Volume 11 Issue 1

Dielectric barrier discharge (DBD) plasma at atmospheric pressure in air was applied to a poplar veneer surface. Effects of plasma processing rate on surface morphology, chemical property, and surface wettability of the poplar veneer were investigated. The adhesion strength of urea formaldehyde (UF) glued plywood manufactured from the modified veneer was also studied. Atomic force microscopy (AFM), electron spin-resonance spectroscopy (ESR), X-ray photoelectron spectroscopy (XPS), contact angle tests, and shear strength tests were carried out. AFM indicated that the surface roughness increased after plasma treatment and was the maximum at a processing rate of 14 m/min. Both ESR and XPS tests showed more oxygen accumulation on the wood surface, forming various oxygen-containing chemical groups. Contact angle tests showed better wetting at a decreased plasma processing rate. Consequently, the adhesion strength of plywood increased after plasma treatment and showed higher strength at lower processing rates.

A pot crop experiment was conducted to study the effect of biochar on Cu mobility in a soil-plant system. Pigeon pea biochar was prepared by slow pyrolysis at 300 °C. The experiment had three levels of Cu (0, 250, and 500 mg Cu kg-1 soil) and three levels of biochar (0, 2.5, and 5 g kg-1 soil), using spinach as the test crop. The dry matter yield of edible spinach leaf decreased by 16.7% and 27.9% at 250 and 500 mg Cu kg-1 soil concentration, respectively. The soil organic carbon (SOC) increased by 27.08% and 45.83% at 2.5 and 5 g kg-1 soil application of biochar, respectively. Cu mobility in soil was significantly reduced as a result of biochar application, as evident from the reduction in DTPA extractable Cu in soil, the transfer coefficient value (soil to plant), and the Cu concentration in the leaf and root. The increases in SOC and pH in the biochar amended soil affect copper dynamics because they control adsorption and precipitation on solid phase. Cu has higher affinity towards SOC and makes stable complexes, thereby decreasing the Cu mobility in soil. Adsorption and precipitation of heavy metals to solid phases and also increasing the negatively charged functional group due to increase in soil pH resulted in reduction of Cu mobility in soil.

Activated carbon fibers (ACFs) were prepared by steam activation of windmill palm (WP) (Trachycarpus fortunei) fibers in a nitrogen atmosphere at various temperatures in the 600 to 850 °C range, and their characteristics were investigated. The effects of temperature, in terms of porous texture and surface chemistry, were identified through the use of scanning electron microscopy (SEM), nitrogen adsorption-desorption, mercury intrusion porosimetry (MIP), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The results showed that the ACFs prepared at relatively high temperatures presented more cracking, collapsed surfaces, and lower yields because of the violent reaction that occurred during the activation process. With increasing temperature, more micropores were generated, and then the number eventually declined because of the conversion of partial micropores into mesopores. The ACFs with the highest special surface area, 1320 m2/g, and total pore volume, 1.416 cm3/g, were obtained at the activation temperature of 850 °C. In addition, graphitic carbon, the main compound on the surface of ACFs, decreased. Conversely, the amount of functional groups containing C-O (except for C-OH) slightly increased with increasing activation temperatures. It was also found that the mesopore volume and methylene blue adsorption of ACFs were highly increased as the temperature increased from 600 to 850 °C. Accordingly, WP fibers are a promising precursor for ACF production.

This study investigated the mechanical behavior and the variation of Dendrocalamus farinosus single fibres, which were isolated from fibre bundles using a chemical method. A micro-tester was applied to determine the influence of the age of the bamboo sampled, as well as the longitudinal and radial positions, on three indicators featuring tensile properties at the fibre level. The results indicated that the single fibres had a brittle failure mode, resulting in average tensile strength and tensile modulus (MOE) values of 1.06 and 26.93 GPa, respectively. The differing ages and positions across the whole culm appeared to be minor in relation to their tensile properties, which reached a near-optimal state at 2 years old and remained fairly constant. This work could provide basic-data for further research on bamboo properties and increase attention to a potential supplementary material to moso bamboo in industrial utilization.

Fast-growing poplar wood was modified with low molecular weight urea-formaldehyde resin (UF) at 41.5% concentration or phenol-formaldehyde (PF) at concentrations of 15, 25, and 40%. The physical and mechanical properties were measured, and creep behavior tests were carried out under ambient indoor conditions. The specimens were subjected to 30 and 50% of their maximum bending load. The density, modulus of elasticity, and modulus of rupture of UF-wood increased by 37.16, 45.86, and 28.36%, respectively, and the corresponding increases in 15% PF-specimen were 39.41, 31.80, and 27.74%, respectively. The wood modified with resins exhibited less creep deflection. The relative creep deflections of modified wood were about 0.22, 0.53, 1.22, and 0.32 times those of the untreated specimen at 30% of stress level after 15% PF, 25% PF, 40% PF, and UF were added, respectively. At the lower loading level, the relative creep deflection of the 15% PF specimen was 63.94% that of the 41.5% UF-specimen. Specimens treated with UF at 30 and 50% loading were broken within 120 d and 80 d respectively, whereas the untreated specimen was broken within one month at 50% loading.

