Research Articles

A novel method was introduced to evaluate the quality of fiber material from paper for recycling. The new concept, fiber integrity value, its components, and its relationship with paper strength properties were examined in more detail. The effect of deinking and screening on fiber integrity value, and its component parameters was shown. The fiber integrity value is closely connected to the strength potential of the pulp. It was shown that when the bonding degree was also considered, there was very good correlation with the tensile strength, tensile stiffness, and compressive strength (SCT) values. The fiber integrity value concept can be determined based on data from in-line analyzers.

Interest in the use of beech as a raw material in engineered wood products for structural purpose has increased in Europe, in particular laminated veneer lumber (LVL). Indeed, this kind of product has exhibited superior mechanical properties with a lower variability compared to solid wood. This study investigated the influence of the forestry management system (e.g., high forest versus coppice) and of the veneer defects (e.g., knots and joints) on the mechanical properties of beech laminated veneer lumber (LVL) beams. The research included the measurement of modulus of elasticity and bending strength of 40 LVL beams (50 x 50 x 1200 mm3). Bending strength and modulus of elasticity of beam made from high forest wood compared to coppice wood were respectively higher by 20% and 12%. The impact of natural and manufacturing-process defects on the bending strength was studied using an X-ray imaging system. Defects in the inner layer of LVL beams were detected via X-ray. The defects produced by the manufacturing process itself had an effect on the bending strength similar to the natural defects of wood.

Chemical constituents of naturally decayed Qinghai spruce branches were analyzed in terms of holocellulose, lignin, and pentosan. The holocellulose content declined from 57.98% to 35.29% in one year. The rate of change may be related to weather conditions, i.e., the rate of variation was higher when the temperature was high and rainfall was abundant. The changes in lignin and pentosan relative content were completely different from holocellulose; they increased first and then decreased during the decay period. Compared with fresh raw materials, pentosan content (from 14.44% to 25.9%) was increased by 79.4% after four months decay. The highest yield of furfural (10.2%) prepared by a two-stage method from decayed Qinghai spruce branches was similar to the reported yield from corncobs.

The objective of this study was to establish the stress-strain empirical mode of oriented strand board (OSB) with random surfaces and oriented core 0° pattern (R/0°/R). The OSB specimens were loaded along the longitudinal (0°), diagonal (45°), and transverse (90°) directions of plates. The loading direction had a significant effect on the behavior of OSB. The OSB in compression exhibited high non-linear elastic behavior up to failure, while it expressed linear behavior when loaded in tension. Four types of failure modes under compression were included: end cracks between flakes, central cracks between flakes, diagonal shear failure, and surface folding. Most of the specimens in tension failed in tensile failure suddenly without plastic deformation. A refined empirical model was suggested and found to be in good agreement with the experimental data. The results provided useful information for modeling various structures containing OSB.

In 2017, a carbon emissions trading market will be launched nationwide by the China government. Calculating the enterprise carbon emissions is an important prerequisite and basis for trading. This paper discussed types of greenhouse gases, calculation boundaries and methods, energy consumption, carbon emissions, and intensity of a representative integrated pulp and paper mill in China based on China Guidance and Greenhouse Gas Protocol Tools. The results showed that there were 435,000 tonnes (t) of CO2 emissions from that mill in 2014 that did not contain emissions of biomass energy, which was 8 times higher than that of fossil energy. The pulp carbon intensity based on the mill was 0.230 t CO2/Adt, which accounted for 7.50% to 57.4% in other pulps’ based on the product. Intensity based on Gross Domestic Product (GDP) was 1.090 t CO2e/1000 USD and accounted for 56.8% intensity in the China paper industry. The intensity based on sales accounted for 52.6% in the first-class enterprise in the developed country. It also showed that intensity was influenced by the species of raw material, energy, and products, which provided the mill with measures for energy saving and emissions reduction to obtain the redundant carbon emissions in the trading.

A new type of wood-plastic/lumber composite (WPLC) was fabricated with laminated veneer lumber as a core, and the traditional wood-plastic composite (WPC) as a shell layer using multi-phase co-extrusion technology. This WPLC was used to manufacture a window frame, and the effects of inorganic pigments (carbon black (CB), titanium dioxide (TiO2), and their mixtures) on the decorative effect and ultraviolet (UV) weathering performance of the shell layer of the window frame were investigated. Weathering variables included UV irradiation duration and water spraying cycles for up to 6000 h. The surface color was analyzed by spectrophotometry during weathering. In addition, a scanning electron microscopy analysis and Fourier transform infrared spectroscopy analyzed the weathering properties of the WPLC shell layer. The results showed that (1) different decorative effects (white, grey, and black color) of the window frames were achieved by incorporating CB, TiO2, and their mixture; (2) the composites incorporated with CB and/or TiO2 exhibited less discoloration and fewer surface cracks; (3) the composites with CB and TiO2 showed a better photo-stability than those with a UV stabilizer (UV326). The overall color change (△E) of the composites incorporated with UV326, TiO2, and CB was 20.0, 11.7, and 10.8, respectively, after 3000 h of weathering; and (4) a combination of CB and TiO2 showed a synergistic effect on alleviating the photo-oxidation process of the WPC shell layers, which confirmed its UV-shielding effect.

