Research Articles

The aim of this research was to evaluate the production of cellulases from locally isolated bacteria, Thermobifida fusca, using thermal and chemical treated oil palm empty fruit bunch (OPEFB) as substrate in liquid-state fermentation (LSF). T. fusca was successfully isolated and was a dominant cellulase producer in OPEFB composting at the thermophilic stage. Analysis of the surface morphology of OPEFB samples using Scanning Electron Microscopy (SEM) showed that the most significant changes after the combination of thermal and chemical pretreatment was the removal of silica bodies, and this observation was supported by X-ray Diffraction analysis (XRD), Fourier Transform Infrared (FTIR), and Thermogravimetric analysis (TG) showing changes on the hemicelluloses, cellulose, and lignin structures throughout the pretreatment process. As a result of the pretreatment, higher cellulase production by T. fusca was obtained. The highest activity for CMCase, FPase, and β-glucosidase using optimally treated OPEFB were 0.24 U/mL, 0.34 U/mL, and 0.04 U/mL, respectively. Therefore, it can be suggested that the combination of chemical and thermal pretreatments enhances the degradation of OPEFB for subsequent use as fermentation substrate, contributing to a higher cellulases yield by T. fusca.

The objective of this work was to assess the physical and mechanical properties of standing Taiwan incense cedar (Calocedrus formosana) using nondestructive techniques (NDT). In addition, the relationship between characteristics of standing trees and wood properties was established. Results indicated that the velocity values and bending properties decreased as tree height increased. In addition, velocity values of specimens were greater than those of logs and standing trees. After regressive analysis, the correlation coefficients (r) were 0.79 for standing trees and logs and 0.70 for logs and specimens. Not only the velocities measured by ultrasonic wave (Vu), tap tone (Vf), and vibration (Vt) methods, but dynamic MOE also correlated well with the static bending properties of specimens. In addition, the values of dynamic and static MOE showed the following trend: DMOEu > DMOEf > DMOEt > MOE. For all specimens, the r values were found to be 0.92 for MOE and DMOEt, and 0.75 for MOR and DMOEt. Therefore, it was assumed that the nondestructive testing methods can provide basic information about standing trees and specimens for future management practices and utilization of Taiwan incense cedar.

Surveys of indigenous weeds in six provinces located in the low northern part of Thailand were undertaken to determine the potential of weed biomass for bio-energy and bio-ethanol. The results reveal that most of the weed samples had low moisture contents and high lower heating values (LHVs). The LHVs at the highest level, ranging from 17.7 to 18.9 Mg/kg, and at the second highest level, ranging from 16.4 to 17.6 Mg/kg, were obtained from 11 and 31 weed species, respectively. It was found that most of the collected weed samples contained high cellulose and low lignin contents. Additionally, an estimate of the theoretical ethanol yields based on the amount of cellulose and hemicellulose in each weed species indicated that a high ethanol yield resulted from weed biomasses with high cellulose and hemicellulose contents. Among the collected weed species, the highest level of ethanol yield, ranging from 478.9 to 548.5 L/ton (substrate), was achieved from 11 weed species. It was demonstrated that most of the collected weed species tested have the potential for thermal conversion and can be used as substrates for ethanol production.

Different hydrogen bond and crystalline cellulose structure models of eucalyptus fibers were studied by Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS 13C NMR). It was shown that when the beating time was increased from 5 to 15 min., the content of inter-molecular hydrogen bonds, O(6)H···O3′, increased by 11.2% as measured by FTIR. However, the content of the inter-molecular hydrogen bonds decreased quickly as the beating time was increased from 15 to 25 min. Meanwhile, the contents of the intra-molecular hydrogen bond, O(2)H···O(6) and O(3)H···O(5), changed from 8.25% to 8.18% and from 39.33% to 31.27%, respectively, when the beating time increased from 5 to 15 min. The content of the intra-molecular hydrogen bonds increased quickly with the further increase in the beating time. It was shown by XRD that there was a little difference in the average width of crystallite size in the (002) lattice plane when the beaten time was between 5 to 25 min. Non-linear fitting of the cellulose C4 region of the 13C CP/MAS NMR showed that the average lateral fibril aggregate dimensions and the content of different cellulose polymorphs changed during beating.

Two series of rosin quaternary ammonium salts (QAS) were synthesized using the same path. The structure of the target products was characterized by HPLC, MS, IR, and 1HNMR, and the bioactivity was determined by filter paper method using Trametes versicolor(white-rot fungus) and Gloeophyllum trabeum (brown-rot fungus), which are two kinds of general wood decay fungi in nature. The results showed that all compounds tested had a satisfactory anti-fungal effect at the molarity of 0.025 mmol/mL. Hereinto, acrylpimaric Gemini QAS had better bioactivity than dehydrogenated or tetrahydrogenated rosin QAS against Trametes versicolor. To this fungus, quaternary ammonium groups, which wraps up the membrane of microorganism and disrupts the balance in cell membrane, plays the leading role for its bioactivity. ToGloeophyllum trabeum, the inhibition activity of acrylpimaric QAS and dehydrogenated rosin QAS are almost at the same level and larger than tetrahydrogenated rosin QAS, so we conclude that both quaternary ammonium group and aromatic group play important roles. Compared with dodecyl dimethyl benzyl ammonium chloride (1227), which is a commercially available quaternary ammonium salt type fungicide, acrylpimaric acid quaternary ammonium salts have approximate bioactivity against Gloeophyllum trabeum. In conclusion, rosin derivatives with functional groups would do well in wood preservative applications.

