of this work was to optimize the extraction of polyphenolic compounds in Pinus brutia bark using microwave-assisted (MAE) and ultrasonically assisted (UAE) extractions and evaluate the biological efficacies of the extracts. Additionally, the residue of the extracted pine bark was subjected to steam gasification to produce hydrogen-rich syngas and activated carbon. The optimum process parameters for MAE were determined as 70 °C, 10 min, and 900 W, and 987.32 mg gallic acid equivalent (GAE), 23.7 mg quercetin/g extract, and 86.2% antioxidant activity were obtained. The optimum process parameters for UAE were determined as 70 °C, 20 min, and 50% power, and 811.84 mg gallic acid equivalent (GAE), 30.1 mg quercetin/g extract, and 90.8% antioxidant efficiency were obtained. The extracts obtained under optimized conditions were assessed for the bioactive phenolic compounds taxifolin, (-)-catechin, (-)-epicatechin, and (-)-epicatechin gallate by ultra performance liquid chromatography (UPLC). Especially in MAE (ethanol), taxifolin content was notable (34.0 mg/g extract), followed by UAE (ethanol) (23.5 mg/g extract). Compared to MAE (ethanol) and UAE (ethanol) with regards to catechin content, 1.05 mg/g extract and 0.81 mg/g extract were obtained, respectively. Catalytic and noncatalytic steam gasification of pine bark residue yielded 57.3 and 60.8 mol % H2, respectively. In addition, excellent tar reduction was achieved through utilizing a 10% boron-modified CaO alkali catalyst, and the obtained activated carbon exhibited 1358.32 m2/g Brunauer-Emmett-Teller (BET) surface area and 1.05 cm3/g total pore volume, which has potential use as an adsorbent for removing heavy metals and electrode material for supercapacitor application.

Examining the changes in the amounts of PM2.5, PM10 and CO2 in the environment in debarking operations

One of the most time-consuming stages in the production of coniferous trees is debarking the bark of the product. During debarking with a chainsaw apparatus, many air pollutants such as bark residues, dust, sawdust, fuel material, etc. are mixed into the environment. This situation reduces the air quality for the workers. This study aims to investigate the impact of the debarking process on worker health and environmental impacts in coastal pine plantations in Sarıyer region. The air pollution parameters PM2.5, PM10, CO2 and HCHO levels during the debarking process were measured using a Temtop M2000 air quality meter. The results showed that when comparing these values to standard air quality metrics, it's clear that the peak values of PM2.5, PM10, and CO2 (247 μg/m3, 411 μg/m3, and 2549 ppm) result in a "Very Unhealthy" environment. The average values for all three (83.91 μg/m3, 121.69 μg/m3, and 614.19 ppm) are classified as "Unhealthy" for PM2.5, and "Moderate" for PM10 and CO2. The study results emphasize that the log debarking process is associated with bark volume, CO2 release and PM2.5 levels. Therefore, it is vital that workers in harvesting use maximum protective equipment, especially respirators. There is also a need to raise awareness and provide training for forest workers on the use of protective equipment. These findings may contribute to the development of effective policies on the health of workers in wood production and environmental quality.

Life cycle assessment of suberin and betulin production from birch bark

In this study, the environmental impact of suberin and betulin production from birch outer bark was evaluated using life-cycle assessment (LCA), and the ReCiPe 2016 Midpoint (H) method. The system boundary includes production of outer bark to betulin and suberin production, with bark residues utilized for energy production, including all inputs (materials and energy) and outputs. Three scenarios were used to examine using the allocation, extraction and hydrolysation of birch bark. In the baseline scenario (S1), the bark came from a biorefinery and processed in a separate unit, where the hydrolysed bark residue was incinerated to generate the heat; the integrated scenario (S2) and internal loop scenario (S3) considered production within a biorefinery but with different energy sources. The primary data were collected from laboratory experiments, and secondary data were taken from the literature and the ecoinvent 3.9.1 database. FU was 2.06 kg of polymer production that includes 1 kg of suberin and 1.06 kg of betulin production from the same process. The results showed that the global warming potential (GWP) for S1 was 15.5 kg CO2 eq. per FU, 16.22 kg CO2 eq./FU in S2 and 3.96 kg CO2 eq./FU in S3. According to our results, increasing the recycling rate of ethanol (50%, 90% and 98%) in the process and using wood-based energy from the biorefinery instead of Finnish mixed electricity resulted in a significant reduction in the most important environmental impact categories except land use.

