Research Articles

Composite films with different Kappaphycus alvarezii seaweed and corn starch concentrations were developed, and the effect of these concentrations on the films’ optical, mechanical, and water vapor barrier properties were investigated. The chemical interactions between the two components in the film were verified by chemical composition and Fourier transform infrared (FTIR) spectroscopy investigations. The results showed that the mechanical properties and opacity of the composite films were enhanced with the addition of seaweed. Among the compositions, a composite film with 3% seaweed and 1% starch exhibited the highest tensile strength and elongation at break. The water vapor permeability (WVP) of the composite films linearly increased with the increments of starch and seaweed concentrations. The FTIR analysis also revealed intermolecular interactions between the two components, consistent with the good miscibility of seaweed and starch in the blend. Therefore, different concentrations of the blend of seaweed and starch could be used to tailor a film with certain desired functional properties.

Effects of various surface modifications were evaluated relative to the mechanical properties of sugar palm fiber/glass fiber (SPF/GF) reinforced thermoplastic polyurethane (TPU) hybrid composites. The 6 wt.% alkaline, 2 wt.% silane, and combined 6 wt.% alkaline-2 wt.% silane treatment of SPF were carried out for 3 h to improve the fiber/matrix interaction of SPF/GF with TPU. The SPF and GF were fixed at 30 wt.% and 10 wt.% fiber loading, respectively, and were fabricated using the melt compounding method followed by hot compression in a moulding machine. Mechanical properties, such as tensile, flexural, and impact strength, were evaluated using a universal testing machine and an Izod impact tester. The untreated and treated hybrid composites were characterized by FTIR spectroscopy. The tensile, flexural, and impact strength of the combined 6 wt. % alkaline-2 wt. % silane treatment was improved 16%, 39%, and 18%, respectively, as compared to the untreated SPF/GF reinforced TPU hybrid composites. Moreover, the scanning electron microscopy (SEM) showed a good fiber and matrix interfacial bonding in the hybrid composites. Thus, this treated hybrid composites could be suitable for fabricating automotive parts.

5-Hydroxymethyl furfural (5-HMF) was prepared using microcrystalline cellulose as the raw material, an ionic liquid as the solvent, and ethyl butyrate as the co-solvent. The decomposition of microcrystalline cellulose to 5-HMF in an ionic liquid/organic solvent (ethyl butyrate) biphasic system was investigated. The optimum conditions were an ionic liquid:organic solvent ratio of 1:4, reaction temperature of 130 °C, and reaction time of 3 h, which resulted in yields of 5-HMF and reducing sugar of 40.95% and 41.7%, respectively. The ionic liquid was re-utilized. The re-utilization process of the biphasic system was also studied. The solvent [BMIM]Cl could be reused twice. The primary recovery rate of [BMIM]Cl was 75.6%, and the yield of 5-HMF was 32.6%. The second recovery rate of [BMIM]Cl was 46.8%, and the yield of 5-HMF was 17.6%.

Solid fuel for heating is an important product, and for sustainability reasons, it is important to replace nonrenewable fuels with renewable resources. This entails that the raw material base for pellet production has to increase. A broader spectrum of materials for pelleting involves variation in biomass substances. This variation, due to lack of knowledge, limits the possibilities to increase the pellet production using new raw materials. In this study, pellets were produced with a single pellet press from 16 different pure biomass substances representing cellulose, hemicellulose, other polysaccharides, protein, lignin, and extractives, and five different wood species, representing softwoods and hardwoods. All pellets were analyzed for the work required for compression and friction, maximum force needed to overcome the backpressure, pellet hardness, solid density, and moisture uptake. The results showed that the hardest pellets were produced from the group of celluloses, followed by rice xylan and larch arbinogalactan. The weakest pellets were from the group of mannans. Conclusions are that the flexible polysaccharides have a greater impact on the pelletizing process than previously known, and that the differences between xylan and glucomannan may explain the difference in the behavior of pelletizing softwoods and hardwoods.

Kraft lignin (KL) was valorized by introducing phenolic hydroxyl groups and adjusting the molecular weight by oxidative depolymerization. Hydrogen peroxide with copper sulfate as a catalyst was employed in this process. The depolymerized lignin (DL) was characterized with differential ultraviolet spectrum (UV), Fourier transform infrared (FT-IR) spectrometry, gel permeation chromatography (GPC), and heteronuclear single quantum correlation (HSQC) spectra. Both the molecular weight (Mw and Mn) and the polydispersity of the depolymerized lignin decreased compared with default kraft lignin. The content of phenolic hydroxyl groups increased from 1.55 to 2.66 mmol/g. The depolymerized lignin was used in the synthesis of lignin-phenol-formaldehyde (LPF) resin as a substitution of phenol. The physical properties including viscosity, bonding strength, and free formaldehyde content of the adhesive met the GB/T 14704-2006 standard with the substitution of 50% phenol with DL.

