Research Articles

The efficacy of particleboards manufactured with sodium fluoride against mold fungi and Hylotrupes bajulus (L.) larvae was tested. Laboratory-size particleboards were manufactured from untreated wood particles with inclusion of fine sodium fluoride (NaF) at the 1, 1.5, and 3% levels relative to total particle weight. Sodium fluoride was introduced as powder during the manufacturing process just before blending resin with wood particles. The laboratory mold test indicated that even the lowest level of retention of NaF with or without leaching significantly reduced mold growth on particleboard surfaces when compared to the untreated control specimens. The increased retention of NaF from 1% to 3% further suppressed mold growth towards lowest levels even on leached specimens. The laboratory Hylotrupes bajulus larvae tests revealed that the particleboard environment with or without NaF is not appropriate for larvacidial activity. While the tested biocide, NaF, tested positive against mold growth on particleboard surfaces, no effect was determined relative to larval deaths.

Wood, as a natural and sustainable source, has many fields of utilization. It is crucial for people to use wood in housing in ways that reflect their preferences and attitudes. The focus of this study is to measure consumers’ thoughts, knowledge, and awareness of wood materials. A survey was conducted about how consumers’ knowledge and conscious attitudes are reflected in their purchase and use of various wooden domestic items, including wood furniture and woodenware. Survey data were analyzed using descriptive statistics and one-way ANOVA. The results indicated that individuals believe that wood is a natural and organic (45.6%) material that people enjoy and become happy (43.7%) when using it. ‘Furniture’ (82.5%) is the most frequent way of utilizing wood for individuals at home. However, these people tend to use wood composite furniture, which offers more functionality and design options (71.8%), as natural wood is an expensive material (57.8%).

The chemical properties of willow were studied following liquid hot water pretreatment. Three different temperatures of liquid hot water pretreatment were used (160, 180, and 200 °C) for periods of 30, 60, 120, and 240 min. The contents of extractives, lignin, holocellulose, glucose, and xylose was determined. Compared with the original sample, the results indicated that lignin and extractives content increased after pretreatment. Further, the content of xylose decreased significantly with increasing pretreatment time for all three temperatures. The highest glucose content was obtained under the conditions of 180 °C for 240 min. In addition, a significant correlation was found between the content of xylose in the solid fraction and the severity factor of treatment. To determine the changes in cellulose crystallinity, the total crystallinity index (TCI) and the lateral order index (LOI) were calculated from the Fourier-transform infrared spectroscopy spectra of cellulose. An increase in both of these structural characteristics was observed at all experimental temperatures.

Carboxylated cellulose nanocrystals (CCN) were prepared from bamboo pulp by ammonium persulfate (APS) with an ultrasonication-assisted technique. The effects of ultrasonication time, APS concentration, and reaction temperature on the yield of CCN were investigated. The morphology, structure, crystallinity, and thermal properties of prepared samples were analyzed by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The CCN presented rod-like shapes with diameter ranging from 10 to 30 nm and length of 50 to 200 nm. FTIR showed that CCN still kept with the basic chemical structure of cellulose, and at the 1735 cm-1 appearing the peak of C=O. The XRD pattern indicated that CCN was characteristic of the cellulose I crystal form, and the crystallinity of CCN was 63%. TGA revealed that CCN had a lower thermal stability than bamboo pulp. This research explored a low-cost and eco-friendly way to prepare CCN.

Adsorbable organic halogen (AOX) produced during the bleaching process contains polychlorinated dibenzo-p-dioxins. To predict AOX in a timely and economical manner during pulp bleaching, a soft sensor model based on pulp quality indices was developed by analyzing the correlation between the AOX in the bleaching effluent and the whiteness, Kappa number, and intrinsic viscosity of the pulp. Variations of the main components during pulp bleaching were considered to determine their effects on wastewater AOX content. The results showed that the models can predict the AOX content of bleaching wastewater precisely and rapidly. The high relevant between pulp components and whiteness, Kappa number, and intrinsic viscosity allows the soft sensor model to predict AOX value without interference of components. The developed model has practical importance for monitoring AOX emissions and controlling pollution, which is essential for the global optimization of bleached pulp production cost, pulp quality, and environmental impact. Additionally, it adapts to the requirement of intelligent control of the bleaching process.

Carbon dots have good dispersion capability, strong visible fluorescence, low toxicity, and photo-induced accepting and donating abilities. Carbon dots were obtained from biomass bacterial cellulose (BC) via one-step hydrothermal carbonization. Effects of hydrothermal time and temperature on the microstructure, fluorescence, and excitation wavelength dependent photoluminescence (PL) behavior were explored for the prepared carbon dots. The results showed that the carbon dots obtained directly from the BC (C dots) had small particle sizes (2.0 to 3.0 nm) and green luminescence behavior. Conversely, the N-doped carbon dots (N-C dots) exhibited more uniform and smaller particle sizes (approximately 1.0 nm), strong blue luminescence, acceptable fluorescence lifetime, and good stability in a wide range of pH values (2.0 to 10.0). Thus, carbon dots could serve as a fluorescent material used in high performance optical cellular imaging and highly sensitive bacterial detection.