Valorization of bamboo and cedar bark residues for the production of biochars as adsorbents of CO2 and radionuclides

The escalating issues of rising CO2 emissions and radioactive pollution, specifically from isotopes like 232U and 241Am, present critical global environmental challenges. This study utilized bamboo and Japanese cedar as biomass sources for biochar production, aiming to investigate the influence of carbonization temperature on the biochars capacity to adsorb CO2 and radionuclides. The biochars were produced at 500, 600 and 700oC and underwent a comprehensive structural and material property analyses employing electron microscope, gas adsorption isotherms, and spectroscopy methods. Characterization revealed that the biochar samples predominantly consisted of micropores, whereas the Japanese cedar biochars exhibited elevated mesoporous surfaces compared to bamboo-derived biochars, along with the presence of oxygen-containing moieties on their surface. Remarkably, the results indicate a positive correlation between carbonization temperature and adsorption capacity for both CO2 and the radionuclides. Notably, biochars produced at 700 °C exhibited the highest CO2 adsorption capacity of 2.21 mmol g−1. While both bamboo and cedar biochars exhibited comparable adsorption behavior against CO2, Japanese cedar biochars demonstrated superior capacity for adsorbing 232U and 241Am compared to bamboo biochars. JC700 showed the optimum adsorption behavior, achieving 91 and 88% removal of 232U and 241Am at pH 4, respectively. These findings highlight the potential of both bamboo and Japanese cedar biochars as effective adsorbents for mitigating CO2 emissions and radioactive pollution.

Eucalyptus pellita harvest residue management in sandy tropical soils – nutrient content, decomposition and potential emissions from burning

Plantation forestry on sandy, nutrient poor soils has been developed over the last few decades in seasonally dry tropical monsoon environments. Despite the known benefits of harvest residue conservation between rotations in temperate climes, there are very few studies around the world on Eucalyptus harvest residue management in tropical areas. In Northern Australia on Melville Island 30,000-hectares of Acacia mangium is planned to be converted to Eucalyptus pellita. E. pellita harvest residues comprise high loads of stringy bark, leaves and twigs, posing a fire risk throughout the annual 6-to-8-month dry season in Australia's monsoonal tropics. In this environment, quantifying and demonstrating the anticipated benefits of residue retention is important for determining appropriate responses to fire risk.A 4-hectare experimental trial of 12-year-old E. pellita was cut with trees moved intact to the coupe edge and processed for woodchips. The tree residues from the roadside chipper were pushed back over the site. A total of 35 Mg ha−1 of harvest residue was left on the site, mainly comprised of bark (24.5 Mg ha−1 or 60 % of the total residue mass). Although the leaf and branch residues contained higher concentrations of N, Ca, Cu, K, Mg, Mn, P, and Zn than bark, stem and woodchips, bark N (51.5 kg ha−1) was twice foliage N (26.9 kg ha−1), and contributed to more than 50 % of residue N.Harvest residue bark, leaves and twigs were sampled for a litterbag decomposition study of mass loss on the harvested site. After 10 months about 80 % of bark original weight remained on site (20 % mass loss), compared to about 55 % of the leaves/twigs remaining (45 % mass loss).The potential non-CO2 emissions from the burning of E. pellita harvest residues were estimated at 12.3 Mg CO2-eq ha−1 or 3.35 Mg C ha−1, with the majority of emission arising from the smoldering of bark residues. This study discusses the implications of either retaining or burning harvest residues – for plantation long-term sustainability on sandy tropical sites, and for greenhouse gas emissions.

