Research Articles

The influence of the nitrogen fertilization level was investigated relative to the chemical composition of lignocellulosic energy crops and their usefulness as a substrate for the purpose of biogas production. In the case of perennial crops, such as Virginia mallow (VM) and reed canary grass (RCG), the impacts of individual swath and cutting frequency were examined. The results showed that raised nitrogen fertilization improved the biomass quality. This was important for biogas production, primarily through decreased lignin content, and for an increased ratio of structural carbohydrates to lignin. It is believed that this tendency may facilitate the digestion of the tested substrate and increase the methane fermentation efficiency. Likewise, the swath of perennial crops differed significantly in terms of the analyzed properties, which also may have been reflected in the suitability of biomass as a feedstock for biogas plants.

Possibilities for use of thermally modified poplar veneer were evaluated for the production of plywood boards in industrial conditions. Formats of poplar veneer were treated at temperatures of 190 °C, 200 °C, 210 °C, and 215 °C for 1 h. By combining the treated and non-treated formats of veneer, thirteen different types of board were made. Analyses showed that the examined physical and mechanical properties were influenced by both the type of construction and the applied thermal treatment. Boards composed only of thermally modified veneer achieved the best results regarding moisture absorption and dimensional stability, and boards composed of the combined veneers had better mechanical properties. Treatments at 200 °C and 210 °C proved to be optimal, while the treatment at 215 °C was too harsh and should not be used for the thermal modification of poplar veneer.

The main purpose of this study was to find the optimal conditions for thermal treatment of white wood pellets. Other goals of this study were to compare torrefied and white pellets and to model the treatment process. Three types of pellets acquired from different manufacturing companies in the pellet market, representing distinct wood species, were torrefied at different temperatures of 160, 180, 200, and 220 °C, for 1, 2, and 3 h. After thermal treatment, the properties of the treated pellets were determined, including their mass loss, calorific value, ash content, and shear strength, and compared with those of the non-torrefied pellets. The calorific value increase was modeled based on the thermal degradation of hemicellulose and cellulose of the pellets and the correlation between the calorific value and mass loss. It was concluded that torrefied pellets have an increase in calorific value up to 22%, because of hemicelluloses degradation.

The adsorption of Rhodamine-B (Rh-B) from aqueous solutions onto spent mushroom substrate (SMS) and mushroom substrates prior to use (MSP) were comparatively studied in terms of the adsorption parameter effects, isotherms, and kinetics. It was found that an acidic pH of the dye solution was detrimental for basic Rh-B dye adsorption, which favored the electrostatic attraction between the cationic Rh-B and negative SMS and MSP. The adsorption isotherms of Rh-B onto the SMS and MSP followed the Langmuir model rather than the Freundlich or Temkin models. The fitted adsorption capacity of the SMS (107.5 mg/g) was approximately double that of the MSP (47.6 mg/g), which indicated a higher surface area and the presence of more adsorption functional sites that were created during edible fungus (Grifola frondosa) cultivation. Moreover, the experimental adsorption data of the SMS and MSP obeyed pseudo-second-order kinetics. The intraparticle diffusion plots revealed the multilinear adsorption nature of the SMS, which included boundary layer adsorption, intraparticle diffusion, and pore diffusion. However, only intraparticle diffusion played a major role in the adsorption of Rh-B onto MSP. It was concluded that the utilization of agricultural waste for edible fungus cultivation would not only improve the value of the agricultural waste itself, but can also remove Rh-B from aqueous solutions.

Torrefaction is a promising pretreatment process to convert biomass into high energy density solid fuel for further thermal conversion systems. In this study, the effects of wet and dry torrefaction on the properties of solid fuels prepared from bamboo and Japanese cedar were investigated in a batch reactor. The yields of solid fuels decreased with increasing treatment temperature in both torrefaction processes, mainly due to the decomposition of cellulose and hemicellulose. Cellulose showed higher reactivity than hemicellulose in both biomasses. The higher heating values (HHV) of solid fuels prepared at the treatment temperatures higher than 240 °C in both torrefaction processes reached the same level as those of commercial coals. Wet torrefaction was better than dry torrefaction for decomposing bamboo and Japanese cedar. Dry torrefaction had more favorable impact than wet torrefaction on improving the fuel properties of bamboo and Japanese cedar because of its lower energy input, higher solid fuel yield, higher energy yield, and similar HHV under the same conditions. The crystalline structure of solid fuel had no great change below 260 °C in both torrefaction processes and was completely destroyed at 300 °C during dry torrefaction.

