Research Articles

Effects of biochar on different soil types were studied in soil column experiments. The results showed that the biochar decreased filtrate heavy metals concentration by 89.0% to 95.7% (Cd) and 93.2% to 99.3% (Pb) compared with the control. The biochar application changed 2.3% to 9.84% of the exchangeable Cd fraction Pb to residual fractions, so the bioavailable Cd and Pb were reduced by 4.48% to 10.69% (Cd) and 11.74% to 16.42% (Pb) in surface soil (0 to 4 cm). Through increasing the soil ratio, the concentration of bioavailability of Cd and Pb was decreased 13.84% to 16.15% and 4.02% to 13.40% in 4 to 8 cm soil. With sandy soil, the application of biochar effectively reduced the down migration of heavy metals, and accomplished the conversion of 100.0% and 95% exchangeable Cd and Pb fractions into 13.1 to 43.9% residual Cd and 11.6 to 100.0% residual Pb. The SOM and pH also increased 1.2 to 2.3 g kg-1 and 0.01 to 0.31 with biochar application. The biochar effectively increased the SOM content, and stabilized heavy metals, then reduced the migration of Cd and Pb.

Reaction wood is characterized by having different anatomical and chemical features than normal wood. The different composition of cell walls, the higher quantitative proportion of thick-wall fiber cells, diameter, and the abundance of vessels have remarkable effects on reaction wood’s physical and mechanical properties. Reaction wood has fewer vascular cells. In addition, it has a smaller lumen diameter, which results in reduced permeability. Therefore, reaction wood is more difficult to dry at a certain moisture content. The differences in the drying times of the reaction wood and the normal wood were largest at a temperature of 60 °C and durations greater than 30 h, and the reaction wood dried more slowly. At a temperature of 120 °C, the differences in drying time were minimalized, and drying end times were almost identical. The expected negative effect of higher temperature on the morphology of reaction wood and opposition wood was not confirmed.

Excess lignocellulose fines in some fiber processing mills cause issues and hurt product quality. To use this type of biomaterial as a resource, surplus fines can be separated and dissolved with solvents for further transformation. Therefore, 1-butyl 3-methyl imidazolium chloride ionic liquid (IL) was used as a powerful green solvent for a rapid dissolution process. However, a low degree of polymerization (DP) of the cellulose in fines and the effects of lignin content and its structure on the process and film properties are controversial subjects. This study demonstrated that the three dimensional structure of lignin did not permit the raw bagasse fines (prior to pulping) to dissolve in the IL even after several hours. However, following decomposition of the lignin structure by pulping, the fiber fines were readily dissolved. Further, all the fabricated films from the fiber fines exhibited satisfactory strength properties, despite the fact that the cellulose had a low DP. The films from bleached fiber fines showed higher tensile strength than those containing lignin, although the cellulose chain was longer and had a higher DP for the latter. Lignin resulted in reduced transparency, and higher absorption of ultraviolet radiations, but it did not affect the surface roughness of the films.

To give cellulose fibers dual characteristics of warming and fluorescence, graphene oxide (GO) and fluorescent particles were simultaneously dispersed into the regenerated cellulose spinning solution through blending modification and post-reduction methods. After dry-jet wet spinning and reducing in hydrazine hydrate solution, the reduced graphene oxide (RGO)/regenerated composite fibers with different mass ratios of filler were completed. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence microscopy, and other methods were used to characterize the structure and morphology of fibers. Test results showed that the thermal stability and infrared emissivity increased gradually with the increase of GO. The crystallinity and strength of the composite fiber first increased and then decreased. This type of fiber also had luminescent properties after addition of fluorescent agent. However, when too much fluorescent agent was added, the thermal stability, infrared emissivity, crystallinity, and other properties mentioned above were affected to some extent. According to the comprehensive analysis, when the amount of GO added was 1 wt% and fluorescent added was 3 wt%, respectively, the luminescence characteristic and far-infrared emissivity of the fibers were remarkably improved.

Pyrolysis experiments were conducted in a tubular furnace from room temperature to 600 °C at 5 °C /min, and kept for 15 min. The light tar was then derived from the liquid products of pyrolysis by n-hexane supersonic extraction. Gas chromatography–mass spectrometry was employed to analyze the light tars from cotton stalk (CS) pyrolysis, Shenmu coal (SM) pyrolysis, and co-pyrolysis of CS/SM. Microcrystalline cellulose (MCC) was selected as a model compound, and the light tar from co-pyrolysis tar of MCC/SM was investigated for comparison. The results indicated that CS improved the yields and quality of phenols and benzenes in co-pyrolysis tar and that MCC had excellent performance in the formation of mononuclear aromatics during the co-pyrolysis of MCC/SM. Based on the pyrolytic behavior of CS and SM, the mechanisms of aromatic formation were further determined. It was shown that the free radicals that cracked from CS accelerated the formation of aromatics. The alkyl and mononuclear aromatic radicals of CS pyrolysis combined with the radicals from the SM aromatic structure, which then converted to benzenes and phenols. Finally, the most favorable reaction routes of mononuclear aromatics formation were proposed.

