NC State
  • Editorialpp 1 - 2Hubbe, M. A. (2007). "Incinerate, recycle, or wash and reuse," BioRes. 2(1), 1-2.AbstractPDF
    What is the best way to minimize the environmental impact of using a product such as paper? Three debating teams were formed within a university class. One team advocated increased recycling of paper. Another team pointed to evidence showing reduced environmental impact and lower net CO 2 emissions if the paper is incinerated rather than recycled. A third team advocated the replacement of paper by items such as porcelain plates and video screens, cutting costs and reducing waste by multiple reuse.
  • Researchpp 3 - 19Bi, W., and Coffin, D. W. (2007). "Racking strength of paperboard based sheathing materials," BioRes. 2(1), 3-19.AbstractPDF
    Small-scale racking testers were developed for use as a means to evaluate paperboard-based sheathing materials used in framed wall-construction. For the purpose of evaluating the performance of different sheathing materials, the tester provides an economic alternative to standard full-scale racking tests. In addition, results from testing provide practical insight into the racking response of framed and sheathed walls. The load-deformation responses of three commercial sheathing boards were measured, and initial racking stiffness and racking strength were proposed as parameters for characterizing the board. The racking test results showed that the initial paperboard racking stiffness correlated to elastic modulus and caliper, but the response was insensitive to paperboard orientation or test dimensions. Observations and results showed that both panel buckling and paperboard cutting at the staples affected the racking response, but the dominating factor influencing the racking response appears to be load transfer through the staples.
  • Researchpp 20-33Lee, J. M., Heitmann, J. A., and Pawlak, J. J. (2007). "Rheology of carboxymethyl cellulose solutions treated with cellulases," BioRes. 2(1), 20-33.AbstractPDF
    The effect of cellulase treatments on the rheology of carboxymethyl cellulose (CMC) solutions was studied using a rotational viscometer. The rheological behaviors of CMC solutions of different molecular mass and degrees of substitution where studied as a function of time after various treatments. These solutions were subjected to active and heat-denatured cellulase, a cationic polyelectrolyte (C-PAM), as well as different shear rates. A complex protein-polymer interaction was observed, leading to a potential error source in the measurement of enzymatic activity by changes in the intrinsic viscosity. The interaction was termed a polymeric effect and defined as a reduction in viscosity of the substrate solution without significant formation of reducing sugars from enzymatic hydrolysis. The cause of the reduction in viscosity appears to be related to the interaction between the enzymes as amphipathic particles and the soluble CMC. Thus, the polymeric effect may cause a considerable experimental error in the measurement of enzymatic activity by viscometric methods.
  • Researchpp 34-40Boeva-Spiridonova, R., Petkova, E., Georgieva, N., Yotova, L., and Spiridonov, I. (2007). "Utilization of a chemical-mechanical pulp with improved properties from poplar wood in the composition of packing papers," BioRes. 2(1), 34-40AbstractPDF
    The aim of the present work is to obtain a chemical-mechanical pulp (CMP) from poplar wood with improved properties, to be used in packing papers in place of more expensive softwood or hardwood pulp. For improving the CMP quality indicators, a preliminary treatment of the pulp has been carried out with a mixture of oxidizing enzymes produced from Phanerochaete chrysosporium, including lignin peroxidase, manganese peroxidase, and laccase. The two types of fiber materials obtained were double-stage bleached and then ground to 30oSR. It was found that preliminary enzyme treatment yielded CMP with improved physical, mechanical, and optical properties. The enzyme-pretreated CMP also refined faster, thus reducing the electricity consumption. Bleached CMP from poplar wood, obtained after preliminary enzyme treatment, could be successfully utilized at levels up to 40% in the composition of various packaging papers.
