Volume 13 Issue 1

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.

This work reports on the preparation of pinewood residues/recycled high-density polyethylene (HDPE) composites to evaluate their performance under flexion, extraction of nails and screws, and moisture absorption (MA) to assess their potential to replace medium-density fiberboards (MDFs). The effect of filler particle size (PS) was evaluated, and scanning electron microscopy (SEM) was conducted to elucidate the state of the interphase. The effect of UV-light accelerated weathering (AW) on samples with and without a UV stabilizer (UVS) was assessed. A dynamic mechanical analysis (DMA) was also conducted. The composites had better flexural performance, MA, and screw extraction resistance than the MDFs. However, AW affected the composites, mostly affecting those without UVS. Scanning electron microscopy showed the appearance of cracks on the surfaces with less UVS. The DMA results suggested that the composites with the largest PS showed a better resistance to creep.

Mechanical properties of wood dowel welding were studied using untreated and copper chloride (CuCl2)-treated wood dowels. The effect of the welding time (3 s, 5 s, and 7 s) was also studied. The treated wood dowels with a welding time of 3 s had the best pullout resistance. Fibers covered with black molten material generated by the high friction temperature were found at the welding interfaces. For the untreated groups, the degree of crystallinity of the welding interfaces was higher than that of the wood dowel. For the treated groups, the degrees of crystallinity for the welding times of 5 s and 7 s were lower than that of the wood dowel. By extending the welding time, the degree of crystallinity decreased. A thermogravimetric (TG) analysis was used to detect changes in the wood components. The hydrolysis of cellulose and hemicellulose occurred during immersion. The analyses illustrated that pyrogenic decomposition of the wood components occurred during the wood dowel welding process. For the treated groups, the degree of pyrolysis was higher than that of the untreated groups for the same welding time. An increased welding time also promoted pyrolysis during the welding process.

To meet the current demand in China for Eucalyptus globulus and Acacia mangium mixed pulping, a study was conducted to collect the near infrared (NIR) spectra of 150 mixed samples of E. globulus and A. mangium in which the content of E. globulus was manually controlled. After the original spectra were pretreated by first derivative and standard normal variate (SNV), the least absolute shrinkage and selection operator (LASSO) algorithm and cross-validation were used to calculate the optimal adjustment parameters of 14.30, 19.16, 12.10, and 9.74, respectively. The optimal calibration models for the content of E. globulus, holocellulose, pentosan, and acid insoluble lignin were generated. An independent verification of the calibration models showed that the root mean square error of prediction (RMSEP) for these models was 1.59%, 0.54%, 0.66%, and 0.40%, respectively. The absolute deviation (AD) was -2.58% to 2.73%, -0.91% to 0.84%, -1.19% to 1.06%, and -0.61% to 0.64%, respectively. The prediction performance of the four models was sufficient for real-time analysis in the pulping production line. The LASSO algorithm was judged to be efficient for the prediction and analysis of mixed raw materials in pulping industry.

The impact of the full-cell impregnation of pine wood was investigated with respect to changes in electrical resistance and the accuracy of moisture content measurement. This study compared the resistance of impregnated and untreated pine timber harvested from the northern part of Poland (Pomeranian region). The wood was impregnated by the vacuum-pressure method. The preservative (TANALITH E 3475) and coloring (TANATONE 3950) agents were based on copper salts. The results showed a dependence of wood resistance as a function of the moisture content. Impregnated and not treated wood samples were used. This result reflects the greater conductivity of the impregnate solution (based on copper salt) than the water. This phenomenon became more distinctive as moisture content value was above the Fiber Saturation Point (FSP).

Paper is produced mainly from wood fibrous pulps, which has been increasingly replaced by pulps from fast growing plants due to limited wood resources. In this work, properties of cellulosic pulps produced by the sulfate method from four fast growing grasses, poplar cultivar ‘Hybrid 275’, and European larch, as well as pine and birch wood chips, were compared. In addition, the cellulosic pulp yield, dimensions of fibers contained in the pulps and mechanical and optical characteristics of paper sheets produced from the pulps were compared. The pulp yield of the poplar cultivar ‘Hybrid 275’ (51.6%) was almost 5% higher than birch pulp (47.0%). Moreover, all of the investigated tensile properties of paper made from ‘Hybrid 275’ pulp were higher than for paper produced from birch pulp. Fast growing grasses, despite lower pulp yield (34.0 to 47.1%), showed comparable tensile properties to birch. Therefore, these pulps are promising raw materials for papermaking.