Our peer-reviewed sister journal: Lignocellulose (no author payment)
BioResources, Volume 7, Issue 1
NOTE: Each current issue of BioResources continues to build as new articles are approved.
Nonfood lignocellulosic biomass is an ideal substrate for biohydrogen production. By avoiding pretreatment steps (acid, alkali, or enzymatic), there is potential to make the process economical. Utilization of regional untreated lignocellulosic biomass by cellulolytic and fermentative thermophiles in a consolidated mode using a single reactor is one of the ways to achieve economical and sustainable biohydrogen production. Employing these potential microorganisms along with decentralized biohydrogen energy production will lead us towards regional and national independence having a positive influence on the bioenergy sector. PDF
Based on its rich chemistry and broadly available raw material sources, hydroxymethylfurfural (HMF) has become one of the most promising platform compounds for chemicals and biofuels from renewable biomass, and its production has drawn much attention in recent years. However, it is currently still facing significant technical challenges to make it economically feasible in an industrial scale. Use of ionic liquids has provided a potential alternative to address such challenges. Some studies have shown that the use of ionic liquids and suitable catalysts can inhibit side reactions and decrease the formation of by-products, thus improving selectivity and yield during conversion of renewable biomass to HMF. Moreover, the use of ionic liquids also simplifies the HMF production procedures from crude biomass in a one-pot process. PDF
Reducing basis weight could lead to huge savings of forest resources as well as energy consumption and waste treatment in the papermaking process. However, low basis weight paper generally lacks normal strength and stiffness. The lower the basis weight of the paper, the more important is surface sizing. Highly cross-linked cured epoxy resin, due to its epoxy group and phenyl group, has gained such outstanding mechanical properties and dimensional stability that it could be utilized to enhance paper strength and stiffness through surface sizing when incorporated with oxidized starch. In this study, the impacts of sizing volume, fluid temperature, curing agent, and curing system dosage on sizing were investigated. Our results indicated that a rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper, respectively. The formed resin layers strongly support the paper and thus resulted in the improvement of strength and stiffness. PDF
The beta-O-4 bond cleavage of a non-phenolic β-O-4 type dimeric lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)-ethanol (III), was examined in systems using potassium tert-butoxide as a base (0.5 mol/l) and tert-butanol (tBuOH), dimethylsulfoxide, 1,4-dioxane, or tetrahydrofuran as a solvent. The β-O-4 bond of compound III was cleaved in any system at 30°C, and 2-methoxyphenol (II) was liberated. The amount of compound II liberated was close to the quantitative yield on the basis of the amount of compound III that disappeared, except for the treatment in the t-BuOH system. The reaction rate was dependent on what solvent was used. Half-life periods for these systems were roughly about 6.0, 3.0, 0.7, and 0.2h, respectively. It seemed that the rates were very high when the polarity of the solvents was low. Two reaction products generated from the aromatic ring with two methoxyl groups of compound III, 4-acetyl-1,2-dimethoxybenzene and 3,4-dimethoxybenzoic acid, were detected in all the systems. A peculiar reaction product, 1,2-dimethoxybenzene, was detected in a fairly large quantity, only when the latter two solvents with low polarities were applied. PDF
Poplar (Populus alba L.) lumber with a nominal thickness of 7 cm from the Taleghan region in Iran was dried through convective kiln drying and under three different programs of T5–D2 (Forest Product Laboratory proposed program for poplar), T5–D4, and T5–D6 in order to obtain the optimum kiln schedule so as to protect the wood quality at an appropriate level up to final moisture content of 12±2%. Subsequently, the intensities of warps, superficial and internal cracks occurrence, residual stresses, drying rate, and final moisture gradient were measured. Results revealed that due to low warping values, more homogeneous final moisture profile, fewer internal cracks, and absence of superficial cracks in the program T5–D2 compared to the other two (T5–D4 and T5–D6), this program can be recommended as an optimum program for poplar lumber drying at commercial scale from the Taleghan region. On the other hand and from an energy efficiency point of view, in comparison with the mild schedule (T5-D2), the severe schedule (T5-D6) by saving 456 h of drying time, reduced electricity consumption by 6156 KWh and was therefore found to be $ 240.08 more profitable in this trial. PDF
The aim of this work was to examine the influence the lignin component of wood on the photodegradation of high-density polyethylene (HDPE) in wood/HDPE (WPE) composites. The neat HDPE and wood/HDPE composites were prepared using a twin screw extruder followed by an injection moulder. The lignin content was varied from 0 to 29 %wt. of wood by the addition of delignified wood pulp into wood flour. The results suggested that the photodegradation of HDPE in WPE composites was accelerated by the presence of lignin; the chromophoric groups in the lignin enhanced UV adsorption onto the WPE composite surface. The carbonyl and vinyl indices, color, percentage crystallinity, and the melting temperature increased when the lignin contents were increased. The color fading in WPE composites resulted from photobleaching of lignin. In addition, the presence of lignin led to the development ofl cracks in WPE composites, especially at high lignin contents. For the effect of UV weathering time, the carbonyl and vinyl indices, discoloration, and percentage crystallinity increased as a function of UV weathering times, whereas the melting temperature of HDPE in both neat HDPE and WPE composites and water absorption of specimens decreased; the wood index in WPE composites increased during the initial UV weathering times and then decreased at 720 h weathering time. PDF
Encapsulation of methane-producing bacteria was carried out with the objective of enhancing the rate of biogas production. Encapsulation with a one-step liquid-droplet-forming technique was employed for the natural membrane, resulting in spherical capsules with an average diameter and a membrane thickness of 4.3 and 0.2 mm, respectively. The capsules were made from alginate, using chitosan or Ca2+ as counter-ions, together with the addition of carboxymethylcellulose (CMC). A Durapore® membrane (hydrophilic PVDF) with a pore size of 0.1 µm was used for synthetic encapsulating sachets having width and length dimensions 3×3 and 3×6 cm2 for holding the bacteria. During the digesting process, the dissolved substrates penetrated through the capsule membrane, and biogas inside the capsules was able to escape by diffusion. The results indicate encapsulation to be a promising method of digestion, with a high density of anaerobic bacteria. The method holds considerable potential for further development of membranes and their applications. PDF
Reversible thermochromic paper able to resist counterfeiting was prepared by adding reversible thermochromic microcapsules (RTM) to a slurry of cellulosic fibers, a process that is difficult to imitate. However, the loss of RTM is one of the biggest problems that inhibits industrial use of this approach. So, the retention of RTM in pulp was investigated. The RTM was synthesized by in-situ polymerization, and its properties were characterized. It exhibited strong color contrast between cool and heated conditions, and such behavior could be used to achieve distinctive anticounterfeiting characteristics in the paper. The surface of each microcapsule was smooth, and there was no coherence between particles. The diameters of the microcapsules were mainly in the range 3.0 μm to 5.0 μm. Retention of RTM was closely related to beating degree and pulp composition; the higher the beating degree and hardwood pulp content, the higher the retention of RTM. On the other hand, the retention of RTM was influenced by filler and retention aid. Retention aid promoted retention of RTM to some degree; however, filler was not conductive to retention of RTM. Different addition sequences between RTM and filler or retention aid also influenced the retention of RTM. PDF
Cellulose fibers obtained from the textile industry (lyocell) were investigated as a potential reinforcement for thermoset phenolic matrices, to improve their mechanical properties. Textile cotton fibers were also considered. The fibers were characterized in terms of their chemical composition and analyzed using TGA, SEM, and X-ray. The thermoset (non-reinforced) and composites (phenolic matrices reinforced with randomly dispersed fibers) were characterized using TG, DSC, SEM, DMTA, the Izod impact strength test, and water absorption capacity analysis. The composites that were reinforced with lyocell fibers exhibited impact strengths of nearly 240 Jm-1, whereas those reinforced with cotton fibers exhibited impact strengths of up to 773 Jm-1. In addition to the aspect ratio, the higher crystallinity of cotton fibers compared to lyocell likely plays a role in the impact strength of the composite reinforced by the fibers. The SEM images showed that the porosity of the textile fibers allowed good bulk diffusion of the phenolic resin, which, in turn, led to both good adhesion of fiber to matrix and fewer microvoids at the interface. PDF
Chang, X. F., Olson, J. A., and Beatson, R. P. (2012). "A comparison between the effects of ozone and alkaline peroxide treatments on TMP properties and subsequent low consistency refining," BioRes. 7(1), 99-111.
As part of a program to reduce electrical energy consumption in the refining process, the effects of the ozone and alkaline peroxide treatments on fibre and handsheet properties, prior and subsequent to low consistency (LC) refining, were assessed and compared by applying different levels of ozone and a range of peroxide and alkali charges to a primary stage hemlock thermomechanical pulp (TMP). Both highly alkaline peroxide treatments and ozone treatments decreased the specific energy required for strong mechanical pulp. The improvement in pulp strength through alkaline peroxide treatment mainly resulted from pulp surface changes caused by generation of acid groups. The highly alkaline peroxide treatments significantly increased pulp brightness but did not promote the further fibrillation during the subsequent LC refining. On the other hand, ozone treatments provided tensile strength increases, along with small brightness enhancements for the dark hemlock TMP, and increased the tensile gains obtained through LC refining. The effects of ozone treatments on tensile strength before and after LC refining were the result of pulp surface modifications, fibre swelling, and loss of fibre wall integrity due to non-selective chemical attack. High levels of ozone treatment caused tear strength to decrease during subsequent LC refining. PDF
López Rivilli, P., Alarcón, R., Isasmendi, G. L., and Pérez, J. D. (2012). "Stepwise isothermal fast pyrolysis (SIFP). Part II. SIFP of peanut shells - Antifungal properties of phenolic fractions," BioRes. 7(1), 112-117.
