NC State
  • Researchpp 1372-1395Quintero, O. L., Amicarelli, A. A., Scaglia, G., and di Sciascio, F. (2009). "Control based on numerical methods and recursive Bayesian estimation in a continuous alcoholic fermentation process," BioRes. 4(4), 1372-1395.AbstractPDF
    Biotechnological processes represent a challenge in the control field, due to their high nonlinearity. In particular, continuous alcoholic fermentation from Zymomonas mobilis (Z.m) presents a significant challenge. This bioprocess has high ethanol performance, but it exhibits an oscillatory behavior in process variables due to the influence of inhibition dynamics (rate of ethanol concentration) over biomass, substrate, and product concentrations. In this work a new solution for control of biotechnological variables in the fermentation process is proposed, based on numerical methods and linear algebra. In addition, an improvement to a previously reported state estimator, based on particle filtering techniques, is used in the control loop. The feasibility estimator and its performance are demonstrated in the proposed control loop. This methodology makes it possible to develop a controller design through the use of dynamic analysis with a tested biomass estimator in Z.m and without the use of complex calculations.
  • Researchpp 1409-1416Zeinaly, F., Shakhes, J., Firozabadi, M. D., and Shakeri, A. (2009). "Hydrogen peroxide bleaching of CMP pulp using magnesium hydroxide," BioRes. 4(4), 1409-1416.AbstractPDF
    Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH)2) show significant benefits over bleaching with sodium hydroxide (NaOH) under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF) were more for the Mg(OH)2-based process. The residual peroxide of filtrate from the Mg(OH)2-based process was very high as compared to conventional bleaching.
  • Researchpp 1417-1429Erakhrumen, A. A., and Ogunsanwo, O. Y. (2009). "Water absorption, anti-swell efficiency, and dimensional stability properties of neem seed-oil treated wild grown Bambusa vulgaris Schard. ex J. C. Wendl. in southwest Nigeria,"BioRes. 4(4), 1417-1429.AbstractPDF
    Bamboo culm is a hygroscopic lignocellulosic material. Hygroscopic properties may be disadvantageous in bamboo material if applied in certain applications and modes where and when extreme moisture variations are likely to occur. This study was aimed at evaluating the moisture absorption and resistance including dimensional stability properties of neem seed oil-treated split bamboo samples using two methods of treatment. Split bamboo samples from the same source were oven-dried at 103±2oC, conditioned to 11.76% mean moisture content, and treated by completely soaking them in oil at room temperature for 24 hours and by soaking in hot oil at 60oC for 4 hours, with untreated samples as control. Results showed that samples soaked in hot oil at 60oC for 4 hours had both the least percentage water absorption and higher anti-swell efficiency, followed by samples soaked in oil at room temperature for 24 hours. Shrinkage in the longitudinal, radial, and tangential directions also followed the same trend. Conclusions and recommendations were made in line with the outcome of the study.
  • Researchpp 1430-1454Brännström, M. (2009). "The impact of a strength grading process on sawmill profitability and product quality," BioRes. 4(4), 1430-1454.AbstractPDF
    A strength grading process, starting with log grading, was studied with respect to grading yield, impact on quality, and economic efficiency when visual grades according to Nordic grading rules were used for alternate product comparison. Pine (Pinus sylvestris) and spruce (Picea abies) logs and boards were graded with several varieties of commercial grading and strength-grading equipment. The boards were destructively tested, and the European grade-determining properties strength, stiffness, and density were measured. Models for these were made by partial least squares and validated. A method for the derivation of settings for multiple indicating properties, which increased yield in some cases, was proposed and evaluated. Grading to grade combinations of C40, C30, and C18 was done. The impact of visual override based on deformations was also studied. A simplified economic and sensitivity analysis was done. The outcome was that log grading can be used for strength grading with good economic and quality results. Strength pregrading on logs improves sawmill economy, depending on the species and market situation. Drying quality greatly influences the yield through visual override grading on deformations. Market prices of high grades (>C30) must improve in order to stimulate supply, as it is more economical to produce lower grades.
