Research Articles
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- Researchpp 557-570Barbaric-Mikocevic, Z., Plazonic, I., and Dzimbeg-Malcic, V. (2013). "The deinkability improvement of offset prints made from a two-side coated substrate," BioRes. 8(1), 557-570.AbstractArticlePDF
This paper describes the improved removal of impurities (coating, ink/toner) from offset prints produced by digital printing of two-side coated paper. The substrates were printed by conventional and digital offset processes. Based on image analysis results it was established that deinking flotation is an inefficient method for ink particle removal from digital offset printed paper, but it is efficient for ink removal from conventional offset printed paper. On the other hand, pre-treatment with hydrogen peroxide solution gives better results for ink particle removal from digital offset prints than from conventional offset prints. Optimal parameters for hydrogen peroxide pre-treatment for both offset prints were chosen based on unprinted substrate mass loss results in the preliminary investigation. These results showed that hydrogen peroxide pre-treatment is more successful at removal of impurities in comparison with flotation deinking without pre-treatment.
- Researchpp 571-580Wu, C.-L., Chang, H.-T., Hsui, Y.-R., Hsu, Y.-W., Liu, J.-Y., Wang, S.-Y., and Chang, S.-T. (2013). "Antioxidant-enriched leaf water extracts of Cinnamomum osmophloeum from eleven provenances and their bioactive flavonoid glycosides," BioRes. 8(1), 571-580.AbstractArticlePDF
The study was designed to investigate the antioxidant activities of water extracts of C. osmophloeum leaves from eleven provenances (CO1-CO11) and their bioactive phytochemicals. Results revealed that leaf water extracts contained antioxidant phytochemicals and showed efficacy as antioxidants. Among varied leaf water extracts, water extract of CO4 showed the highest total phenolic content (160.9 mg/g) and superior free radical scavenging ability with the IC50 values of 10.3 and 16.9 μg/mL for DPPH and superoxide radical scavenging assays, respectively. It was also found to exhibit the best metal chelating ability and reducing power. According to the multiple spectral analyses, bioactive phytochemicals of leaf water extracts were flavonoid glycosides, including kaempferol-7-O-rhamnoside and kaempferol-3,7-O-dirhamnoside. Leaf water extracts of C. osmophloeum with high performance of antioxidant efficacy have great potential as a natural daily supplement.
- Researchpp 581-591Shi, Z., Fu, F., Wang, S., He, S., and Yang, R. (2013). "Modification of Chinese fir with alkyl ketene dimer (AKD): Processing and characterization," BioRes. 8(1), 581-591.AbstractArticlePDF
A process for the chemical modification of Chinese fir with alkyl ketene dimer (AKD) was studied. The hydrophobicity of the resulting products was evaluated by characterization of the equilibrium moisture content, water-surface contact angle, water absorption coefficient, and anti-swelling efficiency. The results indicated that when 5% AKD solution was used, the modified wood generally showed good hydrophobicity and improved dimensional stability. The result of boiling water and hexane extraction tests showed that the modified fir possessed very stable hydrophobicity.
- 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 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 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 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.