Pyrolysis of peanut shells was carried out using stepwise isothermal fast pyrolysis (SIFP). SIFP consists of successive isothermal fast pyrolysis reactions, where solid products obtained in the previous isothermal fast pyrolysis become the substrate of the subsequent reaction at a higher temperature. This article reports results obtained from SIFP of peanut shells between 200 and 300°C using 100°C intervals under vacuum (0.2 mm). The maximum yield of liquid products was obtained at 300°C, giving around 30% of bio-oil, which contained mainly phenols and furan derivatives. On the other hand, since previous papers have reported fungicidal activity of phenols derivatives from lingo-cellulosic biomass pyrolysis, we carried out antifungal activity tests of bio oil obtained from peanut shells SIFT at 300 °C. Results seem promising, at least on Sclerotium rolfsii. PDF
The aim of this work is to chemically characterize olive tree prunings and use the material in hydrothermal and combustion processes. The influence of the hydrothermal treatment conditions, with and without acid catalyst, of the main fraction of olive tree prunings (stems with a diameter > 1 cm) (temperature 150 to 190ºC, time 0 to 20 minutes after reaching the operation temperature, liquid/solid ratio 6 to 8, and sulphuric acid concentration -0.1 to 0.5%), on the composition of resulting liquid fraction and on the solid yield of resulting solid fraction were studied. A polynomial model was found to reproduce the glucose and arabinose concentration, as well as the experimental results for solid yield with errors less than 20% at worst (< 10-12% in 90-95% of all cases). Good content values of glucose (5.33%) and arabinose (2.76%), and an acceptable value of the solid fraction yield (57.96%) were obtained operating with following values of temperature, time, liquid/solid ratio, and sulfuric acid concentration: 186ºC, 18 min, 7:1, and 0.1%, respectively. With these values are saved, with respect to the use of higher values for operating variables, 2.1% energy, 80% sulfuric acid, and more than 10% of capital facilities. Residual fraction of olive tree prunings (leaves and stems with a diameter < 1 cm) had a heating value of 18699 kJ/kg, a flame temperature of 1207-2234 ºC, and a dew point temperature of combustion gasses of 45-53 ºC. PDF
Gao, Y., Zhou, Y., Zhang, X., Zhang, L., and Qu, P. (2012). "Synthesis and characteristics of graft copolymers of poly(butyl acrylate) and cellulose fiber with ultrasonic processing as a material for oil absorption," BioRes. 7(1), 135-147.
A series of materials used for oil absorption based on cellulose fiber grafted with butyl acrylate (BuAc) have been prepared by radical polymerization under ultrasonic waves processing. Effects of ultrasonic dose for the maximum graft yield were considered. The dependency of optimum conditions for oil absorption rate on parameters such as ultrasonic processing time and ultrasonic power were also determined. Fourier infrared (FT-IR) analysis was used to confirm the chemical reaction taking place between cellulose and butyl acrylate. The thermogravimetric behavior of the graft copolymer was characterized by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) analysis was used to determine the surface structure of the grafted material. With the increase of the ultrasonic treatment dose, the surface of the ultrasonic processed material became more regular, and the material was transformed into a homogeneous network polymer having a good structure and good adsorbing ability. PDF
Mihailescu Amalinei, R. L., Miron, A., Volf, I., Paduraru, C., and Tofan, L. (2012). "Investigations on the feasibility of Romanian pine bark wastes conversion into a value-added sorbent for Cu(II) and Zn(II) ions," BioRes. 7(1), 148-160.
The batch sorption capability of Romanian pine bark for the removal of Cu(II) and Zn(II) ions from diluted aqueous solutions was investigated as a function of initial pH, contact time, and temperature. The metal sorption sequence is Cu > Zn. The experimental data for Cu(II) and Zn(II) ions retention on the tested bark of Pinus sylvestris L. showed a better compliance with the pseudo–second order kinetic model. The values of the maximum capacity of sorption, determined on the basis of the Langmuir isotherm model, are 14.7 mg g-1 and 13.01mg g-1 (at 200C) for Cu(II) and Zn(II) ions, respectively. The computed thermodynamic parameters indicate the spontaneous and endothermic nature of Cu(II) and Zn(II) ions sorption process by pine bark. The obtained results suggest that Romanian pine bark is a promising material for the development of a low–cost sorption technology for the removal of Cu(II) and Zn(II) ions from aqueous streams. PDF
The objective of this study was to investigate the bleaching performance of a Mg(OH)2-based hydrogen peroxide process at a high consistency. In this work, an industrially produced chemimechanical pulp (CMP) was bleached via Mg(OH)2- or NaOH-based hydrogen peroxide processes at 10% and 25% consistencies. The results showed that the pulp bleached under the conditions of 1.5% Mg(OH)2 and 3% H2O2 at 25% consistency had a similar brightness to, a lower yellowness index, and a higher opacity than the pulp produced under the conditions of 2.1% NaOH, 3% Na2SiO3, and 3% H2O2 at the same consistency. The temperature (70 ºC) and time (150 min) of the bleaching were the same for both processes. Under the conditions stated above, the Mg(OH)2-based process had a higher yield than the NaOH-based process did. The bleaching effluent of the Mg(OH)2-based process had a higher residual H2O2, but a lower Chemical Oxygen Demand (COD) load and turbidity, compared with that of the NaOH-based process. However, the strength properties and water retention value (WRV) of the pulp bleached via the Mg(OH)2-based process were lower, while its bulk was higher than those of the pulp bleached via the NaOH-based process. PDF
Spent sulphite liquor, the major byproduct from the sulphite pulp production process, was diluted to 50% and used for production of an edible zygomycete Rhizopus sp. The focus was on production, yield, and composition of the fungal biomass composition. The fungus grew well at 20 to 40°C, but 32°C was found to be preferable compared to 20 and 40°C in terms of biomass production and yield (maximum of 0.16 g/g sugars), protein content (0.50-0.60 g/g), alkali-insoluble material (AIM) (ca 0.15 g/g), and glucosamine content (up to 0.30 g/g of AIM). During cultivation in a pilot airlift bioreactor, the yield increased as aeration was raised from 0.15 to 1.0 vvm, indicating a high demand for oxygen. After cultivation at 1.0 vvm for 84 h, high yield and production of biomass (up to 0.34 g/g sugars), protein (0.30-0.50 g/g), lipids (0.02-0.07 g/g), AIM (0.16-0.28 g/g), and glucosamine (0.22-0.32 g/g AIM) were obtained. The fungal biomass produced from spent sulphite liquor is presently being tested as a replacement for fishmeal in feed for fish aquaculture and seems to be a potential source of nutrients and for production of glucosamine. PDF
Inter-clonal and intra-clonal wood properties and their variations from pith to bark were evaluated for wood density and anatomical features on rubber wood (Hevea brasiliensis Muell. Arg) from a 9-year-old plantation with planting densities of 500 and 2000 trees per hectare comprised of clones RRIM 2020 and RRIM 2025. Planting density had uneven effects on wood density and wood cell features. Intra-clonal and inter-clonal variations were significant for wood density in both clones and planting densities. Wood density demonstrated an increasing trend in the radial direction. However, at the lower planting density wood density near the bark decreased slightly. Fiber diameter, lumen diameter, and cell wall thickness showed an increasing trend from pith to bark. Best average fiber characteristics were observed at the lower planting density in clone RRIM 2025. Vessel frequency had a direct relationship with planting density in that it was higher in the higher planting density of 2000 trees per hectare. Overall, planting density had a significant effect on wood quality. The properties of clone RRIM 2025 were found to be comparatively better with longer fiber length and higher wood density than those of RRIM 2020. PDF
Alfalfa stems and ground aspen were exposed to peracetic acid (0.5 to
Pirraglia, A., Gonzalez, R., Saloni, D., Wright, J., and Denig, J. (2012). "Fuel properties and suitability of Eucalyptus benthamii and Eucalyptus macarthurii for torrefied wood and pellets," BioRes. 7(1), 217-235.
Torrefaction is the process of heating a material in the absence of oxygen, a pretreatment that represents a promising option for biofuels. Two eucalyptus species harvested in South Carolina, E. benthamii and E. macarthurii, were processed in a torrefier, and wood pellets were manufactured. Eucalyptus represents a promising biomass source in southern U.S. due to fast growth rates and the availability of cold-tolerant plantations. Analyses of moisture content, proximate and elemental composition, and net heating value of “light roasted” wood were assessed. The heating value of the eucalypts and pellets was enhanced by 19% (average), compared to the original material, while the moisture and volatiles content were drastically reduced. This reduction leads to an increase in the amount (w/w) of carbon, enhancing the energy content in the material. Thus, torrefaction is useful for improving the heating value of woody biomass, consuming little external energy due to recirculation and burning of gases for the process. The pellets showed increased energy density, providing improved properties for transportation and handling. PDF
Ogawa, M., Bardant, T. B., Sasaki, Y., Tamai, Y., Tokura, S., and Uraki, Y. (2012). "Electricity-free production of activated carbon from biomass in Borneo to improve water quality," BioRes. 7(1), 236-245.
Activated carbons (ACs) were prepared from biomass of Borneo island (wood charcoal, peat, and coconut husk) by using an electricity–free furnace, of which the energy source was exclusively wood charcoal. This furnace was comprised of two parts, an inner vessel equipped with water inlet for steam activation and an outer shell as a heating part for the inner vessel. The inside temperature of the inner vessel was able to reach over 1000 oC. Peat and wood charcoal were converted to AC by carbonization followed by steam activation, and the specific BET surface areas of resultant ACs were 889 m2/g and 749 m2/g, respectively. A mobile apparatus for water purification was newly designed and fabricated with the resultant AC, together with a white quartz sand, which is called keranggas in Kalimantan. The CODOH of both polluted creek water by the University of Palangka Raya and Kahayan River water were remarkably decreased by the purification with the designed apparatus from 20.0 mgO/L to 0.93 mgO/L, and 18.2 mgO/L to 0.74 mgO/L, respectively. Thus, the newly designed furnace and purification apparatus were shown to be highly effective tools to produce a promising agent for water purification and to produce clarified water without use of electricity, respectively. PDF
Arami-Niya, A., Abnisa, F., Shafeeyan, M. S., Wan Daud, W. M. A., and Sahu, J. N. (2012). "Optimization of synthesis and characterization of palm shell-based bio-char as a by-product of bio-oil production process," BioRes. 7(1), 246-264.