  • Researchpp 41-57Bodirlau, R., Spiridon, I., and Teaca, C. A. (2007). "Chemical investigation of wood tree species in a temperate forest east-northern Romania," BioRes. 2(1), 41-57.AbstractPDF
    A quantitative evaluation of wood chemical components for some tree species in a forest area from east-northern Romania is presented here, through a comparative study from 1964 to 2000. Investigation upon the wood tree-rings in a Quercus robur L. tree species, as a dominant species, as regards its chemical composition and structure of the natural polymer constituents - celluloseandlignin - was also performed through chemical methods to separate the main wood components, FT-IR spectroscopy, and thermogravimetry. Having in view the impact of climate and external factors (such as pollutant depositions), some possible correlations between wood chemical composition and its further use can be made. The FT-IR spectra give evidence of differences in the frequency domains of 3400-2900 cm-1 and 1730-1640 cm-1, due to some interactions between the chemical groups (OH, C=O). The crystallinity index of cellulose presents variations in the oak wood tree-rings. Thermogravimetry analyses show different behaviour of cellulose at thermal decomposition, as a function of radial growth and tree’s height. A preliminary chemical investigation of oak wood sawdust shows a relatively high content of mineral elements (ash), compared with a previous study performed in 1964, fact that may indicate an intense drying process of the oak tree, a general phenomenon present in European forests for this species.
  • Researchpp 58-65Betcheva, R. I., Hadzhiyska, H. A., Georgieva, N. V., and Yotova, L. K. (2007). "Biobleaching of flax by degradation of lignin with laccase," BioRes. 2(1), 58-65.AbstractPDF
    Research on lignin biodegradation has become of great interest, due to the fact that lignin is one of the most abundant renewable materials, next to cellulose. Lignin is also the substance that gives color to raw flax fibers. In order to bleach the flax and to keep its tenacity high enough for textile applications, it is necessary to remove the lignin and partially to preserve the pectin. Lignin and pectin are the main constituents of the layer which sticks the flax cells together within the multicellular technical fiber. White-rot fungi and their oxidative enzymes, laccases and peroxid-ases (lignin peroxidases and manganese peroxidases), are being applied for the biobleaching of papermaking pulp, thereby reducing the need for environmentally harmful chemicals. Some data also suggest that it is possible to use other phenolytic enzymes, such as pure laccase, for this purpose. The objective of the present work was to study the possibility of bleaching flax fibers by pure laccase and combined laccase peroxide treatment, aimed at obtaining fibers with high whiteness and well-preserved tenacity.
  • Researchpp 66-81Oh, M., and Tshabalala, M. A. (2007). "Pelletized ponderosa pine bark for adsorption of toxic heavy metals from water," BioRes. 2(1), 66-81.AbstractPDF
    ark flour from ponderosa pine (Pinus ponderosa) was consolidated into pellets using citric acid as cross-linking agent. The pellets were evaluated for removal of toxic heavy metals from synthetic aqueous solutions. When soaked in water, pellets did not leach tannins, and they showed high adsorption capacity for Cu(II), Zn(II), Cd(II), and Ni(II) under both equilibrium and dynamic adsorption conditions. The experimental data for Cd(II) and Zn(II) showed a better fit to the Langmuir than to the Freundlich isotherm. The Cu(II) data best fit the Freundlich isotherm, and the Ni(II) data fitted both Freundlich and Langmuir isotherms equally. According to the Freundlich constant KF, adsorption capacity of pelletized bark for the metal ions in aqueous solution, pH 5.1 ± 0.2, followed the order Cd(II) > Cu(II) > Zn(II) >> Ni(II); according to the Langmuir constant b, adsorption affinity followed the order Cd(II) >> Cu(II) ≈ Zn(II) >> Ni(II). Although data from dynamic column adsorption experiments did not show a good fit to the Thomas kinetic adsorption model, estimates of sorption affinity series of the metal ions on pelletized bark derived from this model were not consistent with the series derived from the Langmuir or Freundlich isotherms and followed the order Cu(II) > Zn(II) ≈ Cd(II) > Ni(II). According to the Thomas kinetic model, the theoretical maximum amounts of metal that can be sorbed on the pelletized bark in a column at influent concentration of ≈10 mg/L and flow rate = 5 mL/min were estimated to be 57, 53, 50, and 27 mg/g for copper, zinc, cadmium, and nickel, respectively. This study demonstrated the potential for converting low-cost bark residues to value-added sorbents using starting materials and chemicals derived from renewable resources. These sorbents can be applied in the removal of toxic heavy metals from waste streams with heavy metal ion concentrations of up to 100 mg/L in the case of Cu(II).
