NC State
  • Researchpp 2539-2550Guo, Z., Wang, S., Xu, G., and Cai, G. (2011). "Upgrading of bio-oil molecular distillation fraction with solid acid catalyst," BioRes. 6(3), 2539-2550.AbstractArticlePDF

    Molecular distillation technology has been adopted to obtain a bio-oil fraction rich in carboxylic acids and ketones. This unique bio-oil fraction was then upgraded with a La-promoted solid acid catalyst. Three washing pretreatments were used to prepare catalysts A, B, and C, with the intention of reducing the amounts of residual sulfuric acid. Model reactions were used to estimate their catalytic activities and the residual amounts of sulfuric acid. Catalyst B, with washing after calcination, displayed higher catalytic activity (80.83%) and lower residual amount of sulfuric acid (50 μmol/g). The catalysts were characterized by techniques such as BET, XRD, and SEM to explain the differences in their catalytic activities. The optimum catalyst B was used in the upgrading of the bio-oil molecular distillation fraction. After upgrading, the corrosivity of the bio-oil fraction declined and its storage stability was improved. The carboxylic acid content in the upgraded bio-oil fraction decreased from 18.39% to 2.70%, while the ester content increased from 0.72% to 31.17%. The conversion of corrosive carboxylic acids to neutral esters reduced the corrosivity of the bio-oil fraction. Moreover, the ketones with unsaturated carbon-carbon double bonds (such as 2-cyclopenten-1-one, 3-methyl-2-cyclopenten-1-one, etc.) were converted into saturated compounds, which improved the stability of the bio-oil fraction.

  • Researchpp 2551-2567Gonzalez, R., Treasure, T., Phillips, R., Jameel, H., and Saloni, D. (2011). "Economics of cellulosic ethanol production: Green liquor pretreatment for softwood and hardwood, greenfield and repurpose scenarios," BioRes. 6(3), 2551-2567.AbstractArticlePDF

    Green liquor pretreatment, a technology presently used worldwide in hundreds of kraft pulp mills, is proposed in this work as a potential pretreatment pathway for the efficient conversion of lignocellulosic biomass into ethanol. Mixed southern hardwood, eucalyptus, and loblolly pine were evaluated through process simulations in two investment scenarios: a greenfield mill scenario and a repurposing scenario, using existing kraft pulp mill assets for cellulosic ethanol production. Several advantages come with this concept: i) proven technology (both process and equipment), ii) chemical and energy recovery in place, iii) existing fiber supply chain, and iv) experienced labor force around the mill. Ethanol yields through enzymatic hydrolysis of pretreated fibers were highest in natural mixed hardwood and eucalyptus (280-285 liters of ethanol per dry ton of biomass) and lowest in loblolly pine (273 liters per dry ton of biomass). Natural hardwood and eucalyptus in the repurposing scenario form the most profitable combinations with an IRR of about 19%, mainly due to low capital expenditure (CAPEX) (per liter of ethanol), low enzyme costs, and higher ethanol yield (compared to loblolly pine). Production cost (in the repurposing scenario) was estimated at $2.51 per gallon of ethanol (or $0.66 per liter), cash cost at $2.14 gallon-1 (or $0.57 per liter), and CAPEX at $3.15 gallon-1 (or $0.83 per liter). Repurposing existing closed mills creates a potential alternative to ramp up in the task of producing alternative lignocellulosic biofuels.

  • Researchpp 2568-2580Yang, G., Lucia, L. A., Chen, J., Cao, X., and Liu, Y. (2011). "Effects of enzyme pretreatment on the beatability of fast-growing poplar APMP pulp," BioRes. 6(3), 2568-2580.AbstractArticlePDF

    Effects of enzyme pretreatment on the properties of fast-growing poplar APMP pulp were evaluated. Compared with the unpretreated pulp, the beatabilities of the pulp that had been pretreated by enzymes were improved significantly, such as a decrease of Canadian Standard Freeness (CSF) in the range of 25 mL to 55 mL, a decrease of PFI mill revolutions from 1000r to 5500r, and a decrease of beating energy consumption from 12.5% to 22.0%. The values of brightness, breaking length, tearing index, bursting index, and folding number of the pulp pretreated by cellulase were improved by 1.2%ISO, 23.7%, 14.8%, 14.6%, and 50% respectively, while that of the pulp pretreated by xylanase were respectively improved by 2.1%ISO, 16.8%, 8.8%, 8.9%, and 25%. The optimal enzyme dosages were 25 IU•g-1 and 25IU•g-1 for cellulase and xylanase, respectively. Fibre quality analysis results showed that the fibre length of pretreated pulp increased partly, fibre width and fines content decreased, fibres torsion increased, and fibre bonding got stronger. X-ray diffractometer analysis indicated that the degree of crystallinity of fibres increased after the enzyme pretreatment.