In this study the optimum preparation conditions of bio-char were achieved as a by-product of the bio-oil production process from oil palm shell as an agricultural waste material. To investigate the possibility of utilizing bio-char as an adsorbent for wastewater treatment and other applications, a central composite design was applied to investigate the influence of carbonization temperatures, nitrogen flow rates, particle sizes of precursor, and duration on the bio-char yield and methylene blue adsorption capacity as the responses. Methylene blue was chosen in this study due to its wide application and known strong adsorption onto solids. Two quadratic models were developed for the responses and to calculate the optimum operating variables providing a compromise between yield and adsorption. From the analysis of variance, temperature was identified as the most influential factor on each experimental design response. The predicted yield and adsorption capacity was found to agree satisfactorily with the experimental values. A temperature of 400°C, nitrogen flow of 2.6 L/min, particle size of 1.7 mm and time of 61.42 min were found as the optimum preparation conditions and near to the optimal bio-oil production variables. PDF
Alkaline peroxide mechanical pulping of paulownia wood harvested from exotic tree plantations in northern Iran was investigated. The fiber length, width, and cell wall thickness of this wood were measured as 0.82 mm, 40.3 μm, and 7.1 μm, respectively. The chemical composition including cellulose, lignin, and extractives soluble in ethanol-acetone, 1% NaOH, hot and cold water was determined as 49.5%, 25%, 12.1%, 26.9%, 11.4%, and 8.1% respectively. The ash content of this wood was 0.45%. Pre-washed chips were chemically treated at 70°C for 120 minutes with different combinations of three dosages (1.5, 3, and 4.5%) of hydrogen peroxide and three dosages (1.5, 3, and 4.5%) of sodium hydroxide prior to defibration. Other chemicals including DTPA, sodium silicate, and MgSO4 were constant at 0.5%, 3%, and 0.5%, respectively. The results showed that using a 1.5% hydrogen peroxide and 4.5% sodium hydroxide charge, the brightness of APMP pulp reached 68.7% ISO and higher chemical dosages did not improve the brightness; however, to produce APMP pulp with higher strength, a sodium hydroxide charge of 4.5% was needed. The tensile strength, tear strength, burst strength indices, and bulk density of the APMP pulp produced from 1.5% hydrogen peroxide and 4.5% sodium hydroxide were measured as 15.5Nm/g, 6.54mN.m2/g, 0.56kPa.m2/g, and 3.47cm3/g, respectively. The resulting pulp was bulky and is suitable for use in the middle layer of boxboard to provide the desired stiffness with a lower basis weight. PDF
The OQP, OQPO, and OLQP bleaching sequences have been applied to oil palm frond soda-anthraquinone pulp. Oxygen delignification resulted in a delignification of approximately half of the kappa number. In comparison between OQP and OQPO sequences, the OQPO sequence was able to improve brightness from 75.2% ISO to 82.3% ISO. A TCF bleaching sequence involving laccase was also suitable for the frond pulp bleaching. Results indicated that laccase has a good bleaching capability. Short beating in a PFI refiner (about PFI 2000 revolutions) was sufficient to attain good pulp strength of TCF bleached pulp. There was no total organically bound chlorine in the TCF bleaching effluent. The results of this study show that soda-anthraquinone pulping and TCF bleaching is a promising alternative to produce high-quality pulp from oil palm frond for writing and printing paper. PDF
Feria, M. J., García, J. C., Pérez, A., Gomide, J. L., Colodette, J. L., and López, F. (2012). "Process optimization in kraft pulping, bleaching, and beating of Leucaena diversifolia," BioRes. 7(1), 283-297.
A variety of the Leucaena genus, Leucaena diversifolia, was used for pulp and paper making by kraft and refining processes and a OD(EP)DP bleaching sequence. The same species has been suggested as an energy crop and, in fact, this species used shows a high gross heating value; besides, this variety of Leucaena has appropriate characteristics for pulp and paper making. The holocellulose content was higher than Eucalyptus globulus, and ash and lignin contents were comparable to other varieties of Leucaena. Pulps with a kappa number between 17 and 18, and 21.4 cP viscosity were obtained using an active alkali concentration of 31%. Also, paper sheets showed good strength properties, comparable or even greater than those obtained with Eucalyptus or others varieties of Leucaena at comparable refining degrees, between 30 and 40 ºSR. The pulp was successfully bleached in all cases with a kappa number below 1.5 in the EP stage and a value of brightness higher than 90%. PDF
The potential of spherical lignin beads as an adsorbent to take up L-lysine from aqueous solution was investigated. The kinetic data were estimated by the pseudo-first-order and pseudo-second-order models. The mechanism of adsorption was also studied using the Boyd model and Webber’s intraparticle diffusion model. The equilibrium data were modeled by the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms as well. Results suggested that the adsorption kinetics can be best described by the pseudo-first-order model. The adsorption process initially was controlled by film diffusion, whereas the subsequent stage was controlled by intraparticle diffusion. The equilibrium data could be well fitted using the Langmuir isotherm model with a maximum adsorption capacity of 67.11 mg·g-1. The adsorption characteristics of the spherical lignin adsorbent proved the feasibility of its use as an alternative adsorbent for the removal of L-lysine from aqueous solution. PDF
Fluorescent whitening agents (FWAs) are the most widely used functional chemicals for the manufacture of printing and writing grades of paper. FWAs are used as internal or external additives for the surface treatment on the size press and coater. In spite of the extensive use of FWAs, no method has been established to analyze the FWA content in process water and paper products. Samples are typically exposed to UV light in order to detect the presence of FWAs. This method is based on the fluorescence exhibited by FWAs under a UV-lamp. The observation of fluorescence with the naked eye is highly subjective. Thus, it is essential to develop a more scientific and objective to the quantitative analysis of FWA optical effects. Water and paper samples containing FWAs were prepared in a laboratory. Quantitative analysis was carried out with a spectrofluorometer, a spectrophotometer, and an image restoration microscope. Using these analytical instruments, fluorescence was observed. Regression equations were obtained from the relationship between the fluorescence intensity and the FWA optical effects of the samples. PDF
Quintanar Gómez, S., Arana-Cuenca, A., Mercado Flores, Y., Gracida Rodríguez, J. N., and Téllez-Jurado, A. (2012). "Effect of particle size and aeration on the biological delignification of corn straw using Trametes sp. 44," BioRes. 7(1), 327-344.
Straw is an agricultural byproduct that can be utilized to obtain bioethanol without affecting animal or human sustinence. This process involves recovering the sugars and reducing the lignin content present through the use of ligninolytic fungi such as the basidiomycete Trametes sp. 44. Fermentation was carried out using particle sizes 4 (4.76 mm, No. 4 sieve) and 8 (2.30 mm, No. 8 sieve), and two velocities of airflow (100 and 200 mL/min). Study results showed that particle size affected the production of hydrolytic enzymes, as particle size 8 favored the expression of cellulases and hemicellulases. In addition, both aeration and particle size affected the expression of ligninolytic enzymes, as it was observed that with particle size 8 and airflow of 200 mL/min, the study detected 63 AU/mL of LiP and 11 AU/mL of MnP. In the case of laccase, the enzymatic activity detected reached 220 AU/mL using particle size 8 and an airflow velocity of 200 mL/min. Statistical analysis indicated that the treatment that produced the highest biological delignification occurred when Trametes sp. 44 was grown on corn straw at particle size 4 and airflow of 100 mL/min, conditions that yielded 34% delignification at day 12 of fermentation. PDF
Two agricultural biomass materials, namely wheat straw and sugarcane bagasse, were pretreated with NaOH and then used as substrates for enzymatic saccharification. After the pretreatment, the increase in glucan content and the decrease in lignin content were more than 65%, while less than 20% increase occurred in xylan content. The enzymatic saccharification was initiated with solid loading 9% (w/v), and then 8%, 7% and 6% (w/v) solid was fed at 8, 24, and 48 h, respectively. The final enzyme solid loading was 9.60 FPU/g solid and 30% (w/v), respectively. At 144 h, the produced glucose, xylose, and reducing sugar concentrations for wheat straw were 81.88, 20.30, and 115.25 g/L, respectively, and for sugarcane bagasse they were 125.97, 8.66, and 169.50 g/L, respectively. The final conversions of wheat straw and sugarcane bagasse were 34.57% and 50.85%, respectively. SEM images showed that the surface structure of the two materials changed a lot via alkali-pretreatment and enzymatic hydrolysis. In summary, a high concentration sugar is produced from the two agricultural biomass materials by high solid and low enzyme loading. Compared to wheat straw, sugarcane bagasse is more suitable for use in sugar production. PDF
Three commercial starches were evaluated in conjunction with colloidal silica and flocculant to retain precipitated calcium carbonate (PCC) filler. A unique feature of this study was the fact that the filler was pre-flocculated by a portion of starch (2kg starch/t PCC) and the rest of the starch was added after the flocculant but before the silica. The pulp used was peroxide bleached thermo-mechanical pulp (TMP). A statistical design methodology was employed and empirical process models were constructed based on the analysis of variance (ANOVA) results. The models were then employed to predict the retention and drainage. It was found that the high-charged cationic starch gave the highest retention and best drainage performance. The high-charged cationic starch S880 also resulted in stronger paper, probably because of the larger and stronger flocs produced and its higher affinity with the fiber and fines. Finally, pre-flocculation was found to provide stronger paper compared with a conventional starch/retention aid addition sequence. PDF
Peng, H., Hu, Z., Yu, Z., Zhang, J., Liu, Y., Wan, Y., and Ruan, R. (2012). "Fractionation and thermal characterization of hemicelluloses from bamboo (Phyllostachys pubescens Mazel) culm," BioRes. 7(1), 374-390.
Water-soluble hemicelluloses and eight alkali-soluble hemicelluloses were fractionated from bamboo (Phyllostachys pubescens Mazel) culm with hot distilled water, 2% NaOH, 2% KOH, 5% NaOH, and 5% KOH aqueous solution. The chemical structures, as analyzed employing FTIR spectrometry, suggested that all the hemicelluloses were likely to be comprised of arabinoxylans associated with lignin more or less. Thermal analysis for hemicelluloses was carried out using TG-DTG method under nitrogen atmosphere at a heating rate of 10 °C/min, and first-order kinetics was evaluated. The major pyrolysis was focused at 187-346 °C, with activation energy ranging from 23.77 to 45.02 kJ/mol. The alkali-soluble fractions, being soluble in solution only at pH higher than 5.5, presented lower thermal stability and higher values of activation energy and pre-exponential factor than the alkali-soluble fractions remaining soluble in alkaline solution at pH lower than 5.5 and insoluble in ethanol. The chemical property of the hemicellulose fractions may greatly influence the thermal characteristics. PDF
Janga, K. K., Hägg, M.-B., and Moe, S. T. (2012). "Influence of acid concentration, temperature, and time on decrystallization in two-stage concentrated sulfuric acid hydrolysis of pinewood and aspenwood: A statistical approach," BioRes. 7(1), 391-411.
