Volume 12 Issue 1

Optimal linear wood welding parameters along the end-grain-to-end-grain faces were determined for Eucalyptus saligna, Eucalyptus pilularis, and Corymbia maculata. Joints made using Eucalyptus saligna showed a significant interaction between welding time (WT), amplitude (WA), and pressure (WP). A preheating phase of 3 s at 0.4 MPa WP and 0.75 mm WA coupled with a WT of 2 s at 2.0 MPa WP and 1.5 mm WA provided the best shear strength results of 5.1 MPa. Joints made using Eucalyptus pilularis and Corymbia maculata snapped once the holding pressure was removed, suggesting that end-grain-to-end-grain welded fibers cannot withstand the thermal stresses generated when the surface to be welded is too small (e.g., 13.5 cm2). However, grain orientation had a significant effect on the weld mechanical properties, as very strong edge-grain-to-edge-grain joints were produced with Eucalyptus pilularis and Corymbia maculata (9.5 and 6.2 MPa, respectively). The joints made of Eucalyptus saligna also showed significant improvement (7.3 MPa). Energy efficient combinations were usually those involving low WA and short WT, as WP had a marginal effect on energy consumption during the welding process.

Lignocellulosic butanol residue (BR), obtained as the by-product of lignocellulosic butanol production, was used for the preparation of lignin-based phenol-resorcinol-formaldehyde resins (LPRFRs) by condensation polymerization. The lignin was first phenolated under sodium hydroxide catalysis at 90 to 92 °C at various phenolation times (1.0 to 4.0 h). The structural differences between BR and phenolated BR (PBR) were studied using Fourier transform infrared (FT-IR) spectroscopy, ultraviolet (UV) spectroscopy, thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). The BR phenolated for 3.0 h had high phenol hydroxyl content, low molecular weight, and good thermal stability. The LPRFRs with 30 wt.% BR had the lowest free formaldehyde and phenol. With the substitution of BR for phenol, the hydrophilicity of LPRFRs increased. In addition, the mechanical, fragility, thermal properties, and morphology of lignin-phenol-resorcinol-formaldehyde foams (LPRFFs) were also investigated. The LPRFFs had excellent comprehensive properties when 30 wt.% PBR was substituted for phenol. These experimental findings could provide a new avenue for further study and application of bio-phenol-resorcinol foams.

With the purpose of taking advantage of pine sawdust residue coming from a sawmill located in Michoacán, México, a pretreatment with nitric acid and sodium hydroxide was performed. Also, the production of bioethanol by enzymatic hydrolysis was investigated. Using a response surface method, the intermediate points for the optimal HNO3 concentration were determined. Results showed that using HNO3 as a pretreatment leads to higher ethanol yields at an optimal concentration of 10.90% HNO3. After a 30-min pretreatment with 10.90% HNO3 at 114.32 °C, followed by 1% NaOH and enzymatic hydrolysis performed in shaker at a pH of 4.8 and 150 rpm for 72 h, with an enzyme loading of 25 FPU/g of total carbohydrates, the reducing sugars concentration was 99.2% (conversion of polysaccharides to monomers). On the other hand, the ethanol yield obtained from the simultaneous saccharification and fermentation treatment was 15.0 g/L, and the separate hydrolysis and fermentation was 17.1 g/L at a pH of 4.8 and 150 rpm with 1X107 Cel/mL of Saccharomyces cerevisiae and an enzymatic loading of 25 FPU/g of total carbohydrates. When comparing the results obtained with literature data, it is concluded that this procedure is suitable to exploit the lignocellulosic wastes from the Indigenous Community of San Juan Nuevo Parangaricutiro, Michoacán, Mexico.

The efficient conversion of biomass into biofuels is closely associated with the topochemistry of the cell wall. In this study, the topochemical correlation between carbohydrates and lignin in the Eucommia ulmoides cell wall was investigated in situ by confocal Raman microscopy. The carbohydrates and lignin were mainly collocated in the secondary wall of the fiber, ray parenchyma, and vessel in E. ulmoides. High carbohydrates were associated with low lignin or vice versa, indicating that a high concentration of carbohydrates leads to a drop in the degree of lignification. Furthermore, the band intensity ratio of S- and G-lignin to carbohydrates (I1333/I2889 and I1274/I2889) in morphologically distinct regions of fiber was calculated. In accordance with the wet chemical analysis, a higher ratio of lignin to carbohydrates was observed within the middle layer of the 3-year-old E. ulmoides fiber secondary wall. The results potentially extend the current understanding of the carbohydrate and lignin topochemistry in woody biomass and may facilitate an efficient wood bioconversion process in future biorefineries.

Two novel magnetic biochar composites (FeC-H and FeC-P) were synthesized using corn stalks and ferrous sulfate through hydrothermal method and traditional pyrolysis, respectively. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), vibrating sample magnetometer, and particle size analyzer. Batch experiments were conducted to investigate the ability of those samples to absorb aqueous phosphate. FeC-H had lower surface area than FeC-P, but more hydrophilic functional groups were detected on the rough surface of FeC-H. The impregnated iron was present as Fe3O4 in the prepared magnetic biochar composites. The introduced Fe3O4 resulted in high performance of magnetic separation and also played the role as adsorption sites for phosphate. FeC-H and FeC-P demonstrated higher sorption capacity than bare Fe3O4 due to the highly dispersed and smaller crystalline sizes of Fe3O4 particles loaded in corn stalk derived-biochar support. FeC-H had the best performance, with Langmuir adsorption capacity as high as 5.04 mg/g for phosphate. These results indicate that the magnetic biochar composites prepared from corn stalks by hydrothermal method (FeC-H) have potential as a high-efficiency and cost-effective adsorbent for phosphorus removal from wastewater.

Exploration of natural resources as composite fillers is still under intensive investigation. Previous works mention that nano-size natural fillers provide an alternative solution to improve certain composite properties compared with macro- and micro-size nanofibers. This work prepared biocomposites formulated from recycled acrylonitrile butadiene styrene (ABS) reinforced by nano powders or long fibers of oil palm empty fruit bunch (OPEFB). Composite properties in terms of density, Fourier transform infrared spectroscopy, surface morphology, melt flow rate, tensile strength, impact strength, and hardness were studied. The density of all composites generally increased with increasing filler loading. Composites with nano powder fillers had lesser voids than those composites with the long fiber. Melt flow rate of all composites fluctuated with filler loadings. Increasing filler loadings for composites with long fiber increased brittleness. By contrast, composites with nano powder fillers were more elastic at the higher filler loading. It was confirmed that impact and hardness properties of the composites with nano powder fillers increased with increasing filler loading. Moreover, composites with long fiber fillers decreased their impact and hardness properties with filler loadings increase.