Effects of Supplementation of Insoluble Dietary Fiber Obtained from Cinnamon Spent Bark Waste on the Performance of Nile Tilapia (<em>Oreochromis niloticus</em>) Fingerlings

Dietary fiber supplementation has proven benefits on fish health and growth. Cinnamon spent bark waste is the cinnamon bark residue after oil distillation. It is a rich source of insoluble dietary fiber with very low contents of soluble dietary fiber. This study aimed to investigate the potential of using water-extracted insoluble fiber from cinnamon spent bark waste as a functional ingredient in the diets of Oreochromis niloticus fingerlings. Four experimental diets were prepared by replacing a commercial feed with extracted dietary fiber at 0 (control), 0.5%, 1%, and 1.5% levels. Fingerlings of O. niloticus were assigned to the four experimental diets and the feeding trial was conducted for 12 weeks. The results revealed that the weight gain, specific growth rate, feed conversion ratio, Fulton’s condition factor, and survival rate of fish were not significantly different among the experimental groups. Fiber supplementation at 1.5% significantly increased (p<0.05) the total aerobic bacteria population in feces, whereas the coliform counts in feces at 0.5% and 1% fiber supplementation were significantly lower (p<0.05) than the control. There was a significant increase (p<0.05) in red blood cells count at 0.5% fiber supplementation. Moreover, insoluble dietary fiber supplementation significantly (p<0.05) increased the white blood cell counts in blood. Results suggested that insoluble fiber supplementation affected gut microbial populations and blood parameters of O. niloticus fingerlings. However, further investigations on gut microbiology and hematology are needed to ensure the use of insoluble dietary fiber from cinnamon spent bark waste as a functional ingredient in the diets of O. niloticus fingerlings.

Obtaining of a rich-cellulose material from black wattle (Acacia mearnsii De Wild.) bark residues.

Black wattle (Acacia mearnsii De Wild.) barksare residues produced by tannin industries in huge quantities, which are normally discharged on environmental or used for energy production. Therefore, this study aimed to evaluate the use of black wattle bark residues as a raw material on obtaining of a rich-cellulose material by alkaline (MET1), acetosolv (MET2), and organosolv (MET3) procedures. The results obtained indicated that the alkaline methodology, followed by a bleaching step (MET1), promoted klason lignin and hemicellulose removals more efficiently. It was possible to observe that better results were achieved using NaOH concentration of 6% (wt%), at 65 °C for 2.5 h, presenting a yield of 63.24 ± 1.25%, and a reduction on klason lignin content of almost 90.45%. Regarding the bleaching step, it was possible to obtain a material free of non-cellulosic compounds with a yield of 78.28 ± 1.48%. Thermogravimetric analysis indicated the removal of lignin and hemicellulose as well as an increase in cellulose degradation temperature, due to changes in crystalline phases. According toX-ray diffraction (XRD), the procedures employed have led to an increase in crystallinity from 66.27 to 91.78% due to the removal of non-cellulosic compounds. Scanning electron microscopy (SEM) showed morphological alterations in accordance with the removal of non-cellulosic compounds.