The effects on sugar yields of acid concentration, temperature, and time in the first (decrystallization) stage of a two-stage concentrated sulfuric acid hydrolysis of softwood (Scots pine) and hardwood (aspen) were investigated. The study focused on the multi-variable effects of the decrystallization stage and applied a statistical modeling with Central Composite Face (CCF) design of experiment to systematically study and simulate the effect of decrystallization reaction conditions on hydrolysis products and degradation products. The models were statistically significant and showed that for both aspen and pine, the reaction temperature and acid concentration were the most influential variables on monosaccharides and total sugar yields compared to the reaction time. The interaction between temperature and acid concentration was the most important for both species. The sugar degradation products were much influenced by the decrystallization temperature on both aspen and pine. The models were validated by a test-set and showed a good agreement between the experimental and predicted values. The optimum predicted total sugar yields were 56 g / 100 g d.w for aspen (74% theoretical) and 64 g / 100 g d.w for pine (91% theoretical). PDF
Paulownia Tomentosa was pretreated by steam explosion. The cellulase complex NS 50013 and the β-glucosidase NS 50010 of Novozymes AS were used for the enzymatic conversion of cellulose to glucose. The kinetics of enzyme conversion was studied using the exponential kinetic equation valid for processes taking place at uniformly inhomogeneous surfaces. The kinetic coefficient of inhomogeneity accounts for the energy and entropy inhomogeneity of the system and depends on the temperature. It was established that both the activation energy and the pre-exponential factor increase simultaneously with increasing of conversion degree. A compensation effect between pre-exponential factor and activation energy was observed. The energetic hindrances established cannot be completely compensated by the positive effect of the pre-exponential factor increase. Hence, the activation energy has a determining influence on how quickly the rate of hydrolysis decreases. PDF
In this study three different ways of applying ultrasound for the production of nanocellulose from native cellulose were explored. In the first option bleached hardwood kraft pulp was oxidized with the ultrasound (US) assisted TEMPO/NaBr/NaOCl-system (US-TEMPO-system) followed by mechanical separation of nanocellulose. The pulp oxidized by the US-TEMPO-system had higher carboxyls content and ca. 10% increase in nanocellulose yield when compared to the TEMPO-system without sono catalysis. In the second option ultrasound pretreated pulp was oxidized using the TEMPO-system. Although there was no gain in carboxyls content in this process versus the oxidation with TEMPO-system without ultrasound treatment, a higher degree of fibrillation was obtained after ultrasound treatment. In the third case the TEMPO oxidized pulp was subjected to mechanical and ultrasound treatments for nanocellulose production. Under similar treatment time the subsequent ultrasound treatment achieved higher nanocellulose yield than the subsequent mechanical treatment. However, in comparison, the ultrasound treated nanocellulose had lower Rheometer Stresstech viscosity. Furthermore, it was observed that cellulose nanofibrils produced by ultrasound treatment were slightly thinner compared to those produced using the mechanical method. PDF
The objective of this study was to determine the effects of some boron compounds, which have fire retardant properties, as well as melamine-urea-formaldehyde (MUF) resins having different melamine contents (10%, 15%, and 20%) on some physical and mechanical properties of medium density fiberboard (MDF) panels. It was found that the water absorption (WA) and thickness swelling (TS) of MDF panels increased depending on types and concentrations of boron compounds. However, the WA and TS values of MDF panels decreased with increasing melamine content in MUF resins. It was also found that the modulus of rupture (MOR) and internal bond strength (IB) of MDF panels showed different trends depending on the experimental parameters. Boron compounds showed some negative effects on the MOR and IB values. However, these effects decreased with increasing melamine content in MUF resins. The best results were obtained in MDF panels manufactured with an MUF resin having 20% melamine content. Consequently, increasing melamine content in MUF resins showed positive effects on some properties of MDF panels. PDF
Liu, C., Yang, X., Cui, J., Zhou, Y., Hu, L., Zhang, M., and Liu, H. (2012). "Tung oil based monomer for thermosetting polymers: Synthesis, characterization, and copolymerization with styrene," BioRes. 7(1), 447-463.
A tung oil (TO) based monomer for rigid thermosetting polymer was synthesized, characterized, and copolymerized with styrene in this study. Tung oil was alcoholyzed with pentaerythritol (PER) to get tung oil pentaerythritol alcoholysis products (TOPER), and the optimized conditions were explored according to the yields of TOPER analyzed by gas chromatography-mass spectrometry (GC-MS). The resulting alcoholysis products were maleinated to form tung oil maleate half ester (TOPERMA), and the reaction conditions were determined by monitoring the reaction extents of TOPER and maleic anhydride (MA) with 1HNMR spectroscopy. The TO alcoholysis and maleinization reaction products were characterized by IR, 1HNMR, and electrospray ionization-mass spectrometry (ESI-MS) techniques. At last, the TOPERMA mixture was cured with styrene (St), and the initiator tert-butyl peroxy benzoate (TPB). Differential scanning calorimetry (DSC) was employed to characterize the curing process. Mechanical properties of the cured TOPERMA/St resin further confirmed the best procedure for the maleinization reaction. The loading of TO reached about 30% weight of the resulting thermosetting polymer. This promising material from renewable resources can be a potential substitution for petroleum products when used as sheet molding compounds. PDF
Guisado, G., López, M. J., Vargas-García, M. C., Suárez-Estrella, F., and Moreno, J. (2012). "Pseudallescheria angusta, a ligninolytic microorganism for wood fibres biomodification," BioRes. 7(1), 464-474.
Nowadays, the discovery of lignocellulolytic microorganisms that are better adapted to operational conditions while exhibiting the strong degrading activities is highly desired for successful lignocellulose biotransformation processes. In this study, microorganisms were isolated from lignocellulose-rich composting materials by selective methods. A screening of isolates known to have lignocellulolytic abilities was performed using several tests. Seven microorganisms showed ligninolytic potential and were subjected for further analysis according to their degrading activity. The fungus Pseudallescheriaangusta MF4 demonstrated high decolorization rates for three aromatic dyes: Poly R-478, Poly S-119, and Remazol Brilliant Blue R. In addition, the fungus showed a high production rate of ligninolytic enzymes in the presence of inducers. This fungus achieved the highest values of growth after 21 days of incubation on sawdust without any additional nutrients. Owing to its proven ligninolytic activity and capability of growing on a lignocellulosic substrate, the application of this isolate could be of interest in different biotechnological applications, particularly in biological treatment of wood fibres in order to improve the production of wood-based composites. PDF
The potential use of kapok fiber for pulping and papermaking has been investigated. The kapok fibers were cooked using the optimal dosage of sodium hydroxide determined from the experiments. Then, the pulp was refined with two passes using a disc refiner and mixed with commercial hardwood pulp and/or softwood pulp at different blend ratios to make papers. It was found that addition of the kapok pulp to the mixed pulps improved the tensile and burst strengths of the sheets but decreased the tear resistance and elongation. Water repellency of the sheets prepared from the kapok pulp mixed with the commercial pulps was also improved. These results indicate that kapok fiber can be a quality pulp source for papermaking, especially for packaging paper requiring strength and water repellency. PDF
This research provides an optimal design of structural parameters for ring-die granulators used in the cool briquetting process. Experimental research on the briquetting rate of pellets was carried out for three kinds of crop straws with different granularities, moisture ratios, and length-diameter ratios of the die hole. Results showed that: when the swoop angle β was 45o and the diameter ratio of roller to die was equal to 0.585, the equipment would have higher productivity and lower die-roller contact strength, yielding a good comprehensive briquetting effect; when the granularity was 4mm, the moisture ratio was 16% and the length-diameter ratio was 5.2, the equipment would ensure a higher briquetting rate of pellets and the lowest power consumption per ton of material, yielding the best briquetting effect. This provides references for structural design and process parameters selection of ring-die granulators. PDF
This study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA). Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S), water uptake capacity (D), anti-swelling efficiency (ASE), and water repellent efficiency (WRE) after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term. PDF
The organization of the major polymers in the wood fiber has a large impact on the properties of the structure. Numerous studies have been devoted to the cellulose microfibril arrangement, providing the longitudinal strength of the fiber, while less is known regarding the structural organization of other components, such as hemicelluloses and lignin. For the hemicelluloses, as being part of the cellulose aggregation process, indications of a strong coupling to the cellulose structure have been shown. For lignin, being laid down in a later stage, no clear picture has emerged. Here the orientation of lignin vis-à-vis the cellulose orientation was examined for a number of different fiber structures. It was shown that the lignin in the middle lamella region seems to be non-oriented, thus more resembling an isotropic material, while the lignin in the secondary wall is to some extent oriented. The orientation of this lignin is less pronounced than the orientation of cellulose but has a preferential alignment in the direction of the fiber axis. The reason for this alignment could be related to structural restrictions of this lignin, deposited in the spaces remaining after the initial forming of the structured cellulose/hemicellulose fibrillar structure. PDF
Fructose can be efficiently converted to 5-hydroxymethylfurfural by using the functionalized ionic liquid 3-(2-chloroethyl)-1-methylimidazolium chloride as both solvent and catalyst in the presence of water. This work advances the field and is distinct from earlier efforts in the sense that the observed yields of HMF from fructose are rather high and the reaction conditions rather mild and neutral in the complete absence of acidic additives (HMF yield 76% at 100 oC in 40 minutes). PDF
A novel process involving a paper-based ultrafiltration (UF) membrane was developed via paper coating technology. The membrane employed a paper sheet as support layer and a coated thin film layer of adhesive. The proper selection of paper sheet support layer was crucial to the performance of the ultrafiltration membrane. A paper sheet with beating degree of 85oSR and basis weight of 50g/m2 was chosen as the support. PVA was chosen as the adhesive. The paper-based ultrafiltration membrane achieved high retention performance while using a simple production process and keeping the production cost low. Disadvantages of the membrane included low porosity and low pure water flux. So further investigation is still needed to produce a fully satisfactory paper-based ultrafiltration membrane. PDF
Phenolated lignosulfonate was introduced into the synthesis of phenolic resol with phenol and formaldehyde in an alkaline condition. The modified resol was successfully applied to prepare phenolic foam using appropriate combinations of flowing agents. N-pentane was found to be suitable as the foaming agent. Sulphuric acid (50% aqueous solution, w/w) and Tween-80 were used as catalyst and surfactant, respectively. The obtained foams were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), friability, and mechanical property tests. The experimental results showed the foam to have lower density, better toughness, and excellent thermal insulation compared to those of foams obtained from conventional resol resin. The properties of phenolated lignosulfonate modified phenolic foam can comply with the required specifications for its practical utilization. PDF
In this study it was aimed to improve impregnability of spruce (Picea orientalis L.) wood with bacteria (Bacillus licheniformis A1) pretreatment, using copper/chromium/arsenic Type C (CCA-C) andcopper azole Type A (CBA-A). The effects of Bacillus licheniformis A1 on weight loss, copper uptake, and compression strength of samples were determined. Weight loss was slightly changed by bacterial degradation in all test groups. The best copper uptake cases were 1466 ppm for CCA-C and 2730 ppm for CBA-A. Improvement on copper uptake with bacteria pretreatment was in a range of 18 to 103% compared to control samples. Compression strength was decreased by bacterial degradation. However strength losses might be acceptable for several construction applications. Bacillus licheniformis A1seems to havea good potential for increasing the permeability of spruce wood. PDF
Kang, N., Liu, Z., Hui, L.-F., Si, C.-L., Cui, L., Zhao, T., and Mao, S.-T. (2012). "Study on the optimum process of acid-catalytic ethanol pretreatment of Chinese triploid poplar to enhance sugar recovery by hydrolysis," BioRes. 7(1), 578-592.
