NC State
  • Researchpp 592-602Kaymakci, A., Ayrilmis, N., and Gulec, T. (2013). "Surface properties and hardness of polypropylene composites filled with sunflower stalk flour," BioRes. 8(1), 592-602.AbstractArticlePDF

    The effects of agricultural flour content on surface roughness, wettability, and surface hardness of injection molded polypropylene (PP) composites was investigated. Four content levels of the waste sunflower stalk flour (WSF) were mixed with the PP with and without maleic anhydride grafted PP (MAPP) as a coupling agent. Contact angle measurements were performed using a goniometer connected with a digital camera. Three roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax), were used to evaluate surface roughness. The surface roughness increased with increasing WSF content while their wettability decreased. The unfilled (neat) PP composites had the lowest surface roughness, while the roughest surface was found for the PP composites filled with 60 wt% WSF. The surface smoothness of the composites was noticeably increased by addition of the compatibilizer MAPP while the wettability was decreased. The scratch hardness of the PP composites increased significantly with increasing WSF. The incorporation of the coupling agent increased the scratch hardness of the specimens. The Brinell hardness increased with increasing filler loading. At similar filler loading the composites with MAPP had lower Brinell hardness value than those without MAPP.

  • Researchpp 603-611Hu, C., Jiang, G., Zhou, J., Xiao, M., and Yi, Z. (2013). "Effects of the thickness of the heat-treated wood specimen on water-soluble extractives and mechanical properties of merbau heartwood," BioRes. 8(1), 603-611.AbstractArticlePDF

    Merbau wood has a disadvantage in outdoor applications because its water-soluble extractives readily leach out and stain adjacent materials. This study examined the thickness of the heat-treated wood specimen on water-soluble extractives and some mechanical properties. The results show that heat treatment is efficient at removing the water-soluble extractives of merbau heartwood and overcoming the leaching problem. The absorbance of UV light decreased in intensity when the duration of heating was increased from 1 hour to 5 hours. The dominant absorbance peak increased from the surface layer to the core layer. The modulus of elasticity (MOE) and modulus of rupture (MOR) of heat-treated samples showed significant reductions when the heating duration exceeded a certain point. The total loss of mass during heat treatment and water extraction verified that heat treatment removes the water-soluble extractives efficiently.

  • Researchpp 628-637Si, C.-L., Liu, S.-C., Hu, H.-Y., Jiang, J.-Z., Yu, G.-J., Ren, X.-D., and Xu, G.-H. (2013). "Activity-guided screening of the antioxidants from Paulownia tomentosa var. tomentosa bark," BioRes. 8(1), 628-637.AbstractArticlePDF

    Tree barks, as a type of forestry residues, are a rich and renewable bioresource that can produce high value-added products. Paulownia tomentosa var. tomentosa (PTT) has been extensively used in traditional Chinese medicine to cure various diseases. However, the antioxidative activity of the chemical constituents of the tree has not yet been investigated. In this study, the bark of PTT were extracted and fractioned. Then the resulting ethyl acetate (EtOAc) soluble fraction, which exhibited the strongest antioxidative effect, was subjected to repeated open column chromatography for purification. The screening process was carried out under the guidance antioxidative activity via diphenylpicrylhydrazyl (DPPH) radical scavenging assay. Eight phenolic compounds, glucodistylin (I), luteolin (II), ellagic acid (III), cistanoside F (IV), campneoside II (V), isocampneoside II (VI), verbascoside (VII), and isoverbascoside (VIII), were isolated and their structures were elucidated by various spectroscopic analyses. Among the phenolics, II~VIII showed significant antioxidative activity.

  • Researchpp 612-627Ko, C.-H., Shih, T.-L., Jhan, B.-T., Chang, F.-C., Wang, Y.-N., and Wang, Y.-C. (2013). "Production of xylooligosaccharides from forest waste by membrane separation and Paenibacillus xylanase hydrolysis," BioRes. 8(1), 612-627.AbstractArticlePDF

    Xylooligosaccharides (XO), derived from the alkaline (NaOH) extractant of Mikania micrantha, were produced using multiple staged membrane separation and enzymatic xylanolysis. Staged nanofiltration (NMX), ultrafiltration (EUMX), and centrifugation (EMX) processes for the ethanol precipitates were conducted. NMX recovered 97.26% of total xylose and removed 73.18% of sodium ions. Concentrations of total xylose were raised from 10.98 to 51.85 mg/mL by the NMX process. Recovered xylan-containing solids were hydrolyzed by the recombinant Paenibacillus xylanase. 68% XO conversions from total xylose of NMX was achieved in 24 hours. Xylopentaose (DP 5) was the major product from NMX and EMX hydrolysis. Xylohexaose (DP 6) was the major product from EUMX hydrolysis. Results of the present study suggest the applicability for XO production by nanofiltration, as NMX gave higher XO yields compared to those from a conventional ethanol-related lignocellulosic waste conversion process.