Effect of tip path overlap on ring debarker performance of frozen and unfrozen black spruce logs

ABSTRACT The effect of the tip path overlap on debarking quality of unfrozen and frozen black spruce logs was studied. The power, energy consumption, and torque were also measured for both temperature conditions. The experiment consisted of debarking logs using three overlaps (8, 27, and 43%) at two temperatures (−12°C and +20°C). Debarking quality was evaluated by the proportion of bark remaining on log surfaces and by the amount of wood in bark residues. Log characteristics (dimensions, eccentricity, and knot features), bark/wood shear strength (BWSS), moisture content, and basic densities of sapwood, inner, and outer barks were measured and treated as covariates. Experiments revealed that tip path overlap affects debarking quality for both temperature conditions: the amount of bark remaining on log surfaces decreased, and the proportion of wood in bark residues increased as tip path overlap increased. In addition, the effects of bark/wood shear strength, the proportion of knot area and sapwood, inner and outer barks densities, and moisture content on debarking quality criteria were analyzed. The mean power, energy consumption, and torque increased as the tip path overlap increased. These parameters were also positively affected by the log diameter and BWSS for frozen logs. The results give helpful information to improve debarking quality within the studied range of overlaps, log characteristics, and debarking parameters with efficient energy use.

Pyrolysis temperature determines the amendment effects of poplar residue‐derived biochars on reducing CO2 emission

AbstractPoplars and their hybrids are widely planted in both plantation forestry and agroforestry systems of the world. Along with the utilization and plantation management processes, a large amount of biomass residues are produced, but the relationship between biochar properties and soil CO2 emissions is largely unknown. Here, a laboratory incubation study was conducted to assess the effects of different biochars and their corresponding biomass residues on soil CO2 emissions during the 180 days of incubation. Poplar residue‐derived biochars were larger in the surface area and total pore volume but lower in nutrients and pH values than the rice straw‐derived biochar. Increasing pyrolysis temperature led to a decrease in the total nitrogen (TN) content of poplar leaf‐ and rice straw‐derived biochars, but enhanced the TN in the poplar twig‐ and poplar bark‐derived biochars. After 180‐day incubation, the total cumulative CO2 emission decreased by 33.1%–73.8% in the biochar amendments compared to their corresponding biomass residue addition, whereas the biochars derived from poplar twig and bark residues had more positive effects on reducing soil CO2 emissions, but depended on the pyrolysis temperature. Correlation analysis showed a significant and positive correlation between the CO2 emissions and TN content of bio‐based materials but the negative relationships to total carbon content and C/N ratio. Meanwhile the positive correlations of CO2 emissions to the surface area, t‐plot micropore area, and volume of the biochars were detected. Our results suggest that application of poplar twig‐ and poplar bark‐derived biochars has a great potential for mitigating global warming.

Solid tailings after supercritical CO<sub>2</sub> extraction of lignocellulosic biomass as a source of quality biochar for energetic use and as soil improvement

Lignocellulosic biomass is a rich source of bioactive compounds that are extracted industrially from different parts of the plant. The extraction process generates residues that can contain from 75% to 95% of the raw material depending on the species. Among the many potential products of post-extraction residue’ processing there is biochar. The research objective was: i) to evaluate the parameters of biochars derived from post-extraction bark, wood and bark and wood of four lignocellulosic species; and ii) to discuss the parameters in the context of biochar functionality as an energy carrier and soil improver. The residues were subjected to pyrolysis at the three temperatures 170, 270, and 370°C, which correspond to the initiation of carbonization, and two biochars that differ in the decomposition rates of hemicelluloses, cellulose and lignin. On average, biochars had a high energy value owing to the increased content of the total and fixed carbon and calorific value by 77.0-78.4% DM, 64.6-66.7% DM and 25.8-30.1 MJ kg–1, respectively. The higher quantity of ash after processing of bark residues than wood residues implicates a lower energy value but at the same time the ash obtained is a better source of mineral compounds in the context of soil fertilization. Concerning the use of biochar as a soil improver, the biochars demonstrated lower H/C and O/C molar ratios, that indicate raised stability and resistance to the geochemical decomposition in soil. It was proven that the bark-based biochars had much higher concentrations of micro- and macronutrients as well as a higher pH, while processed wood fractions resulted in higher concentrations of total carbon and fixed carbon in biochar. The research results suggest that lignocellulose biomass extraction residues can serve as a valuable input material for production of biochar.