Activated carbons were synthesized by thermochemical treatment of palm kernel shells (AC-PKS) and modified with ethylenediaminetetraacetic acid (AC-EDTA). The developed products were characterized by the surface area, porosity, and pH of point zero charge and were used for removal of Pb(II) ions from aqueous solution. The AC-PKS exhibited higher BET surface area (1559.9 m²/g) than the AC-EDTA (1100.7 m²/g). The influence of solution pH, adsorbent dose, initial Pb(II) ion concentration, and temperature on the removal of Pb(II) ions were examined and optimized. The adsorption of Pb(II) on AC-PKS and AC-EDTA fitted the pseudo-second-order kinetics model and the Langmuir model isotherm, respectively. The optimum conditions for sorption of Pb(II) were at the initial Pb(II) concentration of 150 mg/L, dosage 0.35 g (AC-PKS) and 0.25 g (AC-EDTA), and pH 4. Thermodynamic studies showed that the adsorption process was spontaneous and endothermic. The AC-PKS and AC-EDTA both demonstrated high Q_max of 80.6 mg/g and 104 mg/g, respectively, for Pb(II) adsorption. The adsorption data also fitted the Thomas fixed-bed adsorption model.

Selected parameters and their effects were analyzed relative to the surface quality of thermally modified oak wood (Quercus cerris), which was evaluated using the mean arithmetic deviation of the roughness profile (Ra) during planar milling. Each measurement was taken at various parameters of the milling process, such as cutting speed, feed rate, tool geometry, and thermal treatment of the material. The measured results were compared with results measured on thermally untreated specimens (20 °C). The total amount of material removal was 1 mm. These characteristics were measured using a contact profilometer. Based on the results, thermal modification did not have a statistically significant effect on the roughness. The feed rate, rake angle, and cutting speed had the most significant effects on the monitored characteristic. The lowest average roughness values were found with a rake angle of 25°, feed rate of 4 m/min, and cutting speed of 40 m/s. Increasing the cutting speed led to a reduction in the average roughness, while increasing the feed rate had the opposite effect.

To overcome the numerous disadvantages of existing testing technology, a novel, fast, nondestructive, and quantitative technology for quality evaluation of Chinese eaglewood (CE) based on near-infrared (NIR) technology was proposed in this study. The extractives of CE were qualitatively analyzed to determine the types of volatile compounds using gas chromatography-mass spectroscopy and were quantitatively determined using high performance liquid chromatography (HPLC). Agarotetrol was quantitatively determined by the HPLC analysis. The content was found to range widely from 0.016 to 0.104 mg/g. A quantitative prediction model aimed at quality control was proposed based on the qualitative and quantitative results coupled with a partial least squares regression. The coefficient of correlation and residual predictive deviation of the prediction model were determined to be 0.9697 and 5.77, respectively. The practical tests showed an average error of 0.000327%, which indicated that the method was able to provide a novel, quick, and effective quality evaluation of CE.

A carbonized cassava dregs-supported ruthenium nanoparticles catalyst (Ru/CCD) was prepared by a simple impregnation-chemical reduction method. The synthesized Ru/CCD catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalytic performances of the Ru/CCD catalysts were evaluated in the conversion of D-glucose into D-sorbitol under hydrogen atmosphere. Moreover, the effects of various parameters on glucose hydrogenation and the recyclability of the catalysts were investigated in detail. The optimized D-sorbitol yield reached up to 98.6% at 120 °C for 1.5 h with D-glucose conversion of 99.7%. The Ru nanoparticles played an important role in the hydrogenation of D-glucose into D-sorbitol, and the Ru particle was widely dispersed all over the support surface. In addition, the Ru/CCD catalyst was stable during the reaction and was reused for up to five successive runs with a slight decrease in D-sorbitol yield.

The goal of this research was to examine factors affecting the feasibility of manufacturing particleboards at significantly lower density, while reducing the formaldehyde emissions. A further goal was to not significantly affect other important physical and mechanical properties of the boards, including swelling in thickness, surface absorption, bending strength, modulus of elasticity, internal bond, and surface soundness. By varying the raw material recipe (ratio between hardwood and softwood chips), it was found that increasing the amount of hardwood chips led to a significant decrease of the formaldehyde emissions, but also to a significant increase of the thickness swelling and surface absorption. The simple density reduction of particleboards was not a viable alternative because all properties were seriously affected. Therefore, the tests on particleboards with reduced density were repeated, but this time an isocyanate-based additive was added into the recipe at 0.25% and 0.4%. A noticeable improvement of all analyzed properties was achieved.