Volume 12 Issue 3

Binderless particleboards of Phoenix canariensis were manufactured by hot pressing at a low temperature (120 °C) and low pressure (2.6 MPa). Nine different configurations were analyzed to study different palm tissues. The experimental panels were tested for their mechanical and physical properties according to the procedures defined by the European Union (EN) standards. The microstructure of the raw material was investigated by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray detector for microanalysis (EDXA). The physical and mechanical behavior seemed to be influenced by the amount of parenchymatous tissue. Raw material and particle size have a profound effect on the board properties. The mechanism of self-bonding could have resulted from the high content of sugars, which were partly transformed into furfural. The use of this waste material could be beneficial to the environment because it is a method of carbon fixation, helping to decrease atmospheric CO2.

In this short communication, UV/Vis spectrophotometry is described as an analytical tool for the quantification of lignin content in deep eutectic solutions. The lignin was solubilized with different deep eutectic solvent (DES). DESs were prepared as binary mixtures of choline chloride with lactic acid (1:9); (1:10); ethylene glycol (1:2); glycerol (1:2) and alanine:lactic acid (1:9), and betaine:lactic acid (1:2). The UV-Vis spectrometric quantification of the solubilized lignins was independent of the type of solubilized lignin. The approach consists of measuring the absorbance of a solution of lignins dissolved in the deep eutectic solvents at an absorbance of 440 nm.

This study aimed to evaluate the yield and efficiency of lignin extraction from Eucalyptus grandis × Eucalyptus urophylla wood chips from treatments with sodium xylenesulphonate (SXS), and to determine their optimum conditions. First the wood’s physical, chemical, and morphological properties were characterized. Then, the wood chips underwent treatments from a combination of the following factors: time, SXS concentration, and temperature. For each treatment the yield and lignin content remaining in wood chips was determined, from which optimum points were obtained for maximum yield and lignin extraction. The physical, chemical, and morphological characterization showed that the concerned wood showed values in line with those cited in previous literature. Treatments with SXS were efficient in lignin extraction. The treatment that provided the highest calculated yield of wood was 1 h, 0%, 117.5 ºC; and the greatest lignin extraction was with 12 h, 30%, 130 ºC, removing 39.6% of lignin from wood chips. In general, the treatment of E. grandis × E. urophylla wood chips with SXS was effective in extracting lignin. However, the calculated yield and lignin extraction showed antagonistic behaviors; therefore, in light of the objectives, a careful assessment is required when using this treatment on an industrial scale to seek a balance point between the two parameters.

Wood flour-poly(lactic acid) 3D printing filaments were prepared via a melt extrusion method. Poplar wood flour and poly(lactic acid) (PLA) were used as raw materials, and different combinations of glycerol and tributyl citrate (TBC) (4% glycerol, 2% glycerol + 2% TBC, 4% TBC) were used as plasticizers. A 3D printer was used to print the filaments into standard test specimens with dimensions of 150 mm × 10 mm × 0.2 mm at the printing temperature of 220 °C. The performance of wood flour-poly(lactic acid) 3D printing filaments in terms of their interfacial compatibility, mechanical properties, melt index (MI), water absorption, and heat stability was tested under different plasticizer combinations. The results showed that under the condition of same dosage of plasticizer, the order of MI for the 3D printed filaments from high to low was 4% glycerol > 2% glycerol + 2% TBC > 4% TBC, which indicated that glycerol was more favorable for the extrusion processing of the composite filaments. However, in terms of compatibility, mechanical properties, water absorption, and thermal stability, the 3D printing filaments with 4% TBC showed better performance compared with other groups.

The demand has grown in many fields for materials that are eco-friendly and sustainably developed. In this study, several formulations of novel wood fiber reinforced ultra-high-density fiberboards (UHDFs) using resol-type phenolic resin (RTPR) as binders were manufactured for application in decorative building facades. The influences of the various formulations on water resistance and the mechanical, thermal, and fire-resistant properties were systematically examined. All formulations of the UHDFs exhibited better water resistance, internal bonding, and fire resistance as the RTPR content and density increased. To better evaluate mechanical properties, the microstructure of the UHDFs was observed using scanning electron microscopy. After optimization of hot-pressing conditions, UHDFs with excellent mechanical properties of approximately 7.2 GPa, 85.9 MPa, and 5.4 MPa for bending modulus, bending strength, and internal bonding, respectively, were achieved. Good water and flame resistance were also achieved, which makes these materials competitive with other commercial products.