Willow Bark-Derived Materials with Antibacterial and Antibiofilm Properties for Potential Wound Dressing Applications.

Tree stems contain wood in addition to 10-20% bark, which remains one of the largest underutilized biomasses on earth. Unique macromolecules (like lignin, suberin, pectin, and tannin), extractives, and sclerenchyma fibers form the main part of the bark. Here, we perform detailed investigation of antibacterial and antibiofilm properties of bark-derived fiber bundles and discuss their potential application as wound dressing for treatment of infected chronic wounds. We show that the yarns containing at least 50% of willow bark fiber bundles significantly inhibit biofilm formation by wound-isolated Staphylococcus aureus strains. We then correlate antibacterial effects of the material to its chemical composition. Lignin plays the major role in antibacterial activity against planktonic bacteria [i.e., minimum inhibitory concentration (MIC) 1.25 mg/mL]. Acetone extract (unsaturated fatty acid-enriched) and tannin-like (dicarboxylic acid-enriched) substances inhibit both bacterial planktonic growth [MIC 1 and 3 mg/mL, respectively] and biofilm formation. The yarn lost its antibacterial activity once its surface lignin reached 20.1%, based on X-ray photoelectron spectroscopy. The proportion of fiber bundles at the fabricated yarn correlates positively with its surface lignin. Overall, this study paves the way to the use of bark-derived fiber bundles as a natural-based material for active (antibacterial and antibiofilm) wound dressings, upgrading this underappreciated bark residue from an energy source into high-value pharmaceutical use.

Regeneration of copper-loaded pine bark biochar using simultaneous bio-sulfide precipitation of copper

Abstract This research investigated adsorption of copper from aqueous solution onto the pine bark biochar, removal of adsorbed copper by bio-sulfide precipitation, and simultaneous regeneration of pine bark biochar adsorbent. A sulfidogenic reactor was established and operated under anaerobic conditions. During the sulfidogenic phase, COD:SO42− was gradually increased from 24:1 to 4:1. Use of sulfide-rich effluent from bio-sulfide reactor at neutral pH yielded above 99% copper removal from the aqueous solution. In the experiment's second stage, pine bark biochar was prepared through slow pyrolysis at 650 °C from pine bark residue that had a carbon content of 81% and a surface area of 368 m2/g. This biochar was then used in subsequent experiments. Initially, copper was adsorbed onto the biochar under neutral pH at contact time of 6 h. Maximum biochar adsorption capacity of 106 mg/g of copper was obtained. Finally, biochar was regenerated by precipitating the adsorbed copper as copper sulfide using sulfide-rich effluent from the sulfidogenic reactor. Complete recovery of adsorbed copper from biochar as copper sulfide precipitates were obtained was also confirmed by EDX-SEM analysis of biochar and precipitates. Regenerated biochar could be reused as an adsorbent in the subsequent adsorption cycle.

Properties and Emissions of Three-Layer Particleboards Manufactured with Mixtures of Wood Chips and Partially Liquefied Bark.

Partial liquefaction of residual biomass shows good potential for developing new materials suitable for making bio-based composites. Three-layer particleboards were produced by replacing virgin wood particles with partially liquefied bark (PLB) in the core or surface layers. PLB was prepared by the acid-catalyzed liquefaction of industrial bark residues in polyhydric alcohol. The chemical and microscopic structure of bark and residues after liquefaction were evaluated by means of Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), while the particleboards were tested for their mechanical and water-related properties, as well as their emission profiles. Through a partial liquefaction process, some FTIR absorption peaks of the bark residues were lower than those of raw bark, indicating hydrolysis of chemical compounds. The surface morphology of bark did not change considerably after partial liquefaction. Particleboards with PLB in the core layers showed overall lower densities and mechanical properties (modulus of elasticity, modulus of rupture, and internal bond strength), and were less water-resistant as compared to the ones with PLB used in the surface layers. Formaldehyde emissions from the particleboards were 0.284-0.382 mg/m2·h, and thus, below the E1 class limit required by European Standard EN 13986:2004. The major emissions of volatile organic compounds (VOCs) were carboxylic acids as oxidization and degradation products from hemicelluloses and lignin. The application of PLB in three-layer particleboards is more challenging than in single-layer boards as PLB has different effects on the core and surface layers.