Organosolv pretreatment was applied to Chinese triploid poplar using the acid-catalysis ethanol method to enhance sugar recovery in enzymatic hydrolysis. A Box-Behnken design (BBD) was used to optimize the effect of temperature, ratio of wood to liquor, ethanol concentration, and holding time on the pretreatment process. All variables except for lignin content were found to significantly affect the cellulosic yield as well as crystallinity index (CrI). Quadratic polynomial equations were used to model on the cellulosic yield, CrI, and lignin content for a regression analysis, using response surface methodology (RSM). The optimum process of organosolv pretreatment of Chinese triploid poplar was found to be: temperature: 185 ºC, ratio of wood to liquor: 1 to 4.2, ethanol concentration: 45%, and holding time: 41 min. The solid pretreated under optimum process conditions was evaluated for bioconversion using enzymatic hydrolysis of the cellulose fraction to glucose. Approximately 87% of the total cellulose in the poplar was recovered as monomeric glucose after hydrolysis of the solid fraction. PDF
Fire retardant particles (guanylurea phosphate and boric acid) with a morphological characteristic of large crystal or fine microsphere, were respectively applied to wood fibers to make medium density fiberboard (MDF). The effects of particle size of the fire retardant on the combustion performance of the resulting MDF samples were determined using a thermogravimetric (TG) analyzer and cone calorimeter (CONE). The scanning electron microscopy and laser particle size analysis showed that the microspheric particles of fire retardant had a mean size of approximately 20 µm, which was smaller than the crystal (260 um). Incorporation of the fire retardant either in the crystal or microsphere shape reduced the weight loss of the resulting MDF, as evidenced by the TG analysis and the CONE test; the release rate and total amount of both the heat and smoke were apparently inhibited as compared to the untreated MDF samples. Treatments caused an increase in both the ignition time and charring ratio of the MDF. Compared with the fire retardant crystals, the fine microspheric particles exhibited greater ability in inhibiting the release of heat and smoke through the combustion processes. PDF
Enzymes still exhibit activities after hydrolysis of biomass according to previous studies. Recycling the enzymes and use them in subsequent hydrolysis cycles can further utilize their remaining activities. Previous studies have mainly discussed enzyme recycling processes up to three cycles, in which the processes did not reach steady state. Steady state investigation is essential for the guidance of the real life process. Four cycles of processing have usually been considered enough to bring the system to steady state in process engineering. In this work, hydrolysate was used as the source of recycled enzymes to fresh substrate for five cycles. Because a large amount of enzymes remained on the pulp, surfactant was introduced to recycle the enzymes that remained with the residue. Recycled hydrolysate from previous enzymatic hydrolysis usually carries a high concentration of sugars, which can inhibit the new round of hydrolysis. To remove sugar from the recycling stream, a wash with fresh buffer was performed. Sugars were removed, while enzymes still remain on the fresh substrates. Six recycling strategies were evaluated for enzyme recycling percentage and enzymatic hydrolysis efficiency with both green-liquor pretreated softwood and hardwood in this investigation. Hydrolysis efficiency increased by about 40% for softwood at 30 mg/g enzyme dosage and about 25% for hardwood at 7.5 mg/g when a washing stage was applied with addition of surfactant. PDF
Zhang, H., Song, S., Lang, Q., Zhang, J., and Pu, J. (2012). "Rapid predictive models for minimally destructive Kappa number and pulp yield of Acacia spp. with near infrared reflectance (NIR) spectroscopy," BioRes. 7(1), 616-623.
Kraft pulp and wood powder from Acacia Spp. were selected for the development of rapid, minimally-destructive, and environmentally friendly predictions of kappa number and pulp yield, by means of near infrared reflectance (NIR) spectra. The models, based on Partial Least Squares Regression (PLS-R), were established with fifty-four calibration samples selected by Principle Component Analysis (PCA), while the validation models resulted from nineteen samples that were not included in the calibration set. The accuracy and stability of calibration models were evaluated by coefficient of determination for calibration (R2cal) and root mean square error of cross-validation (RMSECV). The coefficient of determination for validation (R2val) and root mean square error of prediction (RMSEP) were used for validation models. The main results showed that: (1) the predictive models from pulp were more credible in terms of the R2cal and R2val values than those from wood powder by 25 to 70%; and (2) a validation model for kappa number from pulp showed a better stability than the corresponding calibration model, since RMSEP was 23.5% less than RMSECV, while calibration models for pulp yield were more steady than validation models. This study provided reliable models for predicting kappa number and pulp yield rapidly and with a minimal need for physical sampling. PDF
Flax shive (FS) is a byproduct from flax fiber separation. The use of absorbent prepared from chitosan-modified flax shive (CFS) has been studied for removal of reactive red dye (RR228) from aqueous solutions. CFS was characterized by the Brunauer-Emmett-Teller (BET) method, Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectrometry (FTIR), and X-ray photoelectron spectroscopy (XPS). A batch adsorption study was conducted under various contact time, initial concentration, solution pH, and adsorbent dosage. It was found that the BET and Langmuir surface area of CFS were 1.772 m2 g-1 and 3.057 m2 g-1, respectively. Results showed that CFS has the same pores as FS and that the –NH2 group on CFS is the main adsorption site for dye sorption. Equilibrium adsorption capacity could be reached within 480 min, and RR228 uptake was satisfactory at a pH of 2.0. The percentage removal were 100%, 100%, 90%, and 85% at pH 2.0 under dye concentrations of 10 mg/L, 20 mg/L, 30 mg/L, and 40 mg/L, respectively. The adsorption accurately fitted a pseudo-second-order kinetic model and a Langmuir isotherm model. It is proposed that CFS could be applied as a low-cost absorbent in removal of dyes from wastewater. PDF
Commercial bamboo chips were evaluated as raw material for dissolving pulp production. The chips were auto-hydrolyzed (AH) and subsequently cooked by the NaOH/AQ process and bleached to full brightness with the O-CCE-D-(EP)-D-P sequence. The term CCE designates a cold caustic extraction stage. The bamboo chip chemistry (22.4% lignin, 19.5% xylans, 49.3% cellulose, 16.8% total extractives, and 1.5% ash) was apparently unfavorable; however high quality dissolving pulp was produced using the aforementioned technologies, even when compared to results obtained with traditional eucalypt commercial wood chips. The pulp showed high brightness (92.4 % ISO) and α-cellulose content (94.9%). Its contents of hemicelluloses, extractives and ash were within acceptable levels for a dissolving pulp aimed at viscose rayon production. Thus, the bamboo chip furnish investigated can be regarded as a viable raw material for dissolving pulp production. PDF
A cellulose homogeneous system was prepared by dissolving cellulose fibre in an 8.0 wt% LiCl/DMAc solution. AKD was reacted with the cellulose under the homogeneous system and a heterogeneous system, respectively. The reaction products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Wide-angle X-ray diffraction (WXRD). The results indicated that hydrogen bonds between cellulose molecules were disrupted under homogeneous conditions. The activity and accessibility to the reagent of hydroxyl groups were enhanced so that the β-keto ester bonds between AKD and cellulose were generated. However, the activity and accessibility of hydroxyl protons of the anhydroglucose units were not highly reactive under heterogeneous conditions. Moreover, cellulose itself was heterogeneous in nature, as different parts of its constituent fibrils displayed very hard accessibilities to the reagent. The β-keto ester bonds were not detected in the reaction products. Thus, the reaction between AKD and cellulose was difficult to achieve under heterogeneous conditions. In the sizing process, the reaction of cellulose should not simply be regarded as being that of a trihydric alcohol that is similar in its chemistry to sugars having three hydroxyl groups. Thus, the controversy about the sizing mechanism of AKD still remains unresolved. PDF
The tensile strength and bending strength of natural coir fiber are lower than many other natural fibers. Therefore, coir fiber is unsuitable for many fiber reinforcement applications. This study exploits the better shock resistance and toughness of coir fiber, which suggest that coir fiber can be used as a type of replacement material in plywood. Fast-growing poplar was chosen as the surface material, and coir fiber was selected as the core layer material for their buffering ability and toughness, and fiberglass fabrics were added in the core layer as strengthening components. The optimization of this plywood structure was carried out with an orthogonal experiment and the intuitive analysis method. The mechanical performance of some samples even exceeded that of natural wood. Through analysis of test results and scanning electron microscope (SEM) observations, the buffering and toughening mechanisms of the coir fiber mats were revealed. This new material can be used to replace wood in plywood and in the transportation industry as a packaging material and as platform floors for freight vehicles. PDF
Li, H., Lu, J., and Mo, J. (2012). "Physiochemical lignocellulose modification by the Formosan subterranean termite Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) and its potential uses in the production of biofuels," BioRes. 7(1), 675-685.