Characteristics of the char produced in the co-pyrolysis of used rubber and larch sawdust were studied in the conversion of low-valued pyrolysis char into value-added activated carbon using two-step co-pyrolysis, namely pyrolysis and activation processes. The physicochemical characteristics of the chars were examined by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The results revealed that after the two-step co-pyrolysis, the upgraded carbon had BET surface areas ranging from 600 m2 g−1 to 900 m2 g−1, which were higher than the requirements for activated carbon (American Water Works Association B600 standard). Additionally, as the sawdust/rubber ratio increased, the BET value increased accordingly. A possible reaction mechanism is proposed based on the experimental results during the activation process.

Lignin was extracted from wheat straw and used for its crosslinking function in the synthesis of polyurethane foam (PUF). The effects of lignin’s addition on the cross-linking structure and macroscopic properties of the PUFs were investigated. A morphological examination, Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA) were conducted to measure the performance of the polyurethanes. Kinetic models were simulated to analyze the oily solvent adsorption mechanism of the polyurethane. The results showed that an increase in the cross-linking density was conducive to an improvement of the physical properties of the polyurethane. Moreover, the process of oily solvent adsorption was in accordance with the quasi-second-order kinetic model. Both physical and chemical adsorption occurred during the adsorption process. This work demonstrated a highly effective method for imparting PUFs with an excellent performance and proper lignin content.

Southern pine (Pinus spp.) wood cubes were treated with amine copper quaternary (ACQ) solutions supplemented with wax and different types of nano-SiO2 particles. The effects of various types of nano-SiO2 on the dimensional stability of ACQ-treated wood were investigated, including water absorption, swelling, and shrinkage. The results showed that nano-SiO2/wax treatments improved the hydrophobicity of the ACQ-treated wood; various types of nano-SiO2 particles had different effects on the water absorption by the wood. The best water absorption resistance was observed with the ACQ-treated wood modified with nano-SiO2 that had a specific surface area of 380 m2/g. However, the nano-SiO2/wax treatment had a negligible effect on the swelling and shrinkage resistance of the ACQ-treated wood; various types of nano-SiO2 did not affect the swelling and shrinkage of the wood.

New plywood composites for furniture and interior decoration were developed with eucalyptus veneers using polyethylene films as formaldehyde-free adhesives. To enhance the interfacial adhesion, the veneers were modified with an oven treatment (temperature: 100, 120, 140, and 160 °C; time: 0.5, 1.0, 1.5, and 2.0 h) or by soaking in a sodium hydroxide (NaOH) solution (concentration: 3%, 7%, and 11%; time: 12, 24, and 36 h). The effects of these treatments on the mechanical properties (flexural strength, MOR; flexural modulus, MOE; wet shear strength, WSS) of the composites were studied. Both treatments improved the three properties of the composites. The heat treatment was better at improving the shear property, while the alkali treatment was better at improving the flexural properties. For the heat treatment, the highest WSS was 81.1% higher than the untreated group. The optimum conditions for the heat treatment were 140 °C and 1.0 h. For the alkali treatment, the highest MOR and MOE were 267.5% and 173.7% higher than the untreated group, respectively. The optimum conditions for the alkali treatment were 3% and 36 h. The changes to the veneer surfaces were determined by scanning electron microscopy.

Emerging research on the impact of interior finishes, more specifically wood, is beginning to shed light on informed design opportunities. As a natural building material with unique features, wood creates warm and pleasant atmospheres and has the potential of enhancing the well-being of occupants. This research attempted to better understand how occupants perceive wood in built environments and whether its indoor use influenced the satisfaction of occupants. The comfort of occupants may have been influenced by factors that were unrelated to the indoor environmental quality, which caused difficulties in comparing interior finishes in existing environments and limited research in this field. An exploratory comparative study, within a post-occupancy evaluation framework, investigated the subjective perception of occupants in relation to physical comfort factors. Thirty-six occupants completed a questionnaire to examine comfort satisfaction in a multifunctional room with extensive wooden interior finishes in comparison with a similar space without wood surfaces. The results indicated that occupants were more satisfied in the extensive wood surfaced room in terms of lighting, noise, and temperature, despite the similar environmental conditions in both spaces. Adjectives often used to describe the wood room included bright, pleasant, modern, and warm. Architects should consider the subjective qualities of wood when designing comfortable buildings.