Successful identification of the species of the semipetrified amber medicinal resin benzoin using molecular diagnostic technology

Benzoin is an incomplete lithified resin secreted from the trunk of the Styrax Linn. that is known as "semipetrified amber" and has been widely used in medicine due to its blood circulation-promoting and pain-relieving properties. However, the lack of an effective species identification method due to the numerous sources of benzoin resin and the difficulty of DNA extraction has led to the uncertainty of species of benzoin in the trade process. Here, we report the successful extraction of DNA from benzoin resin containing bark-like residues and the evaluation of commercially available benzoin species using molecular diagnostic techniques. By performing a BLAST alignment of ITS2 primary sequences and homology prediction analysis of ITS2 secondary structures, we found that commercially available benzoin species were derived from Styrax tonkinensis (Pierre) Craib ex Hart. and Styrax japonicus Sieb. et Zucc. of the genus Styrax Linn. In addition, some of the benzoin samples were mixed with plant tissues from other genera, accounting for 29.6%. Therefore, this study provides a new method to solve the problem of species identification of semipetrified amber benzoin using information from bark residues.

Combining Ability of Some Agronomic Characters of Sweetwaxy Double Recessive Maize Inbred Lines

The present study was undertaken to explore more excellent sweet-waxy maize germplasm resources and provide a theoretical basis for the rational application of sweet-waxy maize inbred lines. Eight sweetwaxy maize inbred lines VB. RN1621, RN1423, RN1432, RN1636, RN1441, RN1443, RN1457 and RN1669 were selected as female parents (P1) and three sweet-waxy maize inbred lines e. g. LN505, LN506 and LN515 were taken as male parents (P2). Using incomplete diallel cross NCII design, 24 combinations were configured to analyze the combining ability of eight agronomic characters such as plant height, ear height, ear grain weight, ear length, number of grains per row, hundred-grain weight, peel residue rate and amylopectin content. It was obaerved that the order of general combining ability was RN1669, RN1636 and LN506. The combination with the highest effective value of special combining ability was RN1641 × LN506, RN1621 × LN506 followed by RN1657 × LN506 which ranked third. Plant height, panicle grain weight and bark residue rate should be selected in the early generation. The ear height, ear length, 100-grain weight and amylopectin content may be selected in the late generation, which can be used for sweet-waxy maize breeding. Bangladesh J. Bot. 51(4): 849-854, 2022 (December) Special

Effect of Tool Tip Radius on ring Debarker Performance

The effects of the tool tip radius on debarking quality of unfrozen and frozen black spruce logs were studied. The power, energy consumption and torque on frozen conditions were also studied. A proto-type one-arm ring debarker was used. The experiment consisted of debarking logs using three tool tip radii (40, 180, and 300 µm) for each temperature (-20°C and +20°C). The rotational and feed speeds, tip overlap, and rake angle were kept constants. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood in bark residues (WIB). Log characteristics, used as covariates, ie dimensions, eccentricity, bark thickness, knot features, bark/wood shear strength (BWSS), basic densities and moisture contents of sapwood and bark were measured, as well as total removed material after debarking. The results showed that tool tip radius had a significant effect on debarking quality of frozen and unfrozen logs. The proportion of bark on log surfaces increased and the amount of WIB decreased as tip radius increased. At the same applied radial force, a wider tip radius showed a shallower tip penetration leaving bigger regions of bark on the log surfaces. In contrast, a narrower tip radius showed a deeper tip penetration resulting in important wood fiber tear-out. The bark thickness and inner bark MC also affected debarking quality. The mean power, mean torque, and energy consumption increased as the tip radius decreased. However, this effect will depend on the choice of the applied radial force during debarking. Motor performance was also affected by the total removed material, log diameter, and BWSS. Overall, the results highlight the importance of choosing an adequate combination of tool tip radius and applied radial force to obtain the most profitable debarking quality with an efficient energy consumption.