A multi-enzymatic biopreparation of Trichoderma atroviride G79/11 origin was characterized. The fungus showed relatively high cellulase production in a soybean flour-cellulose-lactose medium. Subsequently, based on its post-culture liquid, the biopreparation of the enzyme mixture was developed and characterized. The liquid form of the enzyme mixture reached 22 U cm-3 of cellulolytic activity and its lyophilisate exhibited 1.09 U cm-3 at pH 5.1 and 50 °C. The enzyme mixture was characterized by the following activities: xylanase, β-glucosidase, carboxymethyl cellulase, polygalactouronase, pectinesterase, amylase, lactase, and protease. A method for an efficient conditioning process of organic waste (fruit processing waste, dairy sewage sludge, corn silage, and grain broth) for biogas yield enhancement using the enzyme mixture was proposed. The enzyme mixture increased the efficacy of biogas production by 30% when the lyophilizate (0.5 mg g-1 d.m.) was applied prior to fermentation. A method for conducting the enzymatic conditioning process of organic waste using the enzyme mixture as a pretreatment was proposed. This was part of the optimization of the methane fermentation process to increase the biogas yield. Consequently, after application of the biopreparation, the efficiency of anaerobic digestion of organic waste was improved.

This study aimed at developing an operational high-pressure steam pretreatment (HPSP) to effectively modify rice husk for enzymatic saccharification. The HPSP was performed at 160 to 200 °C under 0.3 to 2.8 MPa for 2 to 10 min. The efficiency of this method was based on the chemical composition, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses. Optimum pretreatment conditions (200 °C, 1.85 MPa for 7 min), enzyme concentration at 30 FPU/g and temperature at 60 °C for 48 h of continuous saccharification effectively produced sugar (21.1 g/L = 0.422 g/g dry substrate) at a saccharification degree of 53.87%. Conducting a second-step enzymatic saccharification resulted in additional sugar production (7.9 g/L = 0.158 g/g substrate) and a 20.44% saccharification degree. In contrast, the two-step saccharification process (48 and 24 h) achieved optimal sugar yield of 0.581 g/g substrate and saccharification degree of 73.5%. Additionally, the process improved the yield of monomeric sugars of glucose (0.465 g/g), xylose (0.010 g/g), and cellobiose (0.063 g/g). Therefore, the combination of the high-pressure steam pretreatment with thermostable cellulase from Bacillus licheniformis 2D55 in a two-step enzymatic saccharification process is an economically viable method in rice husk bioprocessing for sugar production.

N-doped microporous activated carbons were synthesized by hydrothermal doping with ammonia as the nitrogen precursor; the chemical, structural, and hydrogen storage properties of the developed activated carbons (ACs) were also examined. The results showed that this method is an effective way of preparing microporous activated carbons with high surface area. Both the surface areas and the N contents of ACs were increased after hydrothermal doping, and hence, the hydrogen storage capacities were improved. The hydrogen storage capacity of the N-doped ACs was 3.10 wt.% at 77 K and 1 bar, showing an enhancement factor of 1.13 and corresponding to the NAC with both highest surface area (3485 m²/g) and N content (2.2 wt.%). Statistical analysis showed that both the N content and surface area had positive contributions to the hydrogen storage, and it also could be predicted by the linear model from the N content and surface area. These results were among the best in hydrogen storage carbon materials, and the high hydrogen storage capacities were attributed to the high surface area.

Electron beam irradiation (EBI) was used to improve the reactivity of bamboo dissolving pulp. An EBI treatment with a dose lower than 10 kGy showed that the Fock reactivity of the dissolving pulp noticeably increased from 69.5% to 98.3% with negligible cellulose losses.  However, when the irradiation dose was higher than 10 kGy, the Fock reactivity increased with an observable α-cellulose loss, which could result in the lower strength of end-products. The gradual increase of Fock reactivity has a good agreement with the reduction of the degree of polymerization (DP) of cellulose. This suggests that lowering the DP of cellulose could enhance cellulose reactivity. Later analyses confirmed that an EBI treatment creates fiber pores that facilitate a cellulose xanthation reaction. The EBI treatment could randomly destroy cellulose crystalline and amorphous regions. The results indicated that the reactivity improvement was due not only to the DP, but also due to the changes in the fiber morphology and cellulose structure caused by the EBI processing.