Biochars are considered as promising sorbents for the removal of aqueous metal ions. The aim of this study was to explore the adsorption mechanisms through the integrated characterization of the pristine and Pb(II)-loaded biochars derived from herbaceous plant, biosolid, and livestock waste with different physicochemical properties. The biochar derived from livestock waste exhibited higher Pb sorption capacity than the others. Experimental data of sorption kinetics and isotherms were well fitted by kinetic models and Langmuir isotherm model, respectively. Comparisons of Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) between the pre- and post-adsorption biochars revealed the formation of Pb-carbonate, suggesting that the surface precipitation was the dominant adsorption mechanism. The combination of multiple characterizations and batch adsorption can make further exploration on the adsorption mechanism of Pb(II) adsorption onto the resultant biochars.

Cellulose nanowhiskers (CNW) were successfully isolated from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) through sulfuric acid (H₂SO₄) hydrolysis with different reaction times. OPEFB-MCC was hydrolyzed with 64 wt.% H₂SO₄ at 40 °C and various reaction times (30, 60, and 90 min). Effects of the hydrolysis time on the morphologies and properties of the cellulose were evaluated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The FTIR analysis showed that the chemical compositions of all of the samples were the same and represented the cellulose I structure. Hydrolysis time had little effect on the crystallinity index of the CNW, as was revealed by the XRD. The TEM images showed that the CNW produced with different reaction times had a rod-like shape and similar diameters and lengths. The produced CNW had better thermal stabilities than the OPEFB-MCC.

Outdoor bamboo-fiber-reinforced composites (OBFRCs) with four different densities were prepared, and the microstructure and physicomechanical properties of pristine samples were evaluated. In addition, the surface color, glossiness, roughness, water absorption, and wettability of the samples were tested to investigate the effects of panel density on the extent of surface weathering due to ultraviolet radiation. The results showed that the OBFRCs exhibited excellent physical and mechanical properties, which improved with increasing density. However, increases in the density led to decreases in the hygroscopicity and dimensional stability of the OBFRCs. After weathering, the surface contact angle and surface roughness increased, and the dimensional stability improved. The surface glossiness, water absorption, and surface free energy decreased. A higher density resulted in improved color stability, which suggested that density played an important role in determining surface photodegradation properties. Thus, density-increasing treatments had positive effects on the physical and mechanical properties as well as the color stability and wettability of the OBFRCs, but they may negatively affect the roughness and dimensional stability. Based on service-performance and cost-minimization considerations, 1.1 g/cm³ was determined as the most appropriate density for general applications.

Endoglucanase and lipase showed good deinking efficiency for waste papers. The performances could be greatly improved further by the combined use of the two enzymes. To reduce the enzyme production cost and enhance synergistic action of endoglucanase and lipase on laser-printed paper and newspaper, a chimeric enzyme with endoglucanase and lipase activity was constructed and expressed in Pichia pastoris. The data indicated that the chimera Lip-EG1CD improved the ink removal efficiencies and sheet brightness better than a single enzyme or a mixture of two enzymes. The chimera Lip-EG1CD demonstrated an 89% removal of toner on both papers and 91% ISO and 60% ISO sheet brightness for laser-printed paper and newspaper, respectively. Handsheet strength was also clearly improved. It revealed that the combined deinking of endoglucanase and lipase on waste papers could be strengthened by constructing proper chimera due to intramolecular synergistic action. This would be useful for developing an economical process for waste paper recycling.

A combined process consisting of an enzymatic pretreatment of small poplar wood chips, followed by an ultrasonic treatment was proposed and performed. Under the ultrasonic action of cavitation, thermal, and mechanical effects, the two processes of pulping and bleaching can be completed in one procedure. Before the ultrasonic treatment assisted pulping, an enzyme pretreatment was used to destroy the bonds between the cellulose, hemicellulose, and lignin to make the subsequent ultrasonic treatment exhibit higher selectivity and efficiency. This provided a poplar ultrasonic assisted pulp (PUP) with a 75% yield. A further analysis of the pulp, utilizing a scanning electron microscope (SEM), showed the fine fibrillation degree of the fiber surface of PUP was comparable to the traditional poplar chemimechanical pulp (PMP) and poplar chemical pulp (PCP). Thermogravimetric analysis and Raman analysis showed that the final residue obtained from the PUP was 20%. In addition, a decorative base paper was successfully made using the poplar ultrasonic pulp, and the physical properties reached or exceeded the industry standard of decorative base paper.