Cypress Wood and Bark Residues Chemical Characterization and Utilization as Fuel Pellets Feedstock

In order to meet the growing demand for raw material of solid biofuels, it is imperative to find alternative materials of low cost, underutilized so far. In this study, wood and bark material of two common cypress species (Mediterranean and Arizona cypress) were chemically characterized through gravimetric and spectroscopic (FTIR) analyses, to assess their potential to be used as raw materials in the production of fuel pellets. Low bark concentrations (0%, 2%, and 7%) were applied, and the mixtures were densified in a flat-die pellet press. The produced pellets were examined in terms of thermal, physical, hygroscopic, and mechanical properties, using standard ISO17225 thresholds as benchmark. The results revealed that the effect of bark presence in low content οn pellet properties and quality was positive. The ash content of both wood species is adequately low for biofuels production, whereas their bark cannot be purely used as feedstock due to the high ash content. By using low bark contents (2% or 7%), the ash content of pellets was kept adequately low to be categorized in the highest quality classes (A1 and A2: for residential applications), while the produced pellets demonstrated improved dimensional stability, mechanical durability, and slightly improved calorific value. The moisture content, dimensions, and bulk density of all the produced pellet categories fulfilled the standard requirements. Even though the pellets of 2% bark share presented much lower ash contents, only the pellets of 7% bark share were proven to have considerably improved mechanical durability, suitable for residential use. The chemical composition of raw materials (especially the extractives and holocellulose) plays a major role in the mechanical durability of pellets.

Factors affecting the biomass pellet using industrial eucalyptus bark residue.

Eucalyptus is utilized in the timber and paper industries. The eucalyptus bark must be peeled off during the production process, which results in a large amount of biomass residue. The objectives of this research were (i) to study the physical properties of eucalyptus bark, (ii) to investigate the crushing process using a hammer mill, and (iii) to examine the pelletizing factors of biofuel from eucalyptus bark residue using a pellet machine. Eucalyptus bark was crushed to reduce particle size and then sieved through different screen sizes (3, 4, and 5 mm) at a drum speed of 1200 rpm. The resulting eucalyptus powder was used to study the pelletizing factors of biofuel at various levels of moisture content: 17.69, 20.21, 24.27, and 26.74% w.b. and various pelletizing speeds of 250, 275, and 300 rpm. It was found that the eucalyptus powder could be pelletized at a speed of 275 rpm. Pellets with screen sizes of 3 and 4 mm could be pelletized at a moisture content of 17.69% w.b., while a screen size of 5 mm could be sued to pelletize at a moisture content of 20.21% w.b. The specific energy consumption from the particle size reduction process to the pelletizing process ranged from 667.92 to 854.64 kJ/kg. The results of bulk density, durability, and fines were 603.20–645.73 kg/m3, 96.34–96.88%, and 1.83–2.02%, respectively. The heating value was 16.19 MJ/kg. The energy value was calculated by using a eucalyptus pellet as boiler fuel (at a boiler efficiency of 38%). Eucalyptus pellets have the potential to produce energy worth 644 million THB/year or 20.6 million USD/year.