  • Researchpp 1455-1476Saw, S. K., and Datta, C. (2009). "Thermomechanical properties of jute/bagasse hybrid reinforced epoxy thermoset composites," BioRes. 4(4), 1455-1476.AbstractPDF
    Natural fibres are partly replacing currently used synthetic fibres as reinforcement for polymer composites. Jute fibre bundles were high-cellulose-content modified by alkali treatment, while the bagasse fibre bundles were modified by creating quinones in the lignin portions of fibre surfaces and reacting them with furfuryl alcohol (FA) to increase their adhesiveness. The effects of different fibre bundle loading and modification of bagasse fibre surfaces in hybrid fibre reinforced epoxy composites have been studied. The role of fibre/matrix interactions in chemically modified hybrid composites were investigated using Differential Scanning Calorimeter, Differential Thermo Gravimetry, and a Universal Tensile Machine and compared with those of unmodified bagasse fibre bundles incorporated with modified jute fibre bundles reinforced hybrid composites. Fibre surface modification reduced the hydrophilicity of fibre bundles, and significantly increased mechanical properties of hybrid composites were observed in conjunction with SEM images. The SEM analysis of the fibre and the composite fractured surfaces have confirmed the FA grafting and shown a better compatibility at the interface between chemically modified fibre bundles and epoxy resin. This paper incorporates interesting results of thermomechanical properties and evaluation of fibre/matrix interactions.
  • Researchpp 1477-1486Wang, J., Chen, Y., Wang, X., and Cao, F. (2009). "Aluminum dodecatungstophosphate (Al0.9H0.3PW12O40) nanotube as a solid acid catalyst one-pot production of biodiesel from waste cooking oil," BioRes. 4(4), 1477-1486.AbstractPDF
    Solid nanocatalyst aluminum dodecatungstophosphate (Al0.9H0.3PW12O40, abbreviated as AlPW) with nanotube structure was synthesized through a natural cellulose fiber template. The AlPW nanotubes, which are highly water-tolerant and acid-tolerant, can be described as green double acids, as they combineand Lewis acid sites. They have been applied as an efficient nanoheterogeneous catalyst for the preparation of biodiesel from waste cooking oil containing 26.89 wt% high free fatty acids (FFAs) and 1% moisture via esterification of FFAs and transesterification of triglycerides in one pot under mild conditions.
  • Researchpp 1487-1497Wu, Y., Zhou, D.-G., Wang, S.-Q., and Zhang, Y. (2009). "Polypropylene composites reinforced with rice straw micro/nano fibrils isolated by high intensity ultrasonication," BioRes. 4(4), 1487-1497.AbstractPDF
    Rice straw (Oryza sativa L.) pulp was treated by high intensity ultrasonication to make fibrils. The rice straw fibril (RSF) material was used as reinforcement in an RSF/polypropylene (PP) composite. The influences of RSF and coupling agent (MAPP) contents on tensile properties of the composite were tested. The results showed that when RSF loading was 5%, the tensile strength rose to a maximum value of 31.7 MPa. With increasing fibril loading the tensile modulus increased first, then decreased. However, the elongation at break decreased with increasing fibril loading. There was no significant influence of MAPP content on tensile strength and elongation at break of PP and RSF/PP composite. When MAPP content was 4%, the tensile modulus of PP and RSF/PP composite all showed maximum values.