Characteristics and performances of a blended jatropha bio-epoxy/epoxy as a matrix in carbon fiber reinforcement was studied. The amount of bio-epoxy was arranged from 0 wt%, 25 wt%, 30 wt%, 40 wt%, and 50 wt% of the total matrix. Several analyses were performed to characterize and observe their performance. Fourier transform infrared spectroscopy, thermal analysis, physical characteristics, flammability, and soil burial were conducted, as well as mechanical tests. The results showed that introducing bio-epoxy in the matrix changed characteristics and increased or decreased their performance. Blending more than 25 wt% of bio-epoxy led to improved thermal stability between 280 °C to 350 °C and better biodegradability. However, tensile and flexural strength as well as modulus of elasticity decreased once the proportion of bio-epoxy was greater than 25 wt%. The paper proposed an optimal amount of jatropha bio-epoxy so that an alternative biocomposite application could be introduced to minimize carbon footprint in the environment.

Blended species plywood blocks comprising of 24 different veneer configurations of naturally durable white cypress pine and non-durable hoop pine were exposed to the subterranean termite Coptotermes acinaciformis in a field trial in Australia. Three thicknesses of cypress (1.8, 2.8, and 3.0 mm) and hoop pine (1.0, 1.5, and 3.0 mm) veneer were included. Blocks were assessed for termite damage using a visual damage rating and mass loss measurement. Blocks using all hoop pine veneers received substantial damage; however, blocks that had cypress face and back veneers had improved termite resistance, particularly for the 1.0-mm hoop pine core veneers. When cypress longbands were blended with hoop pine crossbands that created alternating layers, minimal damage was sustained in the hoop pine veneers; however, the damage increased with increasing hoop pine veneer thickness. All cypress veneers received essentially no termite damage, and cypress veneer thickness did not influence the severity of hoop pine veneer damage. The trial indicated that the plywood made with hoop pine core veneers, cypress pine face, and back veneers offered some termite resistance if the hoop pine veneer thickness was kept thin. Alternating cypress and hoop pine further improved the termite resistance.

To explore the properties of wood-plastic composites (WPCs) used in maritime climates, four different plant fibers (bamboo, rice straw, wheat straw, reed straw), and polyvinyl chloride (PVC) were used to prepare WPCs through extrusion. The composites were subjected to either seawater immersion + xenon lamp aging or deionized water spray + xenon lamp aging. The mechanical properties (tensile strength, flexural strength, impact strength), color change, and water absorption performance were analyzed. The plant fibers were analyzed by X-ray diffraction and Fourier transform infrared spectroscopy (FTIR), and the microstructures of the surfaces were observed by scanning electron microscopy (SEM). The reed fiber had the highest crystallinity; reed/PVC composites had good interface with the plastic matrix, less internal defects, and the best comprehensive performance, with a tensile strength, bending strength, and impact strength of 25.4 MPa, 34.4 MPa, and 4.30 KJ·m-2, respectively. The simulated seawater immersion + xenon lamp aging reduced the performance of wood-plastic composites, destroyed the quality of the combination of plant fibers and plastic matrix, and created internal defects. The comprehensive mechanical properties of reed/PVC composites were the best. The properties of bamboo/PVC composites decreased the least, with a decrease of less than 41.2%.

Lignin-containing nanofibrillated cellulose (LNFC) were prepared from p-toluenesulfonic acid (p-TsOH) pretreated sugarcane bagasse (SCB) using either formic acid (FA) or hydrochloric acid (HCl) and high-pressure homogenization. The composition, morphology, dispersity, crystallinity, particle size, thermal stability, and hydrophobicity of LNFC treated with FA (F- LNFC) and HCl (H- LNFC) were compared via electron microscopy, an X-ray diffractometer (XRD), a thermal gravimetric analyzer (TGA), a Fourier transform infrared spectroscope (FTIR), and water contact angle (WCA) analysis. The results of morphology and dispersity testing showed that LNFC with uniform dispersion were successfully prepared using a homogeneous pressure of 30 MPa and the F- LNFC particles were more stable in an aqueous solution. The crystallinity of the LNFC was well maintained after homogenization. The TGA, FTIR, and WCA data indicated that F-LNFC had better thermal stability and were more hydrophobic than H-LNFC because FA could esterify cellulose. Improved dispersity and thermal stability and increased crystallinity and hydrophobicity of cellulose nanofibrils would enhance the performance of nanocomposite materials.

Regenerated cellulose film (RCF) has potential as a conductive substrate due to features such as its degradability, transparency, and flexibility. Indium doped tin oxide (ITO) is a conventional conductive material, but its rigidity restricts the formation of flexible conductive film. In this study, silver nanowires (AgNWs) were introduced between the RCF and the ITO conductive framework. Additionally, the fabrication of flexible, conductive, and transparent RCF was conducted. The AgNWs-ITO based RCF demonstrated high conductivity (170 Ω per sq) and transparency (78%) by the addition of 50 μL of AgNWs. After bending the sample 50 times with a 5 mm curve radius, the as-prepared conductive RCF presented an electric resistance improvement of 19%, with a 485% increase for the control ITO-based RCF. This is a result of the AgNWs framework, which can lessen the destruction of the bending treatment on the conductive layer and can also desirably connect the ITO conductive sections. The novel approach can expedite the versatile applications of flexibly conductive RCF on printable, portable, and wearable electronic devices.