Tannin/furanic rigid foam made from raw materials of natural origin could be used to replace polyurethane and phenolic foams in many future applications. In this study, diethyl ether, pentane, and a mixture of the two were used to prepare tannin/furanic foams having different microstructures. It was found that the bulk density of the foam could be significantly extended, up to 180 kg/m3. The cell size of the pentane foam was larger than that of diethyl ether foam with comparable density; however, both presented a sudden increase in cell size when the density decreased. The thermal conductivity and mechanical properties were determined for the two foam types at the same density but different cell size. The minimum thermal conductivity for diethyl ether and pentane foams were presented, along with a suggested method for lowering the thermal conductivity of such foam. Additionally, the results of mechanical tests indicate that cell size does not play a role in compressive strength.

Chemical modifications of Scots pine (Pinus sylvestris) wood flour were performed with vinyl acetate (VA) and acetic anhydride (AA) in the presence of potassium carbonate as a catalyst. Scots pine wood flour samples were successfully acetylated with VA (19 wt% gain) and AA (24 wt% gain). The effect of chemical modification of the Scots pine wood flour with AA and VA on the mechanical properties of wood high-density polyethylene composites (WPC) was determined. It was observed that acetylation of wood flour allowed a significant increase in both the mechanical properties and the thermal stability of the WPCs. It was concluded that acetylation of lignocellulosic fibers improves thermal stability, dispersion in the polymer matrix, and compatibility with the polymer matrix.

There is a large interest in bio-polymers as environment-friendly alternatives to synthetic additives in papermaking. In this work, the behavior of three chitosans with different molecular weights and cationic charges were investigated as flocculation additives in papermaking on two systems: calcium carbonate (GCC) and pulp/GCC suspension. Comparison was made with two traditional cationic polymers used in wet end chemistry (poly-diallyldimethyl-ammonium chloride (PDADMAC) and poly-ethylene imine (PEI)). Flocculation efficiency was evaluated by flocculation parameters (mean floc size and number of counts) and by floc behavior under shear conditions, using a focused beam reflectance measurement (FBRM) technique. Results indicated different behaviors between the three chitosans when they were used for the flocculation of GCC and pulp/GCC suspensions. Chitosans were found to be more efficient over PDADMAC and PEI for flocculating small particles of the GCC suspension, but less efficient for increasing floc sizes, regardless of their MW or CCD. Flocculation parameters for pulp/GCC suspensions suggested the flocculation behavior of chitosan was close to that of PEI, but chitosan had higher efficiency and affinity towards cellulose fibers.

Natural fibers such as kenaf have been studied extensively as a reinforcing phase and received major attention recently due to their renewability, biodegradability, and high strength comparable to other synthetic fibers. In this study, nano-crystalline cellulose (NCC) was produced from kenafcore wood using the acid hydrolysis method. Kenaf core was alkali treated with a 4 wt% of sodium hydroxide solution and subsequently bleached using sodium chlorite in acidic buffer. The resulting white, bleached kenaf core was hydrolyzed in 64 wt% sulfuric acid (H2SO4) to obtain NCC. The resulting NCC suspension was characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) analysis, and scanning transmission electron microscope (STEM). Hydrolysis with highly concentrated H2SO4 further increased the crystallinity of bleached kenaf core cellulose and reduced the dimension of cellulose to nano scale. FTIR results showed that with each subsequent treatment, hemicellulose and lignin were removed, while the chemical functionalities of cellulose remained after the acid hydrolysis treatment. XRD peaks shown by bleached kenaf core were characteristic of cellulose I, which was reaffirmed by the DSC results. The diameters of NCC obtained from kenaf core were found to be in the range of 8.5 to 25.5 nm with an average aspect ratio of 27.8.

The aim of this study was to evaluate the effect of CNC routing, using different parameters with the Taguchi experimental design, on the surface quality of various wooden (pine, spruce, and beech) edge-glued panels (EGP). The study evaluated five processing parameters: cutting direction, cutting depth, cutting width, feed rate, and spindle rotation speed, and their effects on surface roughness on pine, spruce, and beech EGP. Based on the results of statistical analysis of the burr surface roughness values, the mentioned parameters affected panels at varying levels. It was seen that the parameters were only responsible for ~34% (Rz) of the roughness on the surface of pine EGP, ~49% (Rz) of spruce EGP, and ~27% (Rq) of beech EGP. Statistically important parameters were as follows: cutting direction for pine, cutting depth (tip diameter) and feed rate for spruce, and cutting direction and feed rate for beech.