Different solvent fractions (Fs) of water:methanol (1:1 v/v) of heartwood, bark, and leaf extracts of Robinia pseudoacacia were evaluated for their antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method; the antifungal activity against the mycelial growth of Trametes versicolor fungus was also determined. The most active fractions were analyzed for their chemical composition using gas chromatography–mass spectrometry (GC/MS). At higher concentrations (0.016 mg/mL), the values of antioxidant activity were 92.3%, 92.5%, 50.6%, 93.4%, and 96.6%, for heartwood F7 (ethyl acetate fraction), bark F7 (ethyl acetate fraction), leaves F9 (methanol fraction), BHT, and vitamin C, respectively. Among the fractions and concentrations of extracts from heartwood, F7 at 12.5 ppm led to the lowest growth of T. versicolor (22.00 mm); F7 of the bark extract showed good antifungal activity, with lower mycelia growth values reached 11.33, 11.33, and 13.00 mm at concentrations of 12.5, 25, and 50 ppm, respectively. For leaf extracts, F9 showed good antifungal activity at all concentrations, where the values of mycelial growth were 26.00, 25.33, and 28.33 mm at concentrations of 12.5, 25, and 50 ppm, respectively. These results indicated that the fractions of R. pseudoacacia can be a valuable and economic resource for use in antioxidant activity or as an antifungal activity against the growth of T. versicolor.

This paper explores the potential of wood for improving environmental quality in interior spaces. In northern climate cities where overcast skies predominate, interior spaces may appear gloomy or dull, since natural light is white and uniform. Nevertheless it is observed that wooden surfaces tend to create warmer and brighter spaces under overcast sky conditions. The objectives of this research were twofold. The first was evaluating the quality of wooden spaces under two sky conditions in terms of color, brightness and contrast. The second objective was to investigate daylight quantity of wooden spaces under diffuse and clear sky conditions. The method involved on site-surveys using Photolux, a calibrated photoluminance meter. Data consist of calibrated digital images that were processed to analyze the quality of spaces based on brightness, contrast, and color. The Kruger Building, with its internal wooden architectural structure and decorative indoor panels, was chosen as a site study for this research. Conclusions suggest that knowing the effect of different sky conditions on wooden spaces can help architects and other professionals in designing more comfortable and efficient ambiances. More particularly, this research addresses issues related to the quantitative effects of wood on daylighting distribution, visual comfort and luminance diversity.

Ink removal from recovered paper is a very important process in paper and board recycling. The current deinking processes have made obvious contributions to the use of raw materials for the paper and board industries. In contrast to the flotation deinking process, in which small air bubbles are used to remove ink from the pulp, the novel and more energy-efficient method of adsorption deinking technique depends on the attachment and adsorption of ink particles on small polymer beads. The energy savings of adsorption deinking results from the fact that the process is efficient at greater stock consistencies, thus providing water conservation and savings. The present study was carried out to improve the adsorption deinking method by identifying the optimum balance between the deinking chemistry and the polymer beads. Different types of deinking solutions and polymer beads were used for this study with newsprints and mixture of newsprints and magazines. It was found that EGA 3000 solution and polyethylene terephthalate beads worked well with newspaper pulp.

Batch experiments for the hydrolysis of xylan and pure cellulose (Avicel) hydrolysis and the decomposition of xylose and glucose were performed at varying sulfuric acid concentrations in the range of 10 to 50 wt.% and varying temperatures in the range of 80 to 100 °C. Increasing the temperature and acid concentration hastened the hydrolysis and the sugar decomposition rates. The hydrolysis rate of Avicel was much slower than that of xylan because of its crystallinity. The kinetic parameters for the concentrated acid hydrolysis reaction were estimated for both glucose and xylose reaction paths. The effect of initial cellulose crystallinity on the acid hydrolysis rate was also investigated, such that the cellulose was treated with various concentrations of phosphoric acid. A dramatic reduction in the cellulose crystalline index was observed when the phosphoric acid concentration was in a narrow range around 80 wt.%. It was found that the hydrolysis rate significantly increased with the decrease in initial cellulose crystalline index.

A simple and efficient method for the purification of oligomeric proanthocyanidins (LOPC) from degreased Larix gmelinii bark was developed. The purity of LOPC was increased from 51.7% to 92.2%, and the cumulative recovery rate was 97.0%. The reversed phase high performance liquid chromatography-mass spectrum (RHPLC-MS) analysis indicated that the percentage contents of catechin (CA), epicatechin (EC), and procyanidin B1 (PB1) in purified LOPC (P-LOPC) were 5.05%, 2.02%, and 0.71%, respectively. The percentage contents of catechin and procyanidin B1 were noticeably higher than those obtained from grape seed extract (2.77% and 0.61%). The average degree of polymerization of P-LOPC was found to be 2.66. The matrix-assisted laser desorption ionization-time of flight/mass spectrum (MALDI-TOF/MS) analysis demonstrated that the dimer was the major component of purified LOPC and the distribution range was from dimer (m/z 713) to decamer (m/z 3016.6). The IC50 values of P-LOPC against DPPH• (1,1-diphenyl-2-picryl-hydrazyl), OH• (hydroxy radical), and ABTS+ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt) were 76.4±3.82, 7.92±0.40, and 2.4±0.12. Purified LOPC exhibited more excellent physiological activity than VC (vitamin C), TBHQ (tert-butyl hydroquinone), and pine bark extract.