Benjamin E. Dawson-Andoh

Sono-chemical preparation of cellulose nanocrystals from lignocellulose derived materials

This study examined the production of cellulose nanocrystals from microcrystalline wood cellulose, Avicel and recycled pulp of wood pulp using sono-chemical-assisted hydrolysis. Two hydrolysis systems: deionized water and maleic acid were evaluated. In deionized water, Avicel produced cellulose nanocrystals with average diameter of 21+/-5 nm (minimum 15 nm and maximum 32 nm). Cellulose nanocrystals from recycled pulp were not distinctively spherical and had an average diameter of 23+/-4 nm (minimum 14 nm and maximum 32 nm). Maleic acid (50 mM) sono-chemical assisted hydrolysis of Avicel at 15 degrees C and 90% power output for 9 min produced cellulose nanocrystals which were cylindrical in shape and were of dimensions, length 65+/-19 nm and width 15 nm.

Enzymatic-mediated production of cellulose nanocrystals from recycled pulp

Endoglucanase was used to hydrolyze recycled pulp to produce cellulose nanocrystals. The highest yields of cellulose nanocrystals were obtained by treatment with 84 EGU of endoglucanase per 200 mg recycled pulp at 50 °C for 60 min of microwave and conventional heating. Of the two modes of heating investigated, microwave heating at each treatment gave a higher yield than conventional heating. Transmission and scanning electron microscopic analysis of suspensions showed cellulose nanocrystals with widths of 30 nm to 80 nm and lengths of 100 nm to 1.8 μm). This was within range of the length of cellulose crystals (100 nm to 3.5 μm) obtained using dynamic light scattering analysis. The average zeta potential of cellulose nanocrystals was −31.37 mV. X-ray diffraction of cellulose nanocrystals, recycled pulp and residues of recycled pulp shows a gradual change in the particle size.

Rapid characterization of biomass using near infrared spectroscopy coupled with multivariate data analysis: Part 1 yellow-poplar (Liriodendron tulipifera L.).

This paper is the first of a two series papers on the use of near infrared (NIR) coupled with multivariate data analysis (MVDA) as a process analytical technology (PAT) tool for the rapid characterization of physical and chemical properties of two common West Virginian hardwood species, northern red oak (Quercus rubra) and yellow-poplar (Liriodendron tulipifera L.). These two wood species are potential feed stock for the bio-refinery industry. In Part 1, we report our results on yellow-poplar. The results of this study demonstrated that some preprocessing operations on the NIR spectra (first derivative) greatly improved all the prediction models developed in the study. Predictive PLS1 models developed using selective spectra regions, 1300-1800 nm and the full NIR region (800-2400 nm), were similar. The selective spectra region, 1300-1800 nm, included the first and second overtone of the NIR spectrum (1300-1800 nm). Measured and predicted physical and chemical properties of yellow-poplar yielded moderate to high correlation (R2).

Characterization of sugars from model and enzyme-mediated pulp hydrolyzates using high-performance liquid chromatography coupled to evaporative light scattering detection

High-performance liquid chromatography (HPLC) coupled to an evaporative light scattering detector was used to quantitatively determine glucose and cellobiose in hydrolyzates from the production of cellulose nanofillers from modified lignocellulosic materials. Prevail Carbohydrate ES 5 micron column proved more suitable for achieving the chromatographic separation of the model pulp hydrolyzate into its constituent sugars than the YMC-Pack Polyamine column. Linear calibration curves for the various sugars in the mixtures were developed. Glucose and cellobiose were clearly detectable in pulp hydrolyzates obtained from enzyme-mediated hydrolysis of recycled pulp, pine and hardwood dissolving pulps. Finally, the amount of glucose in the pulp hydrolyzates was generally higher than cellobiose.

High density polyethylene-wood flour composite lumber: efficacy of two proprietary biocides in the control of fungal colonization and discoloration

AbstractTwo proprietary biocides were compounded and extruded at three concentrations, respectively, into high density polyethylene-maple wood flour lumber (HDPE-MWL) and evaluated for their efficacy to control fungal colonization and discoloration using the ASTM Standard G 21-96. Although the silver biocide used in this study did not control fungal colonization and discoloration of HDPE-MWL, statistically significant difference was observed between the highest silver biocide concentration and those of the two lower silver biocide concentrations. The latter exhibited no significant difference with the controls. In contrast, the three levels of zinc biocides showed significant difference from each other with respect to their efficacy against fungal colonization and discoloration of HDPE-MWL. Overall, only the zinc biocide was efficacious against fungal colonization and discoloration. The biocide containing zinc as an active biocidal agent was most efficacious at 1% (by weight) concentration. ZusammenfassungZwei praxisübliche Holzschutzmittel wurden jeweils in drei Konzentrationen in einen WPC-Holzwerkstoff eingebracht und hinsichtlich ihrer Wirksamkeit gegenüber Pilzbefall und Verfärbung nach dem ASTM Standard G 21-96 untersucht. Das in dieser Studie verwendete Biozid auf Silberbasis erwies sich insgesamt als nicht wirksam gegenüber Pilzbefall und Verfärbung von HDPE-MWL. Jedoch wurde ein statistisch signifikanter Unterschied zwischen dem Biozid mit der höchsten Konzentration und den beiden niedrigeren Konzentrationen festgestellt. Bei letzteren ergab sich kein signifikanter Unterschied zu den Kontrollproben. Im Gegensatz dazu unterschieden sich die drei Biozide mit den Zinkkonzentrationen hinsichtlich ihrer Wirksamkeit gegen Pilzbefall und Verfärbung von HDPE-MWL signifikant voneinander. Somit ist nur das Zinkbiozid gegen Pilzbefall und Verfärbung wirksam. Am wirksamsten war das Holzschutzmittel mit Zink in einer Konzentration von 1%.