  • Researchpp 2581-2591Javed, M. A., and Germgård, U. (2011). "The reactivity of prehydrolyzed softwood kraft pulps after prolonged cooking followed by chlorite delignification," BioRes. 6(3), 2581-2591.AbstractArticlePDF

    In a laboratory study high-quality spruce chips were prehydrolyzed to remove hemicelluloses and then kraft cooked to different kappa numbers by varying the cooking time. Each pulp sample was then chlorite delignified to selectively remove the remaining lignin. The reactivities of the pulp samples before and after chlorite delignification were determined by Fock’s test, which is supposed to measure the pulp’s reactivity in the conventional viscose process. A number of analyses were carried out to determine which parameters affected pulp reactivity, as, for example: intrinsic viscosity, kappa number, pulp yield, carbohydrate composition, levelling-off degree of polymerization (LODP), and alkali solubility. The results of the study showed that the pulp reactivity increased with decreasing kappa number, and the highest reactivity was obtained after total lignin removal using chlorite delignification. It was also found that the carbohydrate composition had no influence on the pulp reactivity, but lower intrinsic viscosity either obtained by prolonged cooking or chlorite delignification correlated with higher pulp reactivity. Finally, lower alkali solubility, i.e. higher R18, reduced the reactivity.

  • Researchpp 2592-2604Liu, H.-M., Xie, X.-A., Feng, B., and Sun, R.-C. (2011). "Effect of catalysts on 5-lump distribution of constalk liquefaction in sub-critical ethanol," BioRes. 6(3), 2592-2604.AbstractArticlePDF

    Liquefaction of cornstalk in sub-critical solution of ethanol without and with catalysts (K2CO3, Na2CO3 and ZnCl2) was performed in a stainless steel reactor (1 L) at temperatures of 200 to 300 oC. The cornstalk and the products of decomposition were divided into five lumps (gas, organic dissolved, heavy oil, volatile organic compounds, and residue). The effects of reaction temperature and the catalyst amount on the five lump yields were studied. The bio-oils produced with and without catalysts were characterized by GC/MS. Results showed that an increment in the temperature and the addition of catalysts had a synergetic effect on the lumps yield as compared to the non-catalytic experiments, and different catalytic procedures had an important effect on the lump yields and compounds of the bio-oils. The addition of the catalyst enhanced the gas yield and the total conversion rate. A high temperature, lower amount of Na2CO3, moderate amount of K2CO3, and a high amount of ZnCl2 were propitious to enhance the heavy oil. The formation of volatile organic compounds with the presence of ZnCl2 and K2CO3 was less than that in non-catalytic experiments at the higher temperatures. However, a higher conversion temperature had a negative impact on the bio-oils yield from liquefaction of cornstalk with and without catalysts.

  • Researchpp 2605-2618Cui, L., Li, L., Zhang, A., Pan, G., Bao, D., and Chang, A. (2011). "Biochar amendment greatly reduces rice Cd uptake in a contaminated paddy soil: A two-year field experiment," BioRes. 6(3), 2605-2618.AbstractArticlePDF

    A field experiment was conducted on the effect of biochar (BC) amendment on Cd uptake by rice (Oryza sativa L.) in a contaminated paddy in 2009 and 2010. BC was applied as a basal soil amendment before rice transplantation in 2009 at rates of 0, 10, 20, 40t ha-1, and rice yield and Cd uptake were monitored in both 2009 and 2010. The BC amendment significantly increased soil pH by 0.15-0.33 units in 2009 and 0.24-0.38 units in 2010, and decreased CaCl2 extracted Cd in soil by 32.0%-52.5% in 2009 and 5.5%-43.4% in 2010, respectively. Under BC amendment at 10, 20, 40 t ha-1, rice grain Cd concentration was observed to be reduced by 16.8%, 37.1%, and 45.0% in 2009 and by 42.7%, 39.9%, and 61.9% in 2010, while the total plant Cd uptake was found to decrease by 28.1%, 45.7%, and 54.2% in 2009 and by 14.4%, 35.9%, and 45.9% in 2010, respectively. Such effect of BC amendment on reducing Cd plant uptake has profound implications among those using bioresources for field application. Finally, BC amendment in combination with low Cd cultivars may offer a basic option to reduce Cd levels in rice as well as to reduce greenhouse gas emissions in rice agriculture in contaminated paddies.

