Research Articles

The potential use of residues from the logging process was evaluated for electrical energy generation by direct combustion. The findings were based on logging residues accrued from 1990 to 2015 and were enumerated using a 43% residue recovery rate. The available logging residues were insufficient to supply the primary electrical energy demand as well as reduce the emission of carbon dioxide. However, when coupled with other agricultural residues, the potential energy generation from biomass was significant and could not only lead to reduced fossil fuel demand, but also improve the carbon credit and provide additional employment opportunities in the bioenergy sector.

Copper adsorption from waste printed circuit boards (PCBs) was studied using biosorbents derived from waste orange peels (OP). The orange peels were modified by different methods including saponification with NaOH (OP-S), crosslinking with sodium trimetaphosphate and sodium tripolyphosphate (OP-C), hydroxypropylation with propylene oxide (OP-H), and acidification with citric acid (OP-A) to increase the adsorption capacity of orange peels. Adsorption tests on the copper (Cu) model solutions were performed by using native and modified orange peels at three different temperatures (25 °C, 40 °C, and 60 °C) to determine the optimum adsorption conditions. The PCB was pyrolyzed in a fixed bed stainless steel reactor to obtain a solid product that contained only inorganic material. Metals were then leached from the solid product, and adsorption studies were realized on the leach solution under optimum adsorption conditions. According to the analyses results, the best adsorption efficiency for the Cu model solution was obtained with OP-S at 25 C for 30 min. Under these conditions, the Cu adsorption efficiency from pyrolysis solid product was approximately 86%.

This study aimed to resolve the issue of the lack of detailed understanding of the effect of initial lignin content in hardwood kraft pulps on pulp delignification by deep eutectic solvents. The authors used Kappa number of the concerned pulp, intrinsic viscosity, and selectivity and efficiency of delignification as the parameters of the effect. The pulp (50 g oven dry pulp) was treated with four different DESs systems based on choline chloride with lactic acid (1:9), oxalic acid (1:1), malic acid (1:1), and system alanine:lactic acid (1:9); the results were compared to those reached by oxygen delignification. The results showed that the pulp with a higher initial lignin content had a greater fraction of easily removed lignin fragments.

This article examines the effect of selected factors (wood species, lamella combination, type of adhesive, number of loading cycles) on the impact bending strength (IBS) of laminated wood. The IBS was tested on specimens made from beech (Fagus sylvatica L.) and aspen lamellas (Populus tremula L.). The laminated wood was densified by 10% and 20% of the original thickness. For bonding the wood, polyvinyl acetate (PVA) adhesive was used, and the product was compared with laminated wood bonded with polyurethane adhesive (PUR). The wood species and lamella combination had significant effects on IBS. The highest values of IBS were found for beech wood lamellas.

To survey the anaerobic co-digestion (AcoD) of oil refinery wastewater (ORWW) with sugarcane bagasse (SCB), six different AcoD compositions were evaluated. Results including cumulative biogas production (BGP), bio-methane contents (BMP), and soluble chemical oxygen demand (CODs) removal rate were experimentally obtained. The negligible BGP by ORWW mono-digestion revealed that it could not support any microbial activity. However, increasing the SCB ratio in the AcoD compositions led to increased BGP and BMP contents. By considering the statistical test (LSD0.05) results for the kinetic parameters, the 1:4 ratio treatment was the most favorable AcoD composition. Moreover, the CODs removal rate from 22.34 ± 1.63% for the SCB mono-digestion was improved to 49.67 ± 0.38% for the 2:3 AcoD composition and BMP content from 54.12 ± 0.45% for the SCB mono-digestion was enhanced to 62.69 ± 1.22% for the 1:4 AcoD composition with 20% lower SCB usage. The results computed by applying three mathematical models determined that the modified Gompertz model provided the best fit. Also, implementing artificial neural network algorithms to model the BGP data revealed that the Back Propagation algorithm was the best suited for the experimental BGP data, with 0.6444 and 0.9658 for MSE and R2, respectively.