Formosan subterranean termites (Coptotermes formosanus Shiraki) and other wood-feeding insects have the ability to digest cellulose and structurally modify or degrade lignin. We examined the physical and chemical changes to lignocellulosic components of Chinese red pine (Pinus massoniana) after passing through the termite (C. formosanus) digestive system. The purpose of this research was to evaluate biochemical digestive processes in the C. formosanus gut as potential models for biofuels processing. Results suggest that demethylation, demethoxylation, and propyl side-chain modification are responsible for higher lignin removal and cellulose crystallinity reduction after structural alteration. SEM images also further indicated that unlike the fungus- growing termites Odontotermes formosanus, the lower termites C. formosanus disrupted the lignocellulose structure, and thus resulted in an increase of surface area to cellulase. Comparative enzymatic hydrolysis tests between raw wood and C. formosanus faeces revealed an enhanced level of enzymatic digestibility in digested material. Based on the results, C. formosanus can efficiently modify lignin at ambient temperatures and pressures in contrast to current methods used in biofuels production. PDF
Fifty-three algal cultures were isolated from freshwater lakes in Hainan, China. Four microalgal isolates were selected because they could be successfully cultivated at high density and demostrated a strong fluorescence after being stained with nile red. These cultures were identified as strains of Chlorella sp. C11, Chlamydomonas reinhardtii C22, Monoraphidium dybowskii C29, and Chlorella sp. HK12 through microscopic and 18S rDNA analysis. Under similar conditions, the lipid productivity of Chlorella sp. C11, Chla. reinhardtii C22, M. dybowskii C29 , and Chlorella sp. HK12 were 1.88, 2.79, 2.00, and 3.25 g L-1, respectively. Chla. reinhardtii C22 yielded a higher lipid content (51%), with a lower biomass concentration (5.47 g dwt L-1). Chlorella sp. HK12 reached a growth rate of 0.88 day-1 at OD540nm and yielded a biomass concentration of 7.56 g dwt L-1, with a high lipid content of 43%. Gas chromatography/ mass spectrometry analysis indicated that lipid fraction mainly comprises hydrocarbons including palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acids. Our results suggest that Chlorella sp. HK12 is a promising species for biodiesel production, because of its high lipid productivity and a relatively high content of oleic acid. PDF
The decay resistance of oil-heat treated aspen wood (Populus tremula l.) against white rot fungi (Coriolus versicolor) and brown rot fungi (Coniophora puteana) was investigated. Three different temperature stages and two time levels for oil heat treatment for the selection of optimum conditions were determined. Linseed oil as a heating medium was used. The mass loss of treated samples that were exposed to both fungi was significantly lower than that of the control samples. Results also showed improvement in dimensional stability after oil heat treatment. Decay resistance and dimensional stability of aspen wood were increased significantly with temperature increasing, but time seemed to have no effect on those properties. Oil heat treatment is a suitable method to improve decay resistance of aspen wood as it reduced the mass loss by 71% and 77% against Coriolus versicolor and Coniophora puteana compared with control samples, respectively. On the other hand, oil heat treatment improved the dimensional stability by about 20.5%. PDF
Galai, S., Touhami, Y., and Marzouki, M. N. (2012). "Response surface methodology applied to laccases activities exhibited by Stenotrophomonas maltophilia AAP56 in different growth conditions," BioRes. 7(1), 706-726.
Stenotrophomonas maltophilia AAP56, laccase-producing bacteria, growing under different conditions, exhibit laccase activity that is highly affected by some environmental factors. Response surface methodology (RSM) was applied for the determination of laccase factor dependence using two substrates: ABTS (2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) and DMP (2,6 Dimethoxy-phenol). RSM was carried out with a 24 factorial design using four variables, namely, dye (0 to 0.1 mg mL-1), Cu in Med (0 to 400 µM), shaking (0 to 150 rpm), and CuSO4 in assay (0 to 0.2 mM). Significant correlation between the effects of these variables on R1 (ABTS oxidase activity) and R2 (DMP oxidase activity) responses was detected. Astonishing results showed differences between these two activities with respect to copper activity dependence. Anoxic conditions exhibited a significant ability to induce the enzyme. This bacterial laccase activity (produced under optimal conditions according to RSM) was used to decolorize an azoic dye, Reactive Black 5 (RB5). It was efficient only in the presence of a redox mediator to degrade RB5 after 20 min of incubation time. PDF
Park, N.-J., Lim, H. K., Song, H. Y., Kim, D. R., Lee, K.-I., and Hwang, I. T. (2012). "Cloning, expression, and characterization of an alkalophillic endo-1,4-beta-xylanase from Paenibacillus sp. HPL-002," BioRes. 7(1), 727-742.
The biochemical properties of a purified enzyme of a new alkalophillic endo-1,4-beta-xylanase gene, KRICT PX2 (GU967374), which was isolated from Paenibacillus sp. HPL-002 (KCTC11410BP) and expressed in E. coli, were investigated. The specific activity of the purified xylanase was 51.26 μmol/min/mg proteins. The Km and Vmax values of the protein for birch wood xylan were also verified to have 0.061 μM and 55.3 μmol/min/mg proteins, respectively. The optimum pH and temperature for the activity of the enzyme were pH 8~9 and 50oC, respectively, and, the activity was stably maintained at 40oC. Most metallic salts, ethylenediamine tetra-acetic acid, 2-mercaptoethanol, phenylmethane-sulphonyl fluoride, and furfural, have no impact on the enzyme’s activity at 1 mM. The simulated 3-D structure of this xylanase is similar to Xyn10B from Paenibacillus barcinonensis. Further research on the degradation of different-origin xylans and enzyme production will be necessary for practical applications. PDF
The motivation for this study was to reduce the consumption of C2S when preparing high-viscosity viscose by pre-treating two softwood pulps with enzymes prior to the viscose stages. Reactivity was evaluated in two ways, Fock´s test of the pulp and the gamma number of the viscose solution prior to regeneration. Whilst the reactivity of a pulp that had been subjected to enzyme pretreatment increased according to Fock´s test, it did not increase according to the gamma number. This unexpected difference between the two reactivity tests was investigated. It was concluded that Fock´s test measures the extent to which C2S reacts with a pulp sample during a standardized test, whereas the gamma number measures the resulting degree of xanthate substitution on the cellulose backbone. The gamma number was judged to be the more relevant of the two tests, since it reflects the dissolution ability of a pulp in the viscose preparation. A higher gamma number also means that the coagulation time in the spinning process is prolonged; this is beneficial, as it can be used to increase the tenacity of the viscose fibres. Measuring the reactivity according to Fock´s test, on the contrary, provides more dubious results, as the test has no undisputed correlation to the viscose preparation process. PDF
Alkaline oxidation (AlkOx) is an effective fractionation technique for lignocellulosic raw materials. The efficiency of the AlkOx treatment can further be enhanced by using a catalyst (CatOx). Both CatOx and AlkOx provide a fiber fraction containing readily hydrolysable carbohydrates that can be utilized in biotechnical processes and a liquid fraction containing solubilized lignin and reaction products from various biomass components. The effects of different fractionation conditions on yields and chemical composition of solubilized and insoluble fractions were investigated. Two temperatures and two reaction times were studied with and without a catalyst. The composition and content of carbohydrates in the fiber and liquid fractions were examined. The generation of aliphatic carboxylic acids as oxidation products was also investigated. The catalytically assisted oxidation was more efficient than the alkaline counterpart in dissolution of wood components under a four-hour treatment period resulting in higher dissolution of hemicelluloses. A longer reaction time of 20 hours leveled out the differences between the oxidation processes. Comparison of different bases showed that similar solubilisation of dry matter was obtained with NaOH, KOH, and Na2CO3. Oxidation in Na2CO3 caused higher dissolution of glucomannan and greater acid production. The dissolution of hemicellulose and lignin, and their oxidation to acids was most efficient in the first 4 hours of oxidation. PDF
Nitrogen fixation of wheat straw ammonium sulfite pulping spent liquor and the chelating property of nitrogen-fixed ammonium lignosulfonate were studied. Results showed that free ammonium nitrogen in spent liquor could be fixed by formaldehyde. When the amount of formaldehyde was 10% based on the dry weight of lignosulfonate, 30% of inorganic nitrogen was converted into organic nitrogen, of which 87.4% was ammonium lignosulfonate and 12.6% was urotropine. The proper chelating condition of nitrogen-fixed ammonium lignosulfonate was as follows: pH:3, hydrogen peroxide:10%, FeSO4: 40.9%, and 50 oC for 30 min. Under this reaction condition, the chelating ratio of Fe2+ was measured as 15.1%. Chelation did not result in Fe(OH)3 precipitation under alkaline conditions. Effects of H2O2 dosage on the structure of ammonium lignosulfonate were also studied. The content of carboxyl, phenolic hydroxyl, and conjugated carbonyl groups in lignosulfonate that could be chelated with metal ions increased after ammonium lignosulfonate was oxidized. Average molecular weight and distribution were also determined with GPC. Results showed that the proportion of higher molecular weight components increased after oxidation of ammonium lignosulfonate, indicating that oxidative degradation and condensation reaction proceeded during oxidative treatment and condensation was the main reaction. The increase of molecular weight could improve the chelating ability of ammonium lignosulfonate. PDF
The purpose of this study is to develop a low-formaldehyde-emitting resin system for medium density fibreboards (MDF). A combination of polyamines with phenolic resins seems to be suitable for this purpose. To produce panels with such a resin system, polyethylenimine, and a phenolic resin were separately applied on fibres and subsequently made into boards in a thermal pressing process. It was demonstrated that thickness swelling and the mechanical properties of the boards produced with the new adhesive system were comparable to those conventionally manufactured with urea-formaldehyde resins. Even with adhesive contents of just 2 to 3%, the panels attained satisfactory internal bond strength. MDF panels with a total adhesive content of between 1.25 and 5% were produced from a mixture of polyethylenimine and phenolic resins (resol type) at different ratios. All boards were tested for physical (thickness swelling and water absorption) and mechanical properties (internal bond, modulus of elasticity, flexural strength). It was demonstrated that thickness swelling and the mechanical properties of the boards produced can be improved by a combination of polyethylenimine and phenolic resin. PDF
Changes in color (CIE L*a*b*) and properties (density, mass loss, density loss, and bending properties) of heat-treated beechwood were researched, as well as the possibilities of predicting these properties based on color. Considering the different market values of sapwood and red heartwood, the aim of this study was to establish whether these parts of beechwood differ after a heat treatment. Samples were exposed to temperatures of 170oC, 190oC, and 210oC, respectively, for 4 hours. In order to predict the properties, a linear regression with color change (ΔE) and ΔL predictors was used, as well as the partial least squares (PLS) regression with 12 color variables. It has been shown that heat treatment reduces the properties of sapwood and red heartwood in the same manner, and equalizes the colors. The PLS-R showed the best results of prediction and presented the very high coefficients of determination for the mass loss, density loss, and modulus of rupture (MOR) in both sapwood and red heartwood. The equalized colors of heat-treated red heartwood and sapwood can significantly increase the use of products made out of red heartwood. Color can be an important indicator of the quality of such beechwood. PDF
Methylolurea and carbamide were used to impregnate eucalyptus wood to improve its physical and chemical properties. The physical properties and dimensional stability were examined. TGA was used to evaluate the thermal stability of the wood. FTIR was used to state the changes of functional groups. The changes of wood structure were observed by SEM. The results showed the bending strength and compressive strength parallel to the grain increased by 15.10% and 16.78%, respectively. The basic density of modified wood was improved by 14.29%. The shrinkage of volume and swelling of volume were significantly decreased compared to the untreated wood. The TGA results indicated that the mass loss was around 8% during the second stage, from 120°C up to 280°C, while the mass loss of treated wood was around 4%. The treated wood exhibited LOI (limited oxygen index) values of about 42%, while the natural wood exhibited a LOI value of 22%. The FTIR analysis successfully showed that chemical bond was produced between wood and methylolurea as a result of chemical reaction between wood and methylolurea. The SEM results indicated that the transverse and tangential sections of the treated specimens were filled with the reaction products, which can prevent the absorption of moisture. PDF
Agricultural residues are receiving increasing interest when studying renewable raw materials for industrial use. Residues, generally referred to as nonwood materials, are usually complex materials. Wheat straw is one of the most abundant agricultural residues around the world and is therefore available for extensive industrial use. However, more information of its cell types is needed to utilize wheat straw efficiently in pulp and papermaking. The pulp cell types and particle dimensions of wheat straw were studied, using an optical microscope and an automatic optical fibre analyzer. The role of various cell types in wheat straw pulp and papermaking is discussed. Wheat straw pulp components were categorized according to particle morphology and categorization with an automatic optical analyzer was used to determine wheat straw pulp cell types. The results from automatic optical analysis were compared to those with microscopic analysis and a good correlation was found. Automatic optical analysis was found to be a promising tool for the in-depth analysis of wheat straw pulp cell types. PDF
Ismail, H., Muniandy, K., and Othman, N. (2012). "Fatigue life, morphological studies, and thermal aging of rattan powder-filled natural rubber composites as a function of filler loading and a silane coupling agent," BioRes. 7(1), 841-858.
