NC State
  • Researchpp 4627-4638Wang, M., Zhang, Y., Yan, S., Yi, B., Niu, W., and Yuan, Q. (2017). "Enhanced biogas yield of Chinese herbal medicine extraction residue by hydrothermal pretreatment," BioRes. 12(3), 4627-4638.AbstractArticlePDF

    Chinese herbal medicine extraction residue (CHER) is a special organic waste produced in China. Because of the high content of lignocelluloses, CHER have a weak bioconversion efficiency for bio-products production. This study investigates the effect of a hydrothermal pretreatment (HTP, 140 to 220 °C, 15 min) on the organic matter solubilisation, biochemical methane potential, and methanation kinetics of CHER during anaerobic digestion (AD). The AD test was conducted with 5 g/L total solid at 35 °C for 30 d. The results showed that the HTP clearly improved the solubilisation of CHER, and the obtained soluble COD (%) reached over 30% (only 4.5% in untreated). Acetic acid, xylose, and glucose were found to be the main products in the hydrolysate. The methane yield and methanation speed of the treated CHER were also enhanced. The highest methane yield of 306 mL/g volatile solid was achieved at a HTP temperature of 180 °C, while the untreated control was only 175 mL/g VS. Moreover, a carbonisation phenomenon was observed at HTP temperatures over 200 °C, which resulted in a loss of organic matter and methane yield.

  • Researchpp 4639-4651Shao, L., You, T., Wang, C., Yang, G., Xu, F., and Lucia, L. A. (2017). "Catalytic stepwise pyrolysis of technical lignin," BioRes. 12(3), 4639-4651.AbstractArticlePDF

    The stepwise pyrolysis of technical lignin with and without a catalyst was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin was first pyrolyzed at 260 or 360 °C, and then the residue was subsequently pyrolyzed at 650 °C. It was found that stepwise pyrolysis of lignin concentrated the phenolic compounds in lignin-derived bio-oil. In a stepwise 260 to 650 °C process, the maximum total phenolic compounds were 86.2%. Among the phenolic compounds, guaiacol-type and phenol-type phenolic compounds were predominant. Further addition of a catalyst (HZSM-5) in the stepwise pyrolysis process enhanced control over the product distribution through conversion of phenolic compounds into aromatic hydrocarbon products. The aromatic hydrocarbons achieved the highest yield of 30.4% in the catalytic stepwise 260 to 650 °C process.

  • Researchpp 4652-4669Zhang, Y., Ma, Z., Zhang, Q., Wang, J., Ma, Q., Yang, Y., Luo, X., and Zhang, W. (2017). "Comparison of the physicochemical characteristics of bio-char pyrolyzed from moso bamboo and rice husk with different pyrolysis temperatures," BioRes. 12(3), 4652-4669.AbstractArticlePDF
    Bio-char pyrolyzed from biomass waste has been notably applied in various industries due to its versatile physicochemical characteristics. This paper investigated the difference of the properties of the bio-char derived from moso bamboo and rice husk under different pyrolysis temperatures (200 °C to 800 °C). As the temperature increased, the bio-char yield for both bamboo bio-char (BC) and rice husk bio-char (RHC) decreased, while the carbon element content and fixed carbon, the value of higher heating value (HHV) and pH increased for both BC and RHC. At 800 °C, BC had a higher HHV of 32.78 MJ/kg than RHC of 19.22 MJ/kg, while RHC had a higher yield of char (42.99 wt.%) than BC (26.3 wt.%) because of the higher ash content (47.51 wt.%) in RHC. SiO2 was the dominant component in the ash of RHC, accounting for 86.26 wt.%. The surface area (SBET) of RHC (331.23 m2/g) was higher than BC (259.89 m2/g). However, the graphitization degree of BC was higher than RHC at the same temperature. The systematic study on the evolution of the basic properties of BC and RHC will provide a good reference for their high value-added application.
  • Researchpp 4670-4689Meekum, U., and Kingchang, P. (2017). "Compounding oil palm empty fruit bunch/cotton fiber hybrid reinforced poly(lactic acid) biocomposites aiming for high-temperature packaging applications," BioRes. 12(3), 4670-4689.AbstractArticlePDF