  • Researchpp 2619-2631Dai, L., Dai, H., Yuan, Y., Sun, X., and Zhu, Z. (2011). "Effects of TEMPO oxidation system on kinetic constants of cotton fibers," BioRes. 6(3), 2619-2631.AbstractArticlePDF

    The kinetics of the TEMPO-mediated oxidation of cotton fibers were studied. It was revealed that the oxidation reaction of the cotton fibers by TEMPO/NaBr/NaClO system can be approximately described as two pseudo-first-order reaction kinetics that are based on the cellulose microstructure, namely the kinetic processes of the primary wall and the secondary wall. In the concentration range used in this study, the rate constant k was directly proportional to the concentration of TEMPO. As to NaBr, the rate constant was proportional to the concentration in a relatively lower range, while it tended to level off at higher concentration, but the oxidation reaction rate increased with concentration when the concentration was above 1.0 mmol/g. The pH value had a great impact on the oxidation rate; the optimum pH was controlled from 10 to 11. The effect of temperature on the rate constant could be well described by the Arrhenius equation, and the apparent activation energy measured was about 56.66kJ/mol. The X-ray diffraction pattern, which indicates the crystallinity of cotton fibers, was nearly constant during the oxidation.

  • Researchpp 2632-2646Abdolahian Sohi, A. M., Khademi-Eslam, H., Hemmasi, A. H., Roohnia, M., and Talaiepour, M. (2011). "Nondestructive detection of the effect of drilling on acoustic performance of wood," BioRes. 6(3), 2632-2646.AbstractArticlePDF

    The aim of this paper is to determine the effect of hole diameter (LR Direction) on acoustic performance indicators such as acoustic coefficient and acoustic conversion efficiency of wooden beams using flexural vibration of a free-free bar test.The drilling from 0 to 8 millimetres diameter was made exactly at the middle of the bar, on the node of the second mode of vibration. The results revealed that holes of diameter from 0 to 8 millimeters didn’t cause any sever change on acoustic coefficient and acoustic conversion efficiency when the beam was impacted on both radial and tangential surfaces. Nevertheless, these acoustic properties changed a bit when the beam was impacted on the tangential surface. Thus, the changes of the acoustic coefficient and acoustic conversion efficiency for both radial and tangential impacts were not significant, even with an 8 mm hole. Therefore, hole diameter not only didn’t cause any severe effect on acoustic coefficient and acoustic conversion efficiency but also somewhat increased their values. So, a hole having a relatively small diameter may cause improved acoustical performance of a wooden beam.

  • Researchpp 2647-2662El Mansouri, N.-E., Yuan, Q., and Huang, F. (2011). "Characterization of alkaline lignins for use in phenol-formaldehyde and epoxy resins," BioRes. 6(3), 2647-2662.AbstractArticlePDF

    Besides polyurethanes and polyesters, phenolic and epoxy resins are the most prominent applications for technical lignins in thermosetting materials. To evaluate the potential application of lignin raw materials in phenol formaldehyde and epoxy resins, three types of alkaline lignins were characterized in terms of their structures and thermal properties. The lignin samples analyzed were kraft lignin (LIG-1), soda–rice straw lignin (LIG-2), and soda-wheat straw lignin (LIG-3). FTIR and 1H-NMR methods were used to determine their structure. Gel permeation chromatography (GPC) was used to determine the molecular weight distribution (MWD). Differential scanning calorimetry (DSC) was used to measure the glass transition temperature (Tg), and thermogravimetric analysis (TGA) to determine the thermal stability of lignin samples. Results showed that kraft lignin (LIG-1) has moderate hydroxyl-group content, is rich in G-type units, and has good thermal stability. These properties make it more suitable for direct use in phenol formaldehyde resins, and it is therefore a good raw material for this purpose. The alkaline soda-rice straw lignin (LIG-2) with a high hydroxyl-group content and excellent thermal stability is most suited to preparing lignin-based epoxy resins.

  • Researchpp 2663-2675Shahriarinour, M., Ramanan, R. N., Abdul Wahab, M. N., Mohamad, R., Mustafa, S., and Ariff, A. B. (2011). "Improved cellulase production by Aspergillus terreus using oil palm empty fruit bunch fiber as substrate in a stirred tank bioreactor through optimization of the fermentation conditions," Biores. 6(3), 2663-2675.AbstractArticlePDF

    Response surface methodology (RSM) was performed to evaluate the effects of dissolved oxygen tension (DOT) and initial pH on the production of carboxymethyl cellulase (CMCase), filter-paper hydrolase (FPase), and β-glucosidase by Aspergillus terreus in a 2 L stirred tank bioreactor. Delignifiedoil palm empty fruit bunch (OPEFB) fibre was used as the main substrate under submerged fermentation. Growth of A. terreus and the production of three main components of cellulase were optimized by central composite design (CCD) design. Statistical analysis of results showed that the individual terms of these two variables (DOT and pH) had significant effects on growth and the production of all components of cellulase. Maximum growth (13.07 g/L) and cellulase activity (CMCase = 50.33 U/mL, FPase = 2.29 U/mL and β-glucosidase = 15.98 U/ml) were obtained when the DOT and initial culture pH were set at 55% and 5.5, respectively. A high proportion of β-glucosidase to FPase (8:1) in cellulase of A. terreus could be beneficial for efficient hydrolysis of cellulosic materials. The use of OPEFB as a main substrate would reduce the cost of fermentation for the production of cellulase.


54 years ago

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