Susceptibility of High-density Polyethylene/wood-flour Composite to Mold Discoloration

Abstract High density polyethylene (HDPE)/wood-flour composites containing either pine or maple flour were evaluated for susceptibility to mold colonization and discoloration using two different ASTM standards: ASTM standards D4445 and G21. Some test specimens were pre-exposed to accelerated ultraviolet weathering and freezethaw cycles and these were air-dried before exposure to molds in either ASTM D4445 or G21. Mold colonization on the surface of exposed samples was visually rated. Wood plastic composites containing either pine or hard maple exhibited greater fungal colonization and discoloration in the ASTM G21 test than the ASTM D4445. Consequently, the ASTM standard G21 was a more sensitive and better test protocol for evaluating the susceptibility of HDPE/wood-flour composite to mold discoloration. It is evident that constant or frequent moisture presence is necessary for the growth and support of mold colonization and discoloration of HDPE/woodflour composite. Pre-conditioning of HDPE/wood-flour composites to accelerated UV weathering or freeze thaw cycles had no discernible effect on susceptibility to mold discoloration. Environmental scanning electron microscopic analysis of the surface of HDPE/wood-flour composite clearly indicated that wood flour is not completely encapsulated by the HDPE matrix and exposed wood flour may serve as points for moisture adsorption and fungal colonization.

Ergosterol content as a measure of biomass of potential biological control fungi in liquid cultures

Gliocladium roseum 784A and G. solani 810A exhibited the highest and lowest levels of ergosterol, respectively, under test conditions. Based upon relative amounts of ergosterol produced per mycelial dry weight, three groups namely high (G. roseum 784A), medium (Mariannaea elegans 386E, G. roseum 321M, G. viride 623E, G. virens 258C and G. virens 258D) and low (Trichoderma pseudokoningii 228B, G. solani 810A) were identified. Concentration of ergosterol do not always correlate with absolute fungal biomass and is influenced by both internal and external factors. Test growth conditions should therefore closely mimic that of anticipated environment. Concentrations of ergosterol of eight biological control fungi reported in this study fall within the range of other fungi reported in the literature. Under control conditions, ergosterol concentration of the eight potential biological control fungi may be used as a relative index of their biomass and their growth in liquid cultures.Gliocladium roseum 784A und G. solani 810A zeigten die höchsten bzw. niedrigsten Gehalte unter den Testbedingungen. Das produzierte Ergosterol wurde auf die Trockenmasse des Mycels bezogen; daraus ergaben sich drei Pilzgruppen, und zwar mit hohem Gehalt (G. roseum 784A), mittlerem Gehalt (Mariannaea elegans 386E, G. roseum 321M, G. viride 623E, G. virens 258C und G. virens 258D) und niedrigem Gehalt (Trichoderma pseudokoningii 228B, G. solani 810A). Die Konzentration an Ergosterol korreliert nicht immer mit der tatsächlichen Biomasse der Pilze und wird durch interne und externe Faktoren beeinflußt. Die Wachstumsbedingungen der Tests sollten daher die vermuteten Umgebungsbedingungen möglichst genau nachahmen. Die hier ermittelten Ergosterolgehalte der acht Pilzstämme liegen im Bereich anderer in der Literatur beschriebener Pilze. Unter Kontrollbedingungen kann der Ergosterolgehalt dieser Pilze als relativer Index der Biomasse und des Wachstums in flüssigen Kulturen benutzt werden.

Inhibitory and compatibility effects of essential oils on sapstain and biological control fungi.

Abstract Three essential oils (Ceylon citronella, Cedarleaf and Geranium) were evaluated for their fungitoxic activity against four major sapstain fungi (Ophiostoma picea, Aureobasium pullulans, Alternaria alternata, Gliocladium viride) and compatibility with one potential biocontrol fungus (Gliocladium roseurri). Sapstain fungi, which belong to deuteromycetes and ascomycetes, generally colonize and discolor the sapwood of softwood and hardwood lumber. Geranium and citronella oils inhibited growth of all fungi at medium (2.5%, volume/volume) and high (5%, volume/volume) concentrations respectively except for O. piceae and G. viride. Cedarleaf oil inhibited O. piceae at all concentrations and A. alternaia at only high concentration. Cedarleaf oil was also partially compatible with the biological control agent, G. roseum. None of the oils evaluated could be characterized as a selective sterilant.

Effect of processing parameters on the quality of red oak flakes

ABSTRACT A lot of volume of red oak (Quercus rubra) is available for use in the manufacture of oriented strand board (OSB) in the Appalachian and Northeast regions of the U.S.A. However, the large amount of fines and low quality of red oak ring-cut flakes produced in industry have restricted their use in commercial OSB products. This study evaluated the effects of log pre-treatment temperature and disc flaker’s knife clearance on the quality of red oak flakes. Experimental results showed that heat treatment was the dominant factor than the flaker’s knife clearance during oak disc-cut flaking. A large amount of high quality oak flakes with acceptable geometry and minimal fines suitable for usage as face furnish on the OSB panel can be produced with a proper log heating treatment before flaking.