Fatigue life, morphological studies, and thermal aging properties of rattan powder-filled natural rubber (NR) composites were investigated as a function of filler loading and a silane coupling agent. NR composites were prepared by the incorporation of rattan powder in the range of 0 to 30 phr into a NR matrix with a laboratory size two roll mill. Thermal aging was carried out for 7 and 14 days at a temperature of 70 °C, and tensile testing was performed in order to determine the aging properties. The results indicated that the fatigue life of rattan powder-filled NR composites decreased with increasing rattan powder loading. Tensile strength and elongation at break decreased whilst tensile modulus, stress at 100% elongation (M100), and stress at 300% elongation (M300) increased after aging. Nevertheless, the addition of the silane coupling agent improved both fatigue life and the aging properties of NR composites due to better adhesion between the rubber matrix and the rattan filler which was confirmed by FTIR studies of composites and SEM studies of fatigue fractured surfaces. PDF
Growing public concern about environment and potential risks to health in the polymer and plasticizer industry promises to increase the market for a safer alternative plasticizer such as a vegetable oil-based agent. The purpose of this study was to investigate the potential of crude palm oil as a bio-additive in polypropylene blown films. The polypropylene was blended with 1%, 3%, and 5% dosages of CPO using a twin screw extruder. The extruded samples were blown using the blown thin film technique. Mechanical, physical, and morphological properties were characterized. Modifying polypropylene with CPO showed good enhancement in the mechanical properties of the polypropylene. Tensile strength, elongation at break, impact strength, and tear strength all increased. The scanning electron microscopy photographs of the CPO-modified PP clearly supported the results from the mechanical strength tests. The presence of CPO in the PP matrices decreased the density and increased the melt flow rate. These findings contribute new knowledge to the additives area and give important implications for designing and manufacturing polymer packaging materials. PDF
Precipitation of lignosulphonates from the liquor for sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) by addition of Ca(OH)2 was investigated in this work. The experiment was conducted in a reaction temperature range of 20 to 75oC for 90 minutes with Ca(OH)2 charge varying from 20 to 90 g/L and a range of liquid enrichment ratio of 1 to 5. It was found that increased Ca(OH)2 charge, duration time, reaction temperature, and liquor concentration each tended to improve lignosulphonates precipitation, but tended to hurt fermentable sugars conservation. Application of Ca(OH)2 20 g/L to SPORL liquid without enrichment at 30oC for 90 minutes could be an optimal condition. Under this condition, 25.95% of the lignosulphonates was precipitated for further utilization, while calculated amounts of 106.46% of glucose and 60.25% of xylose were conserved for further fermentation. PDF
The adsorption of cellulases onto fibers may be one of the most important factors affecting the enzymatic reaction between cellulases and fibers. This study investigated the adsorption kinetics involved, using isothermal adsorption equations. Cellulose binding domains (CBDs) were isolated from a commercial cellulase, and their role in the adsorption and enzymatic reaction was evaluated. Approximately 13% to 24% of the refining energy was saved after northern bleached softwood kraft pulp samples were pretreated with full cellulase, CBDs, or cellulase lacking CBDs under optimal conditions. The absence of CBDs in cellulase resulted in less effective enzyme adsorption and hydrolysis of the fibers. These data suggest that pretreatment of northern bleached softwood kraft pulp with CBDs may not only improve the beating degree of the pulp and reduce refining energy consumption but also improve the tensile index of the handsheet. Analysis of the degree of cellulose crystallinity and fiber surface morphology by X-ray diffraction and scanning electron microscopy revealed that the CBDs in cellulase help modify the crystalline area and facilitate the enzymatic degradation of cellulose. The adsorption parameters of the cellulases calculated from isothermal adsorption experiments confirmed the role of CBDs in the adsorption of cellulases onto fibers. PDF
Wood-TiO2 (titania) composites were prepared by a sol-gel process, in which wood was impregnated with the precursor solutions prepared from tetrabutyl titanate (TBT), followed by a curing step. The surface morphology and moisture absorption behavior of the wood composites, as well as their thermal and mechanical performances, were examined. Environmental scanning electron microscopy (ESEM) analysis revealed that TiO2 gels were deposited principally in the cell lumens and partly in the cell walls, as confirmed by the energy dispersive X-ray (EDX) analysis. By this inorganic modification, the hygroscopicity of wood was significantly reduced and its dimensional stability was improved consequently. Greater amounts of TiO2 gel deposited in the cell lumens were not helpful in enhancing the hygroscopicity of wood. Thermal analysis (TG-DTA) showed that the incorporation of TiO2 gel retarded the thermal decomposition of wood matrix and improved the thermal stability of wood. The incorporated inorganic gel seemed to stiffen the wood cell walls, as indicated by the increased resistance of the wood composites to deformation and collapse in compression. PDF
Release paper is a special paper grade with one or both sides coated with non-sticking materials. Silicone is currently the only material used to produce release paper at the industrial level. Its remarkable properties and availability ensure product quality and sustainability of the industrial production. Meanwhile, the stability of silicone polymers raises serious environmental problems in terms of paper substrate recyclability. Studies are currently under way to evaluate the ability of phosphate esters as a new class of compounds capable of developing non-adhesive surface properties. This paper presents initial attempts to coat the paper with phosphate esters and to assess phosphate ester / fibrous substrate and phosphate ester / adhesive interactions. The results show that this class of compounds exhibits non-adhesive properties and, when coated on paper under certain conditions, can lead to a non-sticking surface. Despite the fact that there is a long way to achieve ester anchoring to surface fibers and to control the peeling force from an adhesive tape, preliminary results are encouraging. PDF
The tensile strength behavior and recyclability of the paper prepared with the addition of polyamideamine-epichlorohydrin (PAE) were investigated. The dry and wet tensile strengths obtained with different PAE dosage were measured. The highest wet-to-dry strength ratio of 35% was obtained at 10 mg/g; above this addition level wet strength dropped slightly and then remained constant. The repulpability of strengthened paper was correlated directly with wet strength. The effect of electrolyte on tensile strength was also quantified by varying sodium chloride and calcium chloride concentration in the furnish stock. Without PAE, high salt concentrations (100 mM) reduced the tensile strength by 15-20%. At constant PAE addition level of 10 mg/g, low levels of salt addition (of either 10 mM NaCl or 10 mM CaCl2) slightly improved the strength; paper strength decreased at high salts concentrations. The cation valency and concentration in the process water were important variables which affected the efficiency of PAE. These results present the significance of developing sustainable wet strength agents that can be applied in demanding salty conditions while maintaining the product recyclability. PDF
Fang, C.-H., Cloutier, A., Blanchet, P., and Koubaa, A. (2012). "Densification of wood veneers combined with oil-heat treatment. Part II: Hygroscopicity and mechanical properties," BioRes. 7(1), 925-935.
In an effort to achieve high mechanical performance and improved dimensional stability, densification combined with oil-heat treatment (OHT) was performed. In our previous study, OHT was successfully applied to densified veneer, which resulted in improved dimensional stability. In the present study, the impact of OHT on densified wood veneer hygroscopicity and mechanical properties was determined. OHT at 180, 200, and 220ºC for 1, 2, and 3 hours was applied to densified Aspen (Populus tremuloides) veneers. OHT was found to be an efficient treatment to reduce the hygroscopicity of densified aspen veneers, although OHT had a negative impact on Brinell hardness. However, due to the contribution of densification, the hardness of oil-heat treated veneers was still two to three times higher than that of non-densified veneers. Similar results were found for tensile strength. Bending strength increased slightly at low OHT temperature, and then decreased at high temperature. Bending strength of oil-heat treated densified veneer samples was higher than that of non-densified ones. No significant effect of OHT was found on tensile MOE, but bending MOE increased after OHT. Compared to OHT duration, OHT temperature had a larger impact on densified wood hygroscopicity and mechanical properties. PDF
Danesh, M. A., ZiaeiTabari, H., Hosseinpourpia, R., Nazarnezhad, N., and Shams, M. (2012). "Investigation of the morphological and thermal properties of waste newsprint/ recycled polypropylene/ nanoclay composite," BioRes. 7(1), 936-945.