Eucalyptus Bark Residue Application for Poly(Vinyl Chloride) Composite Production: Influence of Fiber Size and Content

Background: Brazil is the world’s largest producer of short fiber cellulose, generating large amounts of eucalyptus bark residue (EBR). Aiming to obtain composites known as wood plastic composites (WPC), the effect of ground EBR addition to a poly(vinyl chloride) (PVC) matrix was studied, considering different granulometries and matrix/load proportions. The influence of fiber content addition and particle size range was analyzed in terms of mechanical and thermal properties of the PVC-EBR fiber composites obtained. Finally, by comparing these properties with those reported in the literature, the viability of EBR application as filler/reinforcement in a WPC with PVC matrix was verified. Objective: The main objective of the present study was to evaluated the influence of EBR fiber size and content in the WPC with PVC matrix, aiming to reduce the costs and improve its mechanical and physical properties. Materials and Methods: The processing method for prepared the composites were two-roll milling and subsequent hot pressing. The residue was characterized via chemical and thermogravimetric analyses, scanning electron microscopy (SEM), and aspect ratio determination. Composite evaluation involved density, tensile and flexural tests, impact resistance, heat deflection temperature (HDT), moisture absorption, and SEM of tensile fractured specimens. Results: Tensile and flexural moduli were improved with fiber addition attaining 46% and 58% increases, respectively, with better results for smaller particle size fibers; impact resistance and elongation at break, however, were reduced, attaining 48% and 5% of the control sample’s properties. SEM images reveal fiber detachment and pull-out due to their low matrix adhesion. EBR fibers cause more void formation due to low interface adhesion, which results in poor stress transference from the matrix to the fiber, in addition to EBR acting as stress concentrators in the PVC matrix; therefore, impact fracture occurs with lower energy levels. Discussion: Regions with fiber detachment and pullout from the matrix are visible, clearly demonstrating the low adhesion properties of the phases and also in accordance with the observed decrease in mechanical properties for both fibers. SEM images indicate that fibers can be considered foreign particles inside the PVC matrix, acting as stress concentrators. Also, since fibers have diameters larger than the voids caused by crazing, planar density is reduced in the direction perpendicular to chain stretching leading to low strain at break values. Composites of fiber with finer particle showed fewer voids, possibly indicating a more efficient adhesion for fibers. This could be due to a higher penetration of polymeric chains in the rugosity of finer fibers, leading to higher values of tensile strength. Conclusion: The addition of EBR content increased especially flexural and tensile moduli whilst elongation at break and impact resistance are reduced. The reduction in tensile strength due to poor fiber-matrix interfacial adhesion, though significant, allowed the use of composites with higher fiber additions. The use of EBR is coherent with the concept of circular economy. Thus, higher fiber additions relate directly to money savings since this residue costs less than PVC, and also this is an environmentally correct destination for this residue since WPC is long-term usable allowing for recycling.

Post-extraction birch bark residues as a potential binder in particleboards

Post-extraction birch bark residues as a potential binder in particleboards. Nowadays, in the wood-based composites industry, aspects such as ecology and joining the current circular economy play a very important role. However, user safety is also very important. Formaldehyde is one of the hazardous substances which, if emitted too high, can harm human health. Unfortunately, binders containing formaldehyde still reign supreme in the wood-based panels' industry. Therefore, this paper concerns the possibility of using post-extraction residues obtained during the extraction of suberinic acid, as a formaldehyde-free and ecological binder in the production of particleboards. The main component, suberinic acid, is a colorless, crystalline solid used in the synthesis of drugs and the production of plastics. The aim of the research was to answer the question: since suberinic acid itself is a good binder in the production of particle boards, as described in other publications, it is worth checking whether the post-extraction residues also have similarly good properties of joining particles in particle boards, depending on the size of the wood particles? In addition, the use of post-extraction residues of bark, and thus the elimination of synthetic adhesives in the wood-based composites production process, allows the reuse of wood raw material, which fits perfectly with the idea of upcycling. The tests showed that using post-extraction residues of birch bark, using 10% and 20% resination, the requirements of the EN 312: 2010 standard were met only in the case of the modulus of elasticity for boards made of the largest wood particles used in the tests. The resination and the size of wood particles contributed to the improvement of the properties of the tested boards.