Research Articles

Poplar (Populus tomentosa Carr.) solid wood was surface densified in the tangential direction, and the vertical density profile (VDP) and hardness of the treated and untreated samples were measured. The effects of the process parameters on the VDP and hardness were investigated. To explicitly describe the VDP of the surface densified wood, five indices (AD, ADx, PD, PDi, and DTh) were used. The compressing temperature and closing speed influenced the formation and shape of the VDP. A higher temperature yielded a greater PD and Pdi, and a faster closing speed yielded a higher PD, but smaller PDi and DTh. Increasing the compression ratio increased the AD, ADx, and maximum load, and the poplar wood was compressed in the overall thickness as the compression ratio exceeded a certain degree. The Janka hardness of the poplar wood was significantly improved after surface densification; a higher temperature resulting in a higher surface hardness was explained by the higher PD. The closing speed and compression ratio affected the hardness by impacting the VDP, specifically the PD and DTh indices. When the PD and DTh were greater the surface hardness was greater. By this study, a compressing temperature of 140 to 160 °C and the closing speed of 10 mm/min is recommended, and to prevent the deformation of unheated side of the wood samples and obtain a higher surface hardness, the compression ratio is restricted to 20%.

Increasing the profitability of lignin side-streams is a challenge in the scientific community. Lignin residue originates from black liquor and lignin cake, which are residues from pulp and bio-ethanol production. This paper presents a life cycle assessment study to investigate how pulp and bio-ethanol processes vary in their environmental performance when a fraction of lignin is removed and to identify the best alternative energy source. Fossil energy, natural gas, and cogeneration were evaluated as heat and power alternative sources. The results showed that lignin removal does not considerably affect the environmental performance of the baseline systems and does not generate a relevant risk of “burdens shifting.” Natural gas was the best alternative of power source in a bio-ethanol system, whereas cogeneration showed better compatibility with pulp mills. For the analyzed systems, the necessary allocation distributed the impact contributions between the main products (bio-ethanol/pulp) and the co-products (lignin-cake/black liquor), counterbalancing the impact increase due to the introduction of the new heat, electricity supply, and additional treatment aimed at lignin extraction. Finally, sensitivity analyses confirmed the low influence on the results of the substitution ratio.

The process of removing chromium(III) ions from aqueous solutions was investigated with respect to a phosphorus-containing product containing inositol hexaphosphoric acid derivatives obtained from rice bran-rice waste products of Far Eastern breeding varieties. The removal efficiency of chromium(III) ions by phosphorus-containing product depended on their initial concentration and reached 82%. Thus, environmentally friendly polyfunctional chelate materials from rice production wastes could be used to remove metal ions from aqueous solutions.

A one-step, liquid-phase hydrogen peroxide reaction system, which was heterogeneously catalyzed by KBr-doped graphitic carbon nitride (KBr/g-C3N4), was developed for the conversion of furfural to maleic acid (MA). At first, a 68.0% MA yield was achieved in a homogeneous reaction system catalyzed by KBr-KOH. Next, a series of K-doped g-C3N4 catalysts with various potassium salts (KBr, KCl, KNO3, and KOH) was synthesized and tested for the conversion of furfural to MA, 2-buten-1,4-olide (FRO), and succinic acid (SA). When comparing the various K-doped g-C3N4 catalysts, KBr/g-C3N4 enhanced MA selectivity, which resulted in complete furfural conversion and a 70.4% MA yield (at 100 °C for 180 min). Furthermore, a synergistic interaction was observed between KBr and the g-C3N4 support, which could explain why KBr/g-C3N4 had the highest MA selectivity.

Construction systems based on cross-laminated timber (CLT) have versatility in material development and are an interesting alternative for construction. This study evaluated the structural performance of cross-laminated timber-bamboo produced from wood (Pinus spp.) and bamboo (Dendrocalamus giganteus). Panels were produced by strips (wood and bamboo) assorted, under non-destructive structural grading, to support a better panel configuration. Small-length pine pieces were also included in the study, considering their low added-value and underutilization in sawmills from Telêmaco Borba, Brazil. Gluing tests of small specimens were performed to evaluate the bonding quality of three adhesives: melamine-urea-formaldehyde (MUF), isocyanate polymeric emulsion (IPE), and castor oil-based resin (COR). Shear stress strength parallel to grain between bamboo and wood showed the best performance for MUF resin. After preliminary gluing testing, eight cross-laminated panels were produced with MUF adhesive in a three-layered configuration, with transversal orientation: two external bamboo layers and a central layer of pine wood. Stiffness and rupture strength values were above those specified by the ANSI/APA PGR 320 (2012) standard. Elasticity and rupture moduli were 13,310 MPa and 65 MPa, respectively, showing good potential of this composite for structural uses.