A green, effective, and feasible reaction for esterification of lignin with oleic acid in water at room temperature was investigated. A surfactant-combined system (p-toluenesulfonic acid/4-dodecylbenzenesulfonic acid) was designed to simultaneously solubilize kraft lignin and disperse the oleic acid, producing microreactors for esterification. Esterification using a higher 4-dodecylbenzenesulfonic acid dosage at room temperature was found to be a good option, and an increasing oleic acid dosage had no effect on improving the degree of esterification. Structural characterization analyses confirmed the successful esterification of lignin with oleic acid, indicating the effectiveness and feasibility of esterification of macromolecules in water. Due to the introduction of a long flexible aliphatic chain, the lignin ester showed a noticeable decrease in glass transition temperature, an obvious increase in contact angle, and exhibited excellent thermoplasticity, processability, and hydrophobicity. Additionally, lignin-ester nanoparticles were prepared through the micellization of p-toluenesulfonic acid. Therefore, the method of esterification using surfactant-combined microreactors in water is promising for high value-added utilization of lignin.

Hierarchical porous carbons were prepared from several common lignins, including sodium lignosulfonate (SLS), alkali lignin (AL), and calcium lignosulfonate (CLS) via one-step carbonization at 800 °C for 10 h without oxygen or any additional templating/activation agent for the decolorization of dyes from wastewater. The obtained carbons showed high porosity and microporous-mesoporous-macroporous hierarchical porous structures. The specific surface areas of SLS-C, AL-C, and CLS-C were 346 m2/g, 405 m2/g, and 512 m2/g, respectively. The total pore volumes of SLS-C, AL-C, and CLS-C were 0.12 cm3/g, 0.21 cm3/g, and 0.28 cm3/g, respectively. The obtained carbon materials displayed excellent adsorption-decolorization abilities for 5 dyes, including ethyl violet, malachite green, cationic brilliant red, acid blue 92, and direct red 23. The concentrations of these 5 dyes in wastewater were reduced by SLS-C from 20 mg/L to 0.12 mg/L, 0.20 mg/L, 0.32 mg/L, 0.78 mg/L, and 3.77 mg/L, respectively, over a 60 min treatment. AL-C reduced these concentrations from 20 mg/L to 0.02 mg/L, 0.01 mg/L, 0.04 mg/L, 0.71 mg/L, and 1.72 mg/L over the same time period. In addition, the concentrations of these respective dyes were reduced by CLS-C from 20 mg/L to 0.01 mg/L, 0.01 mg/L, 0.02 mg/L, 0.30 mg/L, and 0.20 mg/L.

Dimensional accuracy of machining translates into susceptibility to defects in assembly of furniture elements. In the initial drilling phase, the tip of the drill may slip due to the properties of the workpiece, which may result in inaccurate machining. Taking this into account, it was decided to investigate this phenomenon for drilling in the side of the plywood board. Samples for testing were made of 18 mm thick, 13 layer birch-alder plywood, covered with melamine film, glued with phenol-formaldehyde glue. With the use of an industrial dowel drilling machine, 30 holes in each of three examined layer were made. All holes were made parallel to the layers – on the side of the plywood board, and their axes were located in three adjacent layers: the birch veneer layer, the adhesive layer, and the alder veneer layer. Two types of geometric accuracy of holes were analyzed: the distance between the real center of the hole and the nominal position and also the inclination of the hole axis from the nominal axis. The holes made in the adhesive layer showed approximately twice larger deviations compared with the holes made in two adjacent layers of veneer. There was no significant relationship between the deviations of the angle of holes axis and the inaccuracies in the position of their centers. Main conclusion: When drilling in the side surface of the plywood board, less accurate holes are obtained if the hole axis is located in the adhesive layer, and there is more accuracy if the hole axis is located in the veneer layer.

The wood grade used for Chinese zither panels is primarily determined through an artificial experience method, and the number of related practitioners is decreasing annually. In this study, a method using an improved BP neural network is proposed to assess the wood grade for Chinese zither panels. Abnormal spectral samples were first removed based on the Mahalanobis distance method. Normalization and Savitzky Golay second derivatization were applied to the remaining data set. According to the spectral peak, the spectral data were divided into three bands, which were applied to the model proposed in this paper, and the most critical spectral region for judging the wood grade of Chinese zither panels was obtained. Through principal component analysis, the appropriate feature variables were selected and applied to the experimental model for an analysis to reduce the calculated amount in the experiment. When the number of principal components was 6, the classification accuracy of unknown samples was 96.7%. Compared with the PLS model, the proposed model is more robust and accurate and has fewer losses. The experimental results indicated that the proposed method effectively identifies the wood grade used in Chinese zither panels.