    The manufacture of poly(lactic acid) (PLA) composites reinforced with both oil palm empty fruit bunch (EFB) and cotton fiber was investigated. The positive and significant effect of EFB on the heat distortion temperature (HDT) and flexural properties was determined by a 2k design of experiment study. Adding solid epoxy into the PLA matrix manifested inferior mechanical properties with no improvement to the HDT. The HDT and mechanical properties of the biocomposites were further improved by using an EFB/cotton hybridized system. The PLA/hybridized EFB/cotton biocomposites showed biodegradability and an HDT higher than 100 °C. However, the flowability of the material was retarded at high cotton fractions. Finally, adding talc filler into the biocomposites improved the flowability of the hybridized biocomposite systems, especially at low fiber and high talc contents. Nevertheless, inferior mechanical properties of the biocomposites were found for high talc and low fibers’ contents.

  • Researchpp 4690-4706Xie, L., He, G., Wang, X., Gustafsson, P. J., Crocetti, R., Chen, L., Li, L., and Xie, W. (2017). "Shear capacity of stud-groove connector in glulam-concrete composite structure," BioRes. 12(3), 4690-4706.AbstractArticlePDF

    A timber-concrete composite structure (TCC) is economically and environmentally friendly. One of the key design points of this kind of structure is to ensure the reliability of the shear connectors. The objective of this paper is to study the mechanical property of stud-groove-type connectors and to provide shear capacity equations for stud-groove connectors in timber-concrete composite structures. Based on the Johansen Yield Theory (European Yield Model), some mechanical models and capacity equations for stud-groove-type connectors in timber-concrete structures were studied. Push-out specimens with different parameters (stud diameter, stud length, groove width, and groove depth) were tested to obtain the shear capacity and slip modulus. The experimental strengths were used to validate equations given in the paper. The shear capacity and slip modulus of stud-groove-type connectors was in direct proportion to the diameter of studs and the dimension of the groove. Comparison between the theoretical and the experimental shear strength results showed reasonable agreement. The highlight of this study on shear capacity equations could significantly reduce the push-out tests before investigating the other properties of TCC.

  • Researchpp 4707-4721Shi, S., Zhou, X., Chen, W., Wang, X., Nguyen, T., and Chen, M. (2017). "Thermal and kinetic behaviors of fallen leaves and waste tires using thermogravimetric analysis," BioRes. 12(3), 4707-4721.AbstractArticlePDF
    Thermal decomposition characteristics and kinetic parameters of fallen leaves (FLs), waste tires (WTs), and their blends (1:1 weight ratio) were investigated. Pyrolysis experiments were conducted with four different heating rates of 5 °C/min, 10 °C/min, 20 °C/min, and 40 °C/min from 35 °C to 800 °C in a nitrogen atmosphere using a thermogravimetric analysis (TGA). The thermogravimetry/derivative thermogravimetry (TG/DTG) curves indicated that the three samples were mainly degraded in a wide temperature range of 350 °C to 450 °C, and that a greater weight loss rate corresponded to a higher heating rate. An elemental analysis demonstrated that FLs/WTs blends embraced a maximum calorific value that reached 25.24 MJ/kg. Two model-free methods, iso-conversional Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) were applied on the TGA data of samples to calculate the activation energies. The results showed that the average activation energies of the same feedstock based on KAS and FWO methods were approximately the same, with the highest error within 1.6%. Then, the activation energies obtained were introduced in the Coats/Redfern (CR) model-fitting method to derive the pre-exponential factors, based on first order rate of reaction.
  • Researchpp 4722-4736Ma, Y., Wang, C., and Chu, F. (2017). "Effects of fiber surface treatments on the properties of wood fiber-phenolic foam composites," BioRes. 12(3), 4722-4736.AbstractArticlePDF

    Wood fibers were modified with alkaline solution and silane coupling agent to study changes on the fiber surface and the influence of these treatments on the mechanical properties, flame resistance, thermal conductivity, and microstructure of wood fiber-phenolic foam composites. Test results indicated that the lignin, waxes, hemicelluloses, and other impurities from the fiber surface were partially dissolved and removed. The mechanical properties of treated wood fiber-phenolic foam composites increased dramatically, the cellular pore distribution was more regular, the size of bubble cells was smaller and more uniform, and the thermal conductivity was reduced, and, in particular, the fragility of treated wood fiber-phenolic foam composites decreased. However, with increasing wood fiber content, the mechanical properties and limited oxygen index (LOI) of composite foam decreased. By comprehensive analysis, it was shown that the interfacial compatibility between the fibers and phenolic resin was improved. Nevertheless, the amount of wood used could not be too high, and the optimum amount was approximately 5%.