Feasibility was studied for the manufacture of glulam sleepers using wood sleepers that had been discharged or sold at low prices by railway companies. In principle, an engineering recycling project of this nature could contribute to the reduction of non-renewable natural resource extraction. The manufacturing stages of glulam recycled wood sleepers are shown. Ultrasonic tests were used for the classification of the wood sleepers’ parts and wood strength optimization. The results showed that it was possible to obtain one wood sleeper from the recycling of four or five used sleepers.

Wood-based panel applications recently have expanded and become increasingly competitive, especially within the furniture and civil construction industries. To remain competitive, such products must present physical properties that meet consumer needs. In this context, the incorporation of nanomaterials is gaining momentum, mainly as a means to improve the physical characteristics of panels, thereby expanding their applications. The aim of this study was to evaluate the physical properties of medium density particleboard (MDP) panels after adding various proportions of nanocellulose in place of water to the urea-formaldehyde (UF) adhesive in MDP panel production. The results showed that the addition of nanocellulose resulted in no significant statistical difference in the density and moisture content of the panels. When tested for thickness swelling, only the panel with 100% nanocellulose solution exhibited a significantly higher value. The panels were subjected to scanning electron microscopy (SEM) analysis, which showed that the addition of nanocellulose led to a more polished, less irregular surface. Such physical effects of nanocellulose can potentially make panels more suitable for coating applications. The feasibility of coatings on nanocellulose MDP panels can be verified through future tests to determine the surface roughness of the panels.

Experiments were carried out with a new method for assessing an updraft gasification reactor. An attached side door enabled the investigation of zone development by stopping air supply at specific times, when the thickness of biomass, char, and ash layers were measured. Development in zone thicknesses of biomass, char, and ash with time associated with temperature distribution provided information about the speed of flame propagation inside the reactor. Initially, pyrolysis and volatile combustion occurred, as evidenced by the high mass loss rate and high growth rate of the char layer. Shrinkage in the char layer took place later, and this phenomenon was governed by char glowing, which was relatively slow in mass loss rate. Finally, the fully developed char layer was obtained. The results from four different air mass fluxes under updraft configuration were presented, showing the differences in layer development. Temperature profiles at each time step revealed that the location of peak temperature coincided with the location of ash-char interface for every air mass flux. This effect was due to the high energy release during the oxidation of fixed carbon.

This study investigated the feasibility of an environmentally friendly incense consisting of a soy-based adhesive and miscellaneous wood powder (MWP). Key properties, such as water absorption, burning speed, density, and tensile strength, were examined. The suitable adhesive usage amount for the preparation of incense was 31.8%. When the soy-based adhesive contained 3% polyvinyl alcohol (PVOH), the water absorption, burning speed, density, and tensile strength of the incense were 24.6%, 13.93%, 0.713 g/cm3, and 1.01 MPa, respectively. Incense made of soy-based adhesive with PVOH displayed a higher tensile strength and decreased moisture resistance. The denser structure and even distribution of the MWP was observed via scanning electron microscopy of the incense with soy-based adhesive modified by 3% PVOH. When paraffin wax was added with the MWP, the incense had a higher moisture resistance, but the effects on the tensile strength were negligible. A combination of PVOH-modified soy-based adhesive, paraffin wax, and MWP was found to be suitable for preparing an environmentally friendly incense.

The release of fermentable monosaccharides from cellulose is a key step for the economical and efficient production of ethanol from lignocellulosic biomass. However, some residual substances in pretreated biomass negatively affect enzymolysis by reducing the activity of the enzyme due to the nonproductive and competitive binding of enzymes. To improve enzyme efficiency, heterologous proteins have been introduced as an additive for cellulase during the hydrolysis process. In this study, the enzymatic hydrolysis of cellulose from pretreated bamboo was enhanced by adding an aqueous extract of the bamboo to the hydrolysis system. The cellulose to glucose conversion yield (CGCY) increased to different extents when different substrates were used with different enzyme loadings. The promotional effect of bamboo extractives on enzymatic hydrolysis of different bamboo varieties was observed. In conclusion, the deactivation of the cellulolytic enzyme by negative binding to residual lignin in substrate was reduced due to the competitive effects of proteins in the extract. In addition, other effects, such as easy accessibility of the substrate (amorphogenesis), were also possible reasons. Overall, the promotional effect of bamboo aqueous extractives played an important role in the enzymatic hydrolysis of pretreated bamboo.