Volume 17 Issue 4

Lignin is a renewable natural aromatic polymer that is generated as a co-product during lignocellulosic biorefinery processes, and it has been applied widely as a functional biomaterial. In this study, the adsorption behavior of Cd(II) and Pb(II) metal ions was investigated via ion chelation using aminated lignins (ALs) with primary, secondary, and tertiary amine groups. ALs exhibited optimal Cd(II) and Pb(II) adsorption capacities in solution under neutral conditions due to their chelating, electrostatic, and cationic–π interactions with metal ions. The AL with the primary amine group showed the highest adsorption capacities for both Cd(II) and Pb(II), reaching 83.2 and 159.7 mg·g-1, respectively, followed by the ALs with secondary and tertiary amine groups. The adsorption kinetics and isotherm analysis demonstrated that all adsorption behaviors followed the Langmuir isotherm and pseudo-second-order kinetics. Thermodynamic studies revealed that the adsorption processes of Cd(II) and Pb(II) using the ALs were spontaneous and endothermic. These results demonstrate that ALs are promising adsorbents for the removal of Cd(II) and Pb(II) metal ions.

Discrete element simulation parameters of the tail stem and tail leaves of crushed sugarcane tail leaves (STL) were calibrated by a combination of physical experiments and simulation optimization design. First, the values or ranges of the basic physical parameters and contact parameters of crushed STL were measured using physical tests, and the results were used as the basis for the selection of the simulation parameters. Plackett-Burman testing was applied for the significance screening of the initial parameters. Then, the error values and significant parameters of stacking angle for the second-order regression models were obtained using the steepest ascent experiment and the Box-Behnken optimization test. An analysis of variance (ANOVA) was also performed. Finally, using 37.52° stacking angle of physical test as the validation target, the optimal combination of parameters was obtained: coefficient of static friction (COSF) for tail stem-tail stem of 0.45, COSF for tail leaf-tail leaf of 0.38, coefficient of rolling friction (CORF) for tail stem-tail stem of 0.14, and CORF for tail stem-tail leaf of 0.12. The error of stacking angle obtained from the simulation and the physical tests was 0.976%, which verifies the reliability of the optimal parameters.

Intumescent coating was studied relative to the fire performance of nail-laminated timber. Three NLT specimens were coated with three different intumescent coating thicknesses (1, 2, and 3 mm) in even-numbered laminae and compared to uncoated NLT specimens. As a result of the coating, the internal temperature of the coated specimen increased more slowly than that of the uncoated specimen. The average charring rate of the intumescent coating specimen was reduced by 12.8% (1-mm thickness), 14.1% (2-mm thickness), and 15.4% (3-mm thickness) compared with the uncoated specimen. However, statistical analysis showed there was no significance between 1-, 2-, and 3-mm coating thicknesses. The combustion of wide surfaces of timber laminae between the plywood was delayed due to the coated plywood, and the timber laminae became a one-dimensional charring rate problem. Therefore, if even laminae are coated with an intumescent, then the NLT can be designed with a one-dimensional charring rate condition.

This study examined the flexural behavior of the poplar laminated veneer lumber (LVL) box floor with orthogonal rib beams. Four 3.6 m × 4.8 m box floor samples made of poplar LVL orthogonal rib beams and oriented strand board (OSB) plates were tested under vertical uniform loading, from which the bearing capacity, stiffness, and failure characteristics were analyzed. There was no damage in all box floor samples at the normal service load of 2.5 kN/m2, and the maximum deflection was far less than the allowable value. When the maximum load was applied, the load-displacement curve of each floor sample exhibited a linear relationship without obvious failure. However, localized failure was manifested as the dislocation slip of the rib beams relative to the upper and lower floor slabs at the corner nodes and the joint expansion and staggered floors at the bottom plate, with obvious failure signs. The rib beam height had the most significant impact on the floor stiffness, followed by the spacing of short-side rib beams, whereas the OSB plate thickness had lest impact. The mid-span deflections of poplar LVL orthogonal ribbed box floor samples, which were calculated using the analog slab method, were in good agreement with the experimental results with an error being less than 10%.

Thermoplastic elastomer composites based on ethylene vinyl acetate (EVA), natural rubber (NR), and Mengkuang leaf fibre were prepared using the sulfur and peroxide vulcanization systems. Different curing systems and fibre loadings affecting the processing torque, tensile, thermal, and morphology of the composites were investigated. Addition of Mengkuang leaf fibre resulted in poor fibre dispersion and agglomeration in the matrix, which may have affected the efficiency of stress transfer and thus could explain a decline in tensile and thermal properties. Composites with dynamic vulcanization showed a rougher surface that might be due to the presence of crosslinking, which requires more force to fail. The increase in stabilization torque for the composites with dynamic vulcanization was observed due to the addition of curing agents, which implies some changes at the molecular level due to crosslinking. Tensile properties of Mengkuang leaf fibre filled EVA/NR composites indicated that the tensile strength, elongation at break, and Young’s modulus of the peroxide cure system were higher than the sulfur cure system and unvulcanised composites. The sulphur cure system showed better resistance towards thermal degradation compared to the peroxide cure system. This was attributed to dicumyl peroxide (DCP), which degrades the polymer chain or the composites at high temperature.