  • Researchpp 4737-4753Liu, H., Zhu, J. Q., Li, X., Li, H. Z., Qin, L., Li, H., Wang, X., Bai, X., Li, W. C., Li, B. Z., and Yuan, Y. J. (2017). "Hybridization improves inhibitor tolerance of xylose-fermenting Saccharomyces cerevisiae," BioRes. 12(3), 4737-4753.AbstractArticlePDF

    Although some engineered S. cerevisiae strains exhibit good xylose utilization ability, the lack of tolerance to inhibitors generated in biomass pretreatment limits the application of such strains in the production of bioethanol from lignocellulosic biomass. By applying a sexual mating method, inhibitor tolerance was developed in xylose-utilizing strains. The final ethanol concentrations in simultaneous scarification and co-fermentation (SScF) process at 38 °C with hybrid strains were 50% higher than the SScF process with the xylose-fermenting parent strain. The strain viability of the hybrid strain E7-12 at 24 h was 282 times higher than the parent strain in the SScF process at 25% solid loading. Due to the improved sugar utilization, the final ethanol concentration reached 69.7 g/L (E7-11) and 70.0 g/L (E7-12), which were 25.3 g/L and 25.6 g/L higher than that of SScF with the xylose-fermenting strain, respectively.

  • Researchpp 4754-4775Young, T. M., Han, L. D., Perdue, J. H., Hargrove, S. R., Guess, F. M., Huang, X., Chen, C. H. (2017). "Impact of trucking network flow on preferred biorefinery locations in the southern United States," BioRes. 12(3), 4754-4775.AbstractArticlePDF

    The impact of the trucking transportation network flow was modeled for the southern United States. The study addresses a gap in existing research by applying a Bayesian logistic regression and Geographic Information System (GIS) geospatial analysis to predict biorefinery site locations. A one-way trucking cost assuming a 128.8 km (80-mile) haul distance was estimated by the Biomass Site Assessment model. The “median family income,” “timberland annual growth-to-removal ratio,” and “transportation delays” were significant in determining mill location. Transportation delays that directly impacted the costs of trucking are presented. A logistic model with Bayesian inference was used to identify preferred site locations, and locations not preferential for a mill location. The model predicted that higher probability locations for smaller biomass mills (feedstock capacity, the size of sawmills) were in southern Alabama, southern Georgia, southeast Mississippi, southern Virginia, western Louisiana, western Arkansas, and eastern Texas. The higher probability locations for large capacity mills (feedstock capacity, the size for pulp and paper mills) were in southeastern Alabama, southern Georgia, central North Carolina, and the Mississippi Delta regions.

  • Researchpp 4776-4794Guo, H., Lin, C., Wang, S., Jiang, D., Zheng, B., Liu, Y., and Qin, W. (2017). "Characterization of a novel laccase-producing Bacillus sp. A4 and its application in Miscanthus degradation," BioRes. 12(3), 4776-4794.AbstractArticlePDF
    Bacillus sp. A4 exhibiting laccase production was isolated from forest soil. Its laccase secreted into a LB medium exhibited a maximum activity of 3.9 U mg-1 protein at the optimal temperature (37 °C) and pH (6.0). The purified laccase of Bacillus sp. A4 demonstrated a low molecular mass of 33 kDa, and its optimal temperature and pH were 40 °C and 4.6, respectively, when using ABTS as a substrate. The activity of the purified laccase was significantly increased in the presence of Cu2+, methanol, and ethanol, but it was totally inhibited by L-cysteine. The laccase production of this strain was markedly stimulated when the strain was incubated with 0.5% different lignocellulosic biomasses. The highest activity of laccase (22.6 U mg-1 protein) was obtained in using algal biomass. This new strain efficiently decreased the lignin content of lignocellulose biomasses after 9 d of incubation at 37 °C, especially lignin from grasses. Further analysis showed that, compared to that of all tested biomasses, the new strain was a more efficient decomposer of the lignin of Miscanthus, which exhibited much more lignin loss and cell wall structure destruction in a short span of time. Therefore, the potential use of this strain could be advantageous for using lignin in Miscanthus for industrial processes.