  • Researchpp 1498-1519Shen, J., Song, Z., Qian, X., and Liu, W. (2009). "Modification of precipitated calcium carbonate filler using sodium silicate/zinc chloride based modifiers to improve acid-resistance and use of the modified filler in papermaking," BioRes. 4(4), 1498-1519.AbstractPDF
    In order to improve the acid-resistant property of papermaking grade precipitated calcium carbonate filler and to obtain modified filler in powder form, sodium silicate/zinc chloride based modifiers were used in filler modification, and the use of modified filler in papermaking of deinked pulp derived from recycled newspaper was also preliminarily investigated. Under the preliminarily optimized experimental conditions, when sodium silicate, zinc chloride, sodium hexametaphosphate, and phosphoric acid with dosages of 10 wt%, 3 wt%, 1 wt% and 0.2 wt%, respectively, were used as modifiers, and when the temperature, aging time, and PCC concentration during the filler modification process was 70 oC, 7 h and 9.1 wt%, respectively, the acid-resistant property of filler was significantly improved after modification, as evaluated using alum consumption and pH methods. The use of modified precipitated calcium carbonate filler prepared under the optimized conditions provided considerably more brightness and light scattering improvement in comparison to unmodified filler, and filler modification was found to have only negligible influence on tensile and burst strength of the paper, air permeability of the paper, and retention performance of the filler. Surface analysis of the modified filler using XPS and SEM confirmed the occurring of surface encapsulation and modification of precipitated calcium carbonate filler when the relevant modifiers were used in filler modification. The encapsulating effect of modifiers on filler was thought to be favorable to improvement in acid-resistant property, and optical properties of the filled paper.
  • Researchpp 1520-1535Li, J., Xiao, B., Yan, R., and Liu, J. (2009). "Development of a nano-Ni-La-Fe/Al2O3 catalyst to be used for syn-gas production and tar removal after biomass gasification," BioRes. 4(4), 1520-1535.AbstractPDF
    The objective of this study was to develop a supported tri-metallic catalyst (nano-Ni-La-Fe/γ-Al2O3) for tar removal in biomass steam gasification, to significantly enhance the quality of the produced gas. For this purpose, the supported tri-metallic catalysts were prepared by a deposition-precipitation (DP) method. Different analytical approaches were used to characterize the synthesized catalysts. The results showed that the prepared tri-metallic catalysts had an egg-shell structure with a specific surface area of 214.7 m2/g. The activity of the catalysts for gas production and tar removal in the process of biomass gasification was also investigated using a bench-scale combined fixed bed reactor. The experiments indicated that the tar yield after adding catalyst was reduced significantly and the efficiency of tar removal reached 99% for the biomass steam gasification at 800oC, while the gas yield after adding catalysts increased markedly and less coke was found over the catalyst. Meanwhile, the compositions of gas products before and after adding catalyst in the process also changed significantly; in particular, the content of hydrogen in catalytic steam gasification was improved by over 10 vol%. Therefore, using the prepared tri-metallic catalyst in biomass gasification can significantly improve the quality of the produced gas and efficiently eliminate the tar generation, preventing coke deposition on the catalyst surfaces, thus demonstrating a long lifetime of the catalyst.
  • Researchpp 1536-1544Ayrilmis, N., Dundar, T., Candan, Z., and Akbulut, T. (2009). "Wettability of fire retardant treated laminated veneer lumber (LVL) manufactured from veneers dried at different temperatures," BioRes. 4(4), 1536-1544.AbstractPDF
    Wettability of the fire retardant treated (FRT) laminated veneer lumber (LVL) manufactured from wood veneers dried at different temperatures was investigated. Commercially manufactured veneer of beech wood (Fagus orientalis L.) was treated with borax-boric acid (BX/BA, 1:1 by weight), monoammonium phosphate (MAP), and diammonium phosphate (DAP) using a full-cell pressure process. The veneers were then dried at different temperatures (120, 140, 160, and 180°C), and experimental LVLs were made from these veneer sheets. The wettability of LVL was characterized by contact angle analysis. The lowest contact angle was obtained from LVL made from BX/BA-treated veneers, while the highest value was found for the control LVL. The CA values of these samples at each re-drying level were lower than LVLs made from untreated veneers. Re-drying of the treated veneers decreased the CA values of the LVL, while it was found higher for the LVL made from untreated veneer.