The main objective of this research was to study the potential of waste polypropylene and waste newsprint fiber for making wood-plastic nanocomposites. We used 30 wt.% waste newsprint fiber and 10 wt.% compatilizer in this study. Nanoclay was used at two levels: 2.5 and 5% by wt. Materials were mixed with either recycled or virgin polypropylene. The effects of nanoclay (NC) on the mechanical and thermal properties were also studied. The improvements in tensile properties of the blended composites with the addition of NC were further supported by Scanning Electron Microscope (SEM) micrographs and X-Ray Diffraction (XRD) data. Thermal degradation behavior of the composites showed that the degradation temperatures shifted to higher values after addition of nanoclay. The XRD data showed that the relative intercalation of composites with 2.5% nanoclay was higher than 5% nanoclay. The experimental results demonstrated that the waste materials could be used as appropriate alternative raw materials for making low cost wood-plastic composites (WPCs). PDF
The effects of using sodium dodecyl sulfate (SDS) and a modified polyacrylic acid solution (MPA) on a soybean meal adhesive were investigated. Three-ply plywood specimens were fabricated to measure the water resistance of the adhesive (three-cycle soak test). The viscosity and solid content of the adhesive were measured. The cross-section and functional groups of the cured adhesive were evaluated using scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The results showed that using SDS improved the water resistance of the soybean meal adhesive by 30%. After incorporating MPA, the water resistance of the soybean meal/SDS/MPA adhesive was further improved by 60%, the viscosity of the adhesive was reduced by 81%, and the solid content of the adhesive increased by 15%. The plywood bonded by the soybean meal/SDS/MPA adhesive met the interior plywood requirements. SEM results showed no holes and cracks on the cross-section of the cured soybean meal/SDS/ MPA adhesive. FTIR analysis indicated that more peptide linkages were formed in the cured adhesive as MPA was incorporated. PDF
Muniandy, K., Ismail, H., and Othman, N. (2012). "Biodegradation, morphological, and FTIR study of rattan powder-filled natural rubber composites as a function of filler loading and silane coupling agent," BioRes. 7(1), 957-971.
Natural rubber (NR) composites were prepared by the incorporation of rattan (Calamus Manan) powder at filler loadings in the range of 0 to 30 phr into a natural rubber matrix with a laboratory size two roll mill. The particle size of rattan powder was less than 180 µm. The biodegradation of the rattan powder-filled natural rubber (NR) composites were investigated as a function of filler loading and a silane coupling agent. A soil burial test was carried out for six months, and the degradation of the NR compound and the NR composites was evaluated through tensile testing. Morphological properties were determined using scanning electron microscopy (SEM) to evaluate the degradation of the samples after six months of soil exposure. The results indicate that the tensile strength, elongation at break, and stress at 100% elongation (M 100) all decreased after soil burial testing due to the biological attack by microbes onto the sample. Improvement in tensile properties was seen with the addition of the silane coupling agent due to better adhesion between the rattan filler and the rubber matrix. The deterioration in tensile properties due to the biodegradation process was confirmed by SEM and FTIR studies. PDF
Catalytic conversion of formic acid into methanol was investigated with Cu as a catalyst and Al as a reductant under hydrothermal conditions. It was found that formic acid can be converted into methanol by such means. The highest yield of methanol (30.4%) was attained with a temperature of 300 °C and a reaction time of 9 h. The AlO(OH) formed from Al oxidation may also play a catalytic role in the formation of methanol. This process may provide a promising solution to producing methanol from carbohydrate biomass combined with the process of converting the carbohydrate into formic acid, which is expected to emit no CO2. PDF
White rot fungi can be used as a pretreatment of biomass to degrade lignin. It also alters the structure of the lignocellulosic matter, thus increasing its accessibility to enzymes able to convert polysaccharides into simple sugars. This study compares the ability of two species of white rot fungi, Pycnoporous sanguineus and Oxyporus latemarginatus FRIM 31, to degrade lignin in kenaf chips. The white rot fungi were originally isolated from the tropical forest in Malaysia. Kenaf chips were first inoculated with each fungus separately using corn steep liquor as a fungal growth promoter. The kenaf chips were inoculated with white rot fungus for a period of 1, 2, 4, 8 and 16 weeks, after which they were observed under the scanning electron microscope (SEM). Chemical analyses were conducted following TAPPI Standard Methods and Fourier Transmission Infra Red (FTIR). SEM observations showed evidence of fungal colonization. When calculating weight loss, both P. sanguineusand O. latemarginatus FRIM 31 showed the greatest reduction. Amounts by mass of cellulose, hemicelluloses, extractives, and lignin in the treated kenaf chips all were lowered. The results show that O. latemarginatus FRIM 31 had a greater ability to degrade lignin when compared to P. sanguineus. PDF
Mg-Al-CO3 LDH was synthetized, using co-precipitation, and was used in flame-retardant paper as filler. The crystallizations, granularities of Mg-Al LDH, and characters of flame-retardant papers were investigated through XRD, FT-IR, TEM, TG-DTA, and SEM techniques. The results indicated that Mg-Al hydrotalcites were layered hexagonal nanoparticles, with high positive charge density, perfectly crystallized structure, and striking performance in furnish retention improvement. Mg-Al hydrotalcites with high whiteness can improve the whiteness of flame-retardant paper; the whiteness of flame-retardant paper increased by 82.1% while the dosage of LDH was 20wt%, but the Mg-Al hydrotalcites affected the strength index of flame-retardant paper adversely. The flame-retardant papers based on fiber using Mg-Al hydrotalcites as fillers showed excellent inflaming retarding performance. The oxygen index of the flame-retardant paper produced was above 25% at the dosage of 20wt%. PDF
Steam explosion pulping was evaluated for oil palm empty fruit bunches fiber. The fiber morphology was observed by SEM and TEM. Results indicated that lignin was molten and the cell wall damaged after the steam explosion pulping and that the fiber was partly separated at the same time. The results of handsheet tests showed that the steam exploded pulp had a high yield (78.2%), good physical properties (especially for ring crush 8.6 N·m/g), and low effluent load (SS=910 mg/L; BOD5=3952 mg/L; CODCr=8140 mg/L). The SEP pulp from oil palm EFB fiber was very suitable for packaging paper when combined with American OCC pulp. PDF
Ebrahimpour Kasmani, J., Talaeipour, M., Hemmasi, A. H., Mahdavi, S., and Samariha, A. (2012). "Biochemimechanical pulping of hornbeam chips with Phanerochaete chrysosporium, " BioRes. 7(1), 1016-1028.
The effect of fungal pretreatment of Hornbeam (Carpinus betulus) wood chips on the performance of treated pulps was studied. The chips were pretreated with P. chrysosporium BKM-1767 fungus at 1, 2, and 4 weeks using an inoculation temperature and relative humidity of 39 oC and 65%, respectively with two pulping times (80 and 90 min) and three sodium sulfite charges (14, 18, and 22%). The cooking temperature of 165 °C, and liquor-to-wood ratio of 7:1 were kept constant. Beating energy consumption showed a maximum savings of 43% for four-week treatment of wood chips with the fungus. The screen yield of the unbleached CMP ranged between 76 and 84% depending on the chip inoculation time and cooking conditions. A decreasing trend in screen yield of the pulp after chips incubation could be explained by the enzyme action on the lignin or polysaccharides. Pulp strengths including tensile, burst, tear, and fold declined with an increase in chip treatment time. Applying 3% H2O2, 4.2% NaOH, 3% NaSiO3, and 0.3% DTPA for 1 hour in two similar stages and 2 weeks fungal pretreatment of chips showed the best optical properties of bleached pulp. After a two-stage H2O2-bleaching sequence, the maximal brightness value for the control and biopulps were 54.8% and 56.2%, respectively. Overall, two-week treatment showed the better performance of P. chrysosporium on Hornbeam chips. PDF
Vaskova, I., Jeng, R., Tyagi, V., Rodriguez, A., and Sain, M. (2012). "Extracellular proteins produced by different species of the fungus Trichoderma on a secondary paper mill sludge substrate," BioRes. 7(1), 1029-1039.
Kraft pulping is the most commonly used pulping process in the pulp and paper industry. In this process wood chips are chemically delignified using sodium sulfide and sodium hydroxide. Delignification is usually followed by mechanical fiberization and a bleaching process of the resulting wood pulp. In addition to lignin-free wood pulp, this process also produces waste that contains residues of used chemicals, lignin, cellulose, hemicelluloses, and small amounts of other wood components. Because of the worldwide large-scale production of paper, the sludge from paper mills contributes significantly to environmental pollution. Although there have been great efforts being made to utilize this lignin-rich material, sludge is mostly disposed in landfills or incinerated in a boiler. This research project used secondary sludge as a substrate for 7 wood-decay fungi taxonomically belonging to the genus Trichoderma. The examined fungi expressed the capability of consuming sludge components as a carbon source to produce extracellular proteins. The proteins were separated by gel electrophoresis. Before and after fungi cultivation, the sludge was analyzed by Fourier transform infrared spectroscopy (FTIR). PDF
The effect of mild acidic and alkaline pretreatments of various plant biomasses on their enzymatic hydrolysis has been studied. The yield of reducing sugars and utilization rate of the biomass were used as reliable characteristics of enzymatic digestibility of the biomasses. The experiments showed that alkaline pretreatment was more efficient than acidic pretreatment. As a result of alkaline pretreatment, a more efficient delignification of the biomasses and considerable improvement of the digestibility parameters were observed. It was found that residual lignin content in the biomass after alkaline pretreatment was related to initial lignin content in untreated biomass. Moreover, residual lignin showed an evident negative effect on enzymatic hydrolysis of pretreated biomass samples, and its removal contributed to higher enzymatic digestibility. It is more preferred to select a mild alkaline pretreatment for biomass that has low content of initial lignin. Such treatment yielded highly delignified biomass with increased percentage of cellulose fraction, which enhanced digestibility at low enzyme loading with a relatively short hydrolysis time. PDF
In this study, an artificial neural network (ANN) approach was employed for modeling the moisture absorption (MA) and thickness swelling (TS) properties of oriented strand board (OSB) in various applications. A series of ANN models were developed for the analysis and prediction of correlations between processing parameters and MA and TS of OSB. An ANN model was found for modeling the effects of OSB treatment variables on the MA and TS. The required data for training and testing of the model were obtained from the experimental results of Salay (2010). In designing this model, the MA and TS of the OSB were determined using OSB treatment variables, including board layup type, resin type, application rate of resin, and wax content. When experimental data and results obtained from the ANN were compared by regression analysis using Matlab, it was determined that both groups of data (test and train) were consistent. It was demonstrated that the well-trained feed forward and back propagation multilayer ANN model is a powerful and sufficient tool for the prediction of MA and TS; therefore, by using ANN outputs, satisfactory results can be estimated, rather than measured and hence time and cost are reduced in all the required experimental activities. PDF
The feasibility of the production of cellulose acetate (CA) from recycled paper dust from carton boxes was examined. Two pre-treatments were carried out on the carton box’s paper dust (CPD) to improve the pulp properties for better effect of synthesis. The results showed that the acid and oxygen-alkaline pretreatments were capable of increasing the alpha-cellulose content from 80.5 percent to 87.3 percent and 85.3 percent, respectively. Both pre-treatments also decreased the hemicellulose and ash contents by more than 50 percent. The degree of substitution (DS) of the resultant CA from pre-treated paