Volume 17 Issue 3

Cellulose nanocrystals (CNC) and succinic anhydride-modified CNC from bleached soda bagasse pulp under different parameters were used to remove Cd+2 and Pb+2 heavy metal ions from aqueous solution. The aim was to modify the chemical structure of cellulose nanocrystal using succinic anhydride and to investigate the effect of CNC and succinic anhydride-modified CNC on the adsorption capacity of heavy metal ions. The adsorption parameters included pH (3, 5, 6, and 8), contact time (30, 60, and 90 min), and initial metal ion concentration (40, 120, 200, and 280 ppm). It was found at all pHs that the adsorption capacity of the succinic anhydride-modified CNC adsorbent was much higher than that of the default CNC adsorbent, and this difference was greater at higher pHs. The results showed that the maximum metal ion adsorption was obtained at pH 6 for Pb+2 and Cd+2 ions. Both types of CNC had a higher adsorption capacity for lead ions than cadmium ions. To investigate the kinetic models of adsorption, the pseudo-first-order and pseudo-second-order kinetics model were used. Adsorption on unmodified adsorbent gave a better fit to the Langmuir model than the Freundlich model for both Pb+2 and Cd+2 metals. In addition, the adsorption mechanism was changed by modifying the adsorbent, and then it had better fit to the Freundlich adsorption model. Adsorption of cadmium and lead metals by adsorbents fit better to the pseudo-first-order kinetics model.

A high-efficiency composite adsorbent was synthesized by mixing cellulose and graphene oxide (GO) in the lithium chloride/N,N-dimethyl-acetamide system. The cellulose/GO composite (D-RCGO) was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, elemental analysis, and thermal gravimetric analysis. The influences of various parameters on the removal of Ce(III), such as the adsorbent dosage, temperature, initial Ce(III) concentration, contact time, and pH, were optimized using a range of batch adsorption experiments. Adsorption kinetics displayed adsorption behavior according to the Langmuir isotherm model and pseudo-second-order model. The X-ray photoelectron spectroscopy analysis showed that the two peaks of Ce-3d almost disappeared after the desorption in NaCl solution, which indicated that the adsorption belonged to the ion exchange adsorption mechanism. Furthermore, the theoretical maximum capacity of the adsorption of Ce(III) onto D-RCGO was 225.8 mg·g-1. This work suggested that the D-RCGO composite membranes could serve as an effective and eco-friendly adsorbent for rare earth pollutant removal in wastewater treatment.

The laccase activity of three cultivated Pleurotus strains was investigated using different lignocellulosic biomasses for solid-state fermentation. The lignocellulosic biomasses were Sophora japonica, Salix babylonica, Populus beijingensis, and Pinus tabuliformis, which were selected because of their laccase producing ability and low cost. The maximum laccase activities from P. ostreatus Han 1189, P. citrinopileatus Han 1192, and P. eryngii Han 1205 using Sophora japonica were 768.74 U/L ± 11.25 U/L, 144.77 U/L ± 9.70 U/L, and 200.42 U/L ± 6.85 U/L, respectively. The three species of Pleurotus showed consistency in having a preference of hardwood to secret laccase under solid-state fermentation when facing hardwood and softwood as substrates. Furthermore, the presence of Sophora japonica was beneficial to improving the laccase activity for three Pleurotus strains. The capacity of the laccase secretion of P. ostreatus Han 1189 was superior to the capacity of P. citrinopileatus Han 1192 and P. eryngii Han 1205. The discovery was helpful for obtaining new high-producing strains and suitable wood materials, as well as expanding these high-producing strains for industrial applications to obtain high laccase activity, high laccase yield, and low cost laccase.

The bending performance of wood is important for its application in furniture, and it is one of the criteria used to assess the suitability of a particular wood species for furniture. In this context, the steam-bending and surface roughness characteristics of four forest plantation wood species were evaluated. One batch of wood specimens were subjected to both surface roughness experiments using the stylus and toluene spread methods, while another batch of the wood specimens were subjected to steaming, clamped, and bent using a circular shape mold. The instantaneous spring-back was measured after 10 days, while the spring-back over time was measured from days 15 to 65. The surface roughness experiments showed that the Hevea brasiliensis had the lowest surface roughness, followed by the Eucalyptus pellita, Acacia mangium, and finally Revotropix paulownia. In terms of the bending performance, it was found that only the H. brasiliensis achieved the threshold 95% satisfactory level based on visual ranking. Furthermore, the wood species also recorded the lowest spring-back, both instantaneous and over-time, to register the best bending performance. On the other hand, R. paulownia had the worst bending performance, primarily due to its low density.

To improve the color and surface properties of blue-stained radiata pine, heat treatment was carried out at different temperatures and times. The color change, wettability, and dynamic moisture sorption of the wood were investigated. The results showed that, as the treatment temperature and duration time increased, the surface brightness of specimens gradually decreased, and the surface color became more reddish and blueish. In addition, the contact angle of distilled water at 0 s and 18 s gradually increased as the treatment temperature and time increased, which indicated a decrease in the surface wettability. The color of the blue-stained wood became more uniform with reduced surface wettability and hygroscopicity but increased sorption hysteresis after the treatment.

Stout camphor tree (Cinnamomum kanehirae) is an economically and socially valuable timber species that is conserved in Taiwan Province, China. In this study, Illumina sequencing technology was used to identify genes in C. kanehirae and analyze their levels under drought and low temperature stresses. The obtained reads generated 27,885 single genes, including 8,136 that were differential. Based on the results of Kyoto Encyclopedia of Genes and Genomes enrichment, the primary metabolic pathways in response to drought and low temperature stress included sucrose and starch metabolism, photosynthesis, glycolysis and sugar metabolism synthesis, phenylpropanoid biosynthesis, plant-pathogen interaction, and flavonoid biosynthesis, as well as the identification of transcription factors (TFs) with different patterns of expression. Finally, the RNA-Seq data were validated using real-time fluorescence quantitative analysis to identify TFs with different patterns of expression. These data provide a valuable resource for further research on the molecular mechanisms of drought and low temperature stress in C. kanehirae and contribute to the exploration of drought and cold resistance genes.

Polycaprolactone (PCL) is an eco-friendly and biodegradable synthetic polyester encouraged by various government authorities. These biodegradable bioplastics and lignocellulose composites have attracted people’s attention. Usually, neat PCL has poor interfacial compatibility with potential reinforcing particles and poor mechanical properties, which limit its application. The drawbacks can be effectively solved with maleic anhydride (MA) and microcrystalline cellulose (MCC). In this study, PCL composites were prepared by the one-pot synthesis method. The roughness of the PCL-MA/MCC film was reduced 66.7%, the contact angle (CA) reached a maximum of 87.5°, and its tensile strength was effectively improved by 77.8%. The thermodynamic properties of PCL-MA were similar to PCL. In contrast to PCL, the thermodynamic properties of PCL-MA were minimally affected, and the main chain structure of PCL was not broken despite the formation of new chemical groups. Its interfacial compatibility and mechanical properties were effectively improved.

A binderless board was produced from mechanically dissociated compost straw via suction filtration. The binderless board was applied to replace the topsoil that is currently used predominantly as the substrate for rice seedlings in China. The binderless board showed the highest tensile strength when the rice straw had been composted for 20 days. The bulk density, aeration, and total porosity of the binderless board showed an increasing trend with composting time, due to the increased decomposition of rice straw. The examination of the growth parameters and root morphology of the rice seedlings showed that electrical conductivity (EC), pH, and nutrient content of the binderless board made from rice straw composted for 10 days were conducive to the growth of seedlings. Polyphenols inhibited rice seedling height and shoot weight and promoted the rice seedling stem diameter and root weight. Considering the quality loss, growth index, and the strength of the binderless board, 10 days of composting is the optimal condition. These results indicate that binderless board can replace top soil and peat when used as the substrate for rice seedling.

Tectona grandis wood presents decent dimensional stability as well as highly suitable physical and mechanical properties. These characteristics have encouraged the intense usage of this species, which also includes the reuse of wood processing waste for panel production. Using teak wood waste, this study aims to manufacture and evaluate heat-pressed particleboards at 5 MPa and 100 °C, by being glued with castor oil-based polyurethane resin at proportions of 10% for the homogeneous boards and 12% for the heterogeneous solutions. Single-layer (homogeneous) boards were compared with three-layer particleboard specimens (heterogeneous) having the finer particles in the outer layers. The basic density, moisture content, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile, water absorption, and thickness swelling after 24 h were evaluated to support this comparative study. All the manufactured particleboards met the standardized requirements of performance, thus being very feasible for usage as non-structural boards. When the two different compositions were analyzed, a considerably better performance of the three-layered particleboards was identified when compared to the homogeneous panels.

For many product and applications, the penetration of preservatives or modification substances into wood species should be deep and homogeneous. Caucasian spruce and European larch are resistant to impregnation. This study compared how different incising pre-processes increased the retention of impregnation materials and the depth of their penetration into the structures of these refractory wood species. Mechanical, biological, and laser incising pretreatments were applied to increase the permeability of sapwood samples before the impregnation. To compare the uptake of the wood preservatives transverse and longitudinal to the axial tracheids in the samples, the cross-sections of some of the samples that had been subjected to different incising pretreatments were covered with a polyurethane-based paint. All wood samples were impregnated using a vacuum method with Celcure C4 new generation preservatives. The study compared the possible effects of these different incising pretreatments on the uptake of preservatives into the tracheids in the spruce and larch woods in both longitudinal and transverse directions. The results showed that the copper (Cu) uptake levels increased in these refractory wood species, especially in the transverse direction, after the different incising pretreatments. Moreover, the results showed it is very important to choose the most suitable pretreatment method for the refractory tree species before impregnation.