Soft donors of nitrogen and sulfur were incorporated into enzymatic hydrolysis lignin (EHL-NS) to make it suitable for multiple applications. Characterizations of the environmentally friendly material by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetric analysis confirmed the layered porous structure with nitrogen and sulfur groups. It exhibited high antioxidant activity due to the strong electron-donating capability of the soft donors. Moreover, the soft donors also contributed to the chemical complexation of Hg(II) with EHL-NS, which distinctly enhanced the adsorption of Hg(II) in water (Qe=180 mg/g, 25 °C). Given that the free radicals were highly effective at scavenging and adsorption, the functionalized enzymatic hydrolysis lignin is expected to serve a useful role.

Alkali-treated coir fibers were modified by silane coupling agent in a microwave oven. The use of microwave-assisted chemical treatments efficiently promoted the esterification reaction to improve the interfacial adhesion between the coir fibers and PLA matrix. Effects of the treated coir fiber content (1 wt.% to 7 wt.%) on the surface morphology and tensile, impact, and thermal properties of PLA/coir fiber biocomposites (AKWCF/PLAs) were evaluated. At a coir fiber content of 1%, the AKWCF/PLAs showed a remarkable increase of 28% in the percentage impact strength, while the tensile strength and breaking strength decreased with increasing coir fibre content. The thermal stability of the AKWCF/PLAs worsened and the degree of crystallinity increased with increasing fiber content. The decreased cold crystallization temperatures of AKWCF/PLAs further confirmed the role of coir fibers treated with the new combined method as an effective nucleating agent.

Dairy manure containing partially digested plant cells is an inexpensive bioenergy feedstock. The carbohydrates and lignin that remain after digestion are typically processed in an anaerobic digester to produce biomethane, but due to the remaining material’s recalcitrance, the process has a low conversion efficiency. To improve the conversion of this lignocellulosic material, chemical, thermal, or biological pretreatments can be considered. This study compared several chemical pretreatments including dilute acid, sulfite, and alkali pretreatments for dairy manure as a bioenergy feedstock and analyzed their impact on biomethane production. The comparative study showed that a hot alkali pretreatment (180 °C, 30 min) can improve the methane production of dairy manure by 50%, which is more effective than dilute acid (6.8%), sulfite (26.3%), and cold or ambient alkali (19.8 to 32.8%) pretreatments. However, the ambient alkali pretreatment (23 °C, 12 h) was calculated to be more economically feasible because of the net energy production.

Thermo-mechanical refining is a common fiber production process known for its high energy demands. Throughout this process, wood chips are subjected to repetitive shearing and compression such that the fibers separate and subsequently fibrillate. There is a growing body of research in the development of mechanical pre-treatments that reduce energy demands during chemo- and thermo-mechanical pulping, with shear/compression combinations currently standing as the most efficient method of initiating defibration. Given the common grounds between the fiberboard and paper refining processes, it could be possible to use paper pre-treatments during fiberboard pulp refining. Furthermore, as pulping fibers for fiberboard are less worked and refined, mechanical pre-treatments are assumed to be more efficient. In this study, the effectiveness of dynamic compression was assessed as a pre-treatment step before the chips enter the refiner. Shaped wet chips with an annual ring orientation of 45° were struck by a free-falling weight with a fixed potential energy using a special prototype. After refining both the reference and pre-treated chips using a pressurized disc refiner, the energy consumption of those fibers was 48% lower than that for non pre-treated chips for a comparable fiber quality.

The literature provides very little information about engraving or decorating wood using a laser beam. No study was found that considers the surface roughness of wood after such treatments. This paper therefore aimed to find the influence of varying the laser power output and scanning speed of a CO₂ laser beam on the surface roughness and colour of beech wood (Fagus sylvatica) for aesthetic applications such as decorative drawing. Laser power outputs from 5.6 to 6.8 W were tested in combination with scanning speeds from 100 to 500 mm/s. The surface roughness was assessed with a robust filter and by following measuring and evaluation recommendations from previous research to reduce the bias from the wood anatomy. The surface roughness measured by a series of roughness parameters (R_a, R_q, R_t, R_k, R_pk, R_vk) and total colour difference DE increased with laser power and decreased with scanning speed. A good correlation was found between surface roughness and wood colour change. Such correlations can be useful for selecting the laser power-scanning speed combinations capable of giving the chosen colour change at a minimum surface roughness.