Research Articles

This paper deals with the moisture diffusion coefficient of Dahurian Larch (Larix gmelinii Rupr.) by use of the Finite Difference Method (FDM). To obtain moisture distributions the dimensional boards of Dahurian Larch were dried, from which test samples were cut and sliced evenly into 9 pieces in different drying periods, so that moisture distributions at different locations and times across the thickness of Dahurian Larch were obtained with a weighing method. With these experimental data, FDM was used to solve Fick’s one-dimensional unsteady-state diffusion equation, and the moisture diffusion coefficient across the thickness at specified time was obtained. Results indicated that the moisture diffusion coefficient decreased from the surface to the center of the Dahurian Larch wood, and it decreased with decreasing moisture content at constant wood temperature; as the wood temperature increased, the moisture diffusion coefficient increased, and the effect of the wood temperature on the moisture diffusion coefficient was more significant than that of moisture content. Moisture diffusion coefficients were different for the two experiments due to differing diffusivity of the specimens.

This study investigated the influence of heat treatment on the chemical composition and energy properties of maritime pine (Pinus pinaster) and pedunculate oak (Quercus robur). Samples were treated in a new experimental device at 220, 250, or 280 °C for 1 or 5 hours. Chemical and energy analyses were performed using standard methods. Our results clearly demonstrated an increased degradation of the material due to the combined effects of temperature and treatment duration. This mass loss was basically due to degradation of acid-soluble materials. The energy analysis showed that the fixed carbon content and higher heating value increased, for both species, whereas the volatile matter content decreased with increased extent of treatment (cumulated effects of temperature and time). In the range of temperature and duration studied here, the dimensionless energy properties for both species obeyed the same functions of overall mass loss. The relationships obtained allow quantification of the increase in wood energy concentration due to torrefaction. Mass loss is an excellent indicator of treatment extent. Analytical expressions allowing the prediction of energy and chemical properties as a function of overall mass loss, within the range of treatment extents studied here, are provided.

Despite significant progress having been achieved in recent years to improve wood’s durability, additional developments are still necessary to increase its color stability. ZnO and CeO2 nanoparticles were compared to UV absorbers (Tinuvin 477 DW, 292 and 5151) commonly used to stabilize the wood products color. Nanoparticles, with concentrations in the range 1 to 2 wt%, and UV absorbers, using concentrations advised by the manufacturer, were dispersed in a waterborne UV curable polyurethane/polyacrylate resin. Dispersions were carried out with a high speed mixer at 2,500 RPM with micro glass beads or not, depending on the form of the nanoparticles. Nanocomposite coatings were aged with a weather-o-meter (CI 3000+ – Atlas) according ASTM G155. Color variations were measured with a colorimeter (BYK Gardner – Color Guide 45/0) working with the CIE L*a*b* system. The aim of the present study was to assess the effects of inorganic UV absorbers on the stabilization of color under indoor conditions. Results showed that nanoparticles (ZnO, CeO2) absorbed UV light frequencies in a manner similar to common organic molecules. Their efficiency was better at medium durations of light exposure, for which they could achieve the action of organic absorbers. Finally, the simultaneous use of both absorbers seems to create a protective synergy when degradation is due to UV energy alone.

Cellulose is the Earth’s most abundant biopolymer. Exploiting its environmentally friendly attributes such as biodegradability, renewability, and high specific strength properties are limited by our inability to isolate them from the secondary cell wall in an economical manner. Intermolecular and intramolecular hydrogen bonding between the cellulose chains is the major force one needs to overcome in order to isolate the cellulose chain in its microfibrillar form. This paper describes how a hydrogen bond-specific enzyme disrupts the crystallinity of the cellulose, bringing about internal defibrillation within the cell wall. Bleached kraft softwood pulp was treated with a fungus (OS1) isolated from elm tree infected with Dutch elm disease. FT-IR spectral analysis indicated a significant reduction in the density of intermolecular and intramolecular hydrogen bonding within the fiber. X-ray spectrometry indicated a reduction in the crystallinity. The isolated nano-cellulose fibers also exhibited better mechanical strength compared to those isolated through conventional methods. The structural disorder created in the crystalline region in the plant cell wall by hydrogen bond-specific enzymes is a key step forward in the isolation of cellulose at its microfibrillar level.

ing recently in the pulp and paper industry. However, there is still a lack of data on the application of Mg(OH)2 in peroxide bleaching of non-wood fibres. In this work, our purpose was to study the effect of Mg(OH)2 on peroxide bleaching of wheat straw soda-AQ pulp. The results showed that Mg(OH)2 significantly improved peroxide bleaching efficiency (expressed as the ratio between the brightness gain and the H2O2 consumption) and selectivity (expressed as the ratio between the brightness gain and the viscosity losses) of wheat straw soda-AQ pulp. The brightness, viscosity, and yield of bleached pulp can be significantly enhanced by increasing the replacement ratio of Mg(OH)2 However, at 100% replacement of NaOH with Mg(OH)2, the brightness of bleached pulp was much lower than that of the bleached pulp with NaOH as the sole alkaline source. to 73% of the NaOH was replaced with Mg(OH)2, the COD of the bleaching filtrate was 11 to 38% lower than that of the NaOH as the sole alkaline source. The lower solubility and alkalinity of , as well as the reduction of Cu ion content in bleached pulp were proposed as accounting for the favorable effect of Mg(OH)2 on peroxide bleaching of wheat straw soda-AQ pulp.