Toxic organic dyes present in wastewater should be removed before discharge. In this study, TEMPO-oxidized, regenerated cellulose beads were prepared using a simple falling ball technique for cationic methylene blue (MB) removal. The obtained cellulose beads were characterized using various analytical techniques. The results indicated that TEMPO-oxidized cellulose beads displayed porous structures with high content of carboxylic acid groups. Thus, the negatively charged cellulose beads can effectively adsorb cationic MB with an adsorption capacity of 495 mg/g at a starting concentration of 100 mg/L. This simple one-step adsorption process achieved near-complete MB removal at pH 7, indicating strong electrostatic interactions between cationic MB and negatively charged oxidized cellulose beads. The experimental data can be well described by the Langmuir isotherm model and the Pseudo-second-order model. The fabricated cellulose beads exhibit great potential for practical application in dye removal from wastewater.

Friction profilometry is a powerful technique that is suitable for the surface characterization of paper products. In this technique, a stylus-type contact method that resembles papermaking processes is used for evaluating the quality attributes of products. The surface characterization requires both surface roughness and friction measurements. At present, however, few reports have been available regarding characterization of the friction by the surface profilometric method. The objective of this study was to provide guiding principles of a stylus-type contact surface profilometry for determining the friction properties of paper. Another objective was to introduce the concept of the mean absolute deviation (MAD) from the average coefficient of friction as a new friction parameter.

Large quantities of lignin are produced as by-streams via chemical pulping and emerging biorefinery processes. These lignins are typically water-insoluble; however, they can be converted into a water-soluble form by chemical modifications. A novel LigniOx technology solubilizes lignin using alkali-O2 oxidation. The product can be used for bio-based dispersants. This study evaluated the biodegradability of alkali-O2 oxidized kraft, organosolv, and hydrolysis lignin. The oxidized lignins exhibited higher biodegradation in soil and in aquatic environments in comparison to a commercial kraft lignin and a commercial lignosulfonate. In soil, the biodegradabilities of oxidized lignins were 19 to 44%, whereas the reference lignins exhibited only 5 to 12% conversion to CO2. Biodegradation of the oxidized lignins and references in the aquatic environment increased in a similar order as in the soil environment, although the degradation in each sample was slightly smaller than in the soil. The improved biodegradability of the oxidized lignins was due to the altered chemical structure of lignin. Compared to the untreated lignin, the oxidized lignin contained structures formed in aromatic ring opening reactions, making the lignin more accessible to microbial degradation. In addition, the oxidized lignin contained carbon originating from small organic compounds, which are easily biodegradable.

Eucalyptus is a fast-growing and high-yield tree species producing approximately one third of the timber of the world. Eucalyptus leaves are a by-product of timber with comparable biomass, and are largely unused. Eucalyptus leaves are rich in polyphenols, of which oenothein B is the most abundant. In this study, the authors developed an ultrasonic-based method for extracting oenothein B from Eucalyptus leaves. The ethanol concentration was proven to be a key determinant for the extraction efficiency and quality of oenothein B. Extracting with an ethanol concentration greater than 20% resulted in the altered chemical structure of oenothein B. The optimized conditions for Oenothein B extraction from Eucalyptus leaves used 10% ethanol and a 1 to 50 (g/mL) material to liquid ratio for 1 h under 40 kHz ultrasonic at a temperature of 87 °C. The highest extraction yield obtained was 12.4%. The oenothein B extract showed the capability of reactive oxygen scavenging. The accumulation pattern of oenothein B during the developmental processes of Eucalyptus leaves was detected using the developed method, and the rapid-accumulation period of oenothein B was determined, which will facilitate the utilization of Eucalyptus leaf resources.

Dalbergia tonkinensis is very similar to Dalbergia odorifera in material, texture, and other macroscopic characteristics, and a comparison of the commonalities and differences in the chemical composition of the extractives may help to distinguish the two. However, the chemical composition of Dalbergia tonkinensis heartwood is unknown. The total flavonoid content of Dalbergia tonkinensis heartwood was determined to range between 49.67 to 101.95 mg, which indicated that Dalbergia tonkinensis is as equally rich in flavonoids as Dalbergia odorifera. Thirty-one flavonoids were identified via ultra-performance liquid chromatography-mass spectrometry in Dalbergia tonkinensis. Among them, the contents of 15 medicinal active flavonoids with were determined, and the liquiritigenin, naringenin, formononetin, pinocembrin, and biochanin A contents were found to be high. The 12 volatile compositions of Dalbergia tonkinensis heartwood identified via gas chromatography-mass spectrometry were very similar to those of Dalbergia odorifera and were dominated by trans-nerolidol, caryophyllene oxide, and eudesmol. The relationship between the chemical composition of Dalbergia tonkinensis and Dalbergia odorifera heartwood extracts was determined via a principal component analysis, and the results indicated that there was no significant difference in chemical composition between the two. This suggested that Dalbergia tonkinensis could be used as a potential substitute for Dalbergia odorifera.