  • Researchpp 638-647Liu, X., Liu, Z., Fei, B., Cai, Z., Jiang, Z., and Liu, X. (2013). "Comparative properties of bamboo and rice straw pellets," BioRes. 8(1), 638-647.AbstractArticlePDF

    Bamboo is a potential major bio-energy resource. Tests were carried out to compare and evaluate the property of bamboo and rice straw pellets, rice straw being the other main source of biomass solid fuel in China. All physical properties of untreated bamboo pellets (UBP), untreated rice straw pellets (URP), carbonized bamboo pellets (CBP), and carbonized rice straw pellets (CRP) met the requirements of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified including dimension, density, and strength. The inorganic ash (15.94 %) and gross heat value (15375 J/g) of rice straw pellets could not meet the requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (≤6.0% for PFI Utility) and the minimum requirement for making commercial pellets of DIN 51731 (>17500 J/g), respectively. Rice straw pellets have been a main type of biomass solid fuel and widely used. Bamboo pellets have better combustion properties compared with rice straw pellets. It is confirmed that bamboo pellets have great potential as biomass solid fuel, especially with respect to development of commercial pellets on an industrial scale in China. The information provided by this research is useful for development and utilization of bamboo resource and pellets.

  • Researchpp 648-662Zheng, C.-Y., Tao, H.-X., and Xie, X.-A. (2013). "Distribution and characterizations of liquefaction of celluloses in sub- and super-critical ethanol," BioRes. 8(1), 648-662.AbstractArticlePDF

    Effects of reaction conditions (temperature, retention time, and cellulose/ ethanol ratio) on biomass liquefaction in sub- and super-critical ethanol were investigated in this work. The liquefaction system was divided into the following fractions: a volatile organic compounds fraction, a gas fraction, a heavy oil fraction, a water-soluble oil fraction, and a solid residue fraction. Results showed that for three samples, the SR yield of microcrystalline cellulose was highest compared with corn stalk cellulose and rice straw cellulose at the same temperature, while the HO yield was lowest in the liquefaction process. At the same retention time in super-critical ethanol, the SR yield of microcrystalline cellulose was highest, suggesting that the microcrystalline cellulose was difficult to liquefy. The effect of different samples on liquefaction in ethanol with various cellulose/ethanol ratios can be clearly seen from the distribution yields. The FT-IR analysis of the solid residues showed that the structure of celluloses changed after liquefaction. The GC-MS analysis showed that the volatile organic compounds, water-soluble oil, and heavy oil comprised a mixture of organic compounds, which mainly included furfural, acids, furans, esters, and their derivatives. XRD analysis revealed that the decomposing reaction primarily occurred within amorphous zones of the celluloses at the low temperatures.

  • Researchpp 663-675Hu, J., Lei, T., Shen, S., and Zhang, Q. (2013). "Specific energy consumption regression and process parameters optimization in wet-briquetting of rice straw at normal temperature," BioRes. 8(1), 663-675.AbstractArticlePDF

    In the normal-temperature (20 to 25 ˚C) wet briquetting of straw, the lignin becomes softened and briquetted by means of friction heat from the briquetting at some compressing force and moisture ratio. With an electronic universal testing machine and a self-developed normal- temperature wet briquetting device, tests were carried out for normal-temperature wet briquetting of rice straws with different compressing rate, material moisture, die length-diameter ratio, and die opening taper, using a quadratic regression-orthogonal design. Based on the characteristic curves of normal-temperature wet briquetting, the specific energy consumption was calculated by stepped regression and then integration for summation. Thereby, a specific energy consumption model was established. Next, an interactive analysis was made between single-factor and two-factor designs. Optimal combination of factors, i.e. 17.3% moisture, 44.5 mm/min compressing rate, 45˚ die opening taper, and 5.3 die length-diameter ratio, were obtained while the specific energy consumption was minimized. Further, the work provided references for process parameters design of the normal-temperature wet briquetting device for straw.

  • Researchpp 676-687Farhana Harun, N. A., Samsu Baharuddin, A., Mohd Zainudin, M. H., Bahrin, E. K., Naim, M. N., and Zakaria, R. (2013). "Cellulase production from treated oil palm empty fruit bunch degradation by locally isolated Thermobifida fusca," BioRes. 8(1), 676-687.AbstractArticlePDF

    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.

  • Researchpp 688-700Chiu, C.-M., Lin, C.-H., and Yang, T.-H. (2013). "Application of nondestructive methods to evaluate mechanical properties of 32-year-old Taiwan incense cedar (Calocedrus formosana) wood," BioRes. 8(1), 688-700.AbstractArticlePDF

    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.

  • Researchpp 701-716Premjet, S., Pumira, B., and Premjet, D. (2013). "Determining the potential of inedible weed biomass for bio-energy and ethanol production," BioRes. 8(1), 701-716.AbstractArticlePDF

    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.


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