The modified bleaching sequence OPAPPO from short-sequence bleaching OAP and OQP was studied in an effort to achieve higher quality straw pulp (with brightness 84.5% and acceptable viscosity 669 mL/g), which will be appropriate for more situations than straw pulp as presently produced. Though the OP and PO stages are recognized as the key processes used to increase the pulp’s brightness, addition of hydrogen peroxide in acid pretreatment with polyoxometalate (POM) as catalyst (AP stage) was mainly considered in this work. Phosphomolybdic acid was applied to improve straw pulp’s brightness, which was 4.8% ISO higher than the pulp treated without POM. The optimum conditions of the AP stage were: initial pH value 3, temperature 90 °C, H2O2 1.5%, and phosphomolybdic acid 1.0%. Comparison of the sequences OPQPO, OPAPO, and OPAPPO showed that the brightness of pulp bleached by OPAPPO was 2% and 4.7% higher than the same pulp subjected to OPAPO and OPQPO sequences, respectively. Four lignin samples (LOP, LOPA, LOPAP, LOPAPPO) were characterized by 31P NMR spectroscopy. The spectroscopic investigation showed that in LOPA and LOPAP, aliphatic hydroxyls, p-coumaryl units, and guaiacyl phenol moieties were degraded when compared with that in LOP. In LOPAPPO, all these aliphatic hydroxyls and guaiacyl phenols had been destroyed and carboxylic acid functionalities increased.

Lignin can be used as a cheap natural raw material to prepare organic aerogels based upon gelation and supercritical drying in ethanol. The aerogels were prepared from a mixture of the raw materials with lignin (L), resorcinol (R), and formaldehyde (F), followed by a reaction catalyzed by NaOH(C). The effect of the preparation conditions, such as the LRF concentration, the mass ratio of LR to NaOH (LR/C), the mole ratio of LR to F (LR/F), and the gelation temperature, on the gelation ability and the bulk density were studied. The results showed that the density of LRF aerogels increased with increasing reactant concentration and catalyst content. The microstructure of the porous carbon aerogels was investigated by SEM and TEM. The specific surface area and pore size distribution of LRF and RF aerogels were studied by nitrogen adsorption-desorption analysis. The pore width of LRF aerogels ranged from 1 nm to 100 nm. Most of the pores were about 50 nm wide, as is typical for mesoporous materials.

This paper reports the production of ligninase enzymes by a new strain of Trametes versicolor IBL-04 producing a novel pattern of ligninolytic enzymes with highest MnP activities followed by LiP and laccase. In previous studies Trametes versicolor has been reported to produce higher activities of MnP, followed by laccase and LiP. Lignocellulosic substrates including wheat straw, rice straw, banana stalks, corncobs, corn stover, and sugarcane bagasse were used in solid state fermentation (SSF) for the production of ligninases including peroxidase (LiP), manganese peroxidase (MnP), and laccase by Trametes versicolor IBL-04. Maximum production of MnP (998 U/mL), LiP (620 U/mL), and Laccase (49.7 U/mL) was observed after 5 days in the SSF medium containing 5g rice straw (60% w/w moisture) in still culture SSF. Moisture, pH, temperature, inoculums size, additional carbon and nitrogen sources, and surfactants had a significant influence on ligninase synthesis by the fungus. Production of ligninases was substantially enhanced by optimizing SSF production process. Maximum MnP (1775 U/mL), LiP (1663 U/mL), and laccase (99 U/mL) were produced when rice straw (5g) at 66.6 % moisture (w/w) receiving 5ml inoculum was incubated at pH 4.0 and 30oC in the presence of maltose (1% w/w) as carbon source, urea (0.2% w/w) as nitrogen source and 1mM Tween-80 (0.3 ml) as surfactant.

This study presents the utilization of oil palm ash (OPA), a siliceous material from the fiber of oil palm biomass, as a nanofiller for the development of polymer nanocomposites. Polypropylene-based polymer nano-composites reinforced with OPA along with a compatibilizer were prepared by a melt-mixing technique, using a double screw extruder. Variations in the mechanical, morphological, and thermal properties with the filler and compatibilizer loading were studied. The best dispersion occurred in the polymer nano-composites for which the interactions between the polymer matrix and nanosized OPA appeared to be the highest. The particle size and the dispersion of the oil palm ash within the matrix were determined by transmission electron microscopy. The as-synthesized composite materials were typically characterized by tensile and impact test methods. The morphology of the composite materials was studied by scanning electron microscopy. The thermal properties determined by thermogravimetric analysis (TGA) showed enhanced thermal stability of a series of composite materials. Also, melting studies were carried out by differential scanning calorimetry.

The influence of the variables soda (0.5-3.0%), hydrogen peroxide (1.0-6.0%) and time (1-5 h) in the bleaching of soda pulp of empty fruit bunches (EFB) from oil-palm, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models reproduced the results of brightness, kappa number, and viscosity of the pulps with errors less than 10%. By the simulation of the bleaching of pulp, using the polynomial and neural fuzzy models, it was possible to find optimal values of operating variables, so that the properties of bleached pulps differed only slightly from their best values and yet it was possible to save chemical reagents, energy, and plant size, operating with lower values of operating variables. Thus, operating with 1.13% soda concentration and 2.25% hydrogen peroxide concentration for 3 hours, a pulp with a brightness of 75.1% (8.1% below the maximum) and a viscosity of 740 mL/g (10.4% less than the maximum value), was obtained.