  • Researchpp 82-90Marshall, W. E., Wartelle, L. H., and Akin, D. E. (2007). "Flax shive as a source of activated carbon for metals remediation," BioRes. 2(1), 82-90.AbstractPDF
    Flax shive constitutes about 70% of the flax stem and has limited use. Because shive is a lignocellulosic by-product, it can potentially be pyrolyzed and activated to produce an activated carbon. The objective of this study was to create an activated carbon from flax shive by chemical activation in order to achieve significant binding of selected divalent cations (cadmium, calcium, copper, magnesium, nickel, zinc). Shive carbons activated by exposure to phosphoric acid and com-pressed air showed greater binding of cadmium, copper, nickel or zinc than a sulfuric acid-activated flax shive carbon reported in the literature and a commercial, wood-based carbon. Uptake of calcium from a drinking water sample by the shive carbon was similar to commercial drinking water filters that contained cation exchange resins. Magnesium removal by the shive carbon was greater than a commercial drinking water filtration carbon but less than for filters containing cation exchange resins. The results indicate that chemically activated flax shive carbon shows considerable promise as a component in industrial and residential water filtration systems for removal of divalent cations.
  • Researchpp 91-105Subramanian, R., Fordsmand, H., and Paulapuro, H. (2007). "Precipitated calcium carbonate (PCC) - cellulose composite fillers: Effects of PCC particle structure on the production and properties of uncoated fine paper," BioRes. 2(1), 91-105.AbstractPDF
    This work examines the precipitation of PCC – pulp composite fillers with varying crystal habits and their effects on the papermaking properties of printing and writing paper. Colloidal (c-PCC), rhombohedral (r-PCC), and scalenohedral types (s-PCC) of composite PCCs were produced and compared with commercial reference PCCs. Scanning electron micros-copy showed the c-PCC to be a high-surface-area nano-structured PCC. The rhombohedral composite was formed in clusters like a spider-web structure. Under similar experimental conditions, composite PCC was formed as individual ellipsoidal crystals and some of the particles had malformed structure, in contrast to the structured reference s-PCC. The co-precipitation and the structure of PCC significantly influence the forming, consolidation, and properties of paper, as well as its perform-ance in printing. Composite c-PCC showed the highest retention during forming. At higher filler contents, dewatering was reduced significantly with handsheets containing s- and r-PCC composite fillers. Colloidal composite hand-sheets showed the lowest tensile index and internal bond strength, while the rhombohedral composite gave the highest z-directional bond strength. Compared with the traditional reference samples containing commercial PCCs, paper with s- and r-composites had significantly higher density but similar light scattering ability. Addition of fibrillar fines to fine paper increased print rub fastness significantly in both laser and inkjet printed samples.
  • Reviewpp 106-145Hubbe, M. A. (2007). "Paper's resistance to wetting - A review of internal sizing chemicals and their effects," BioRes. 2(1), 106-145.AbstractPDF
    This review considers research related to internal sizing agents. Such chemicals, when added as emulsions or in micellar form to slurries of cellulosic fibers before paper is made, can make the product resist water and other fluids. Significant progress has been achieved to elucidate the modes of action of alkylketene dimer (AKD), alkenylsuccinic anhydride (ASA), rosin products, and other sizing chemicals. Recent findings generally support a traditional view that efficient hydrophobation requires that the sizing chemicals contain hydrophobic groups, that they are efficiently retained on fiber surfaces during the papermaking process, that they become well distributed on a molecular scale, and that they need to be chemically anchored. A variety of studies have quantified ways in which internal sizing treatments tend to be inefficient, compared to what is theoretically possible. The inefficient nature of chemical and physical processes associated with internal sizing, as well as competing reactions and some interfering or contributing factors, help to explain apparent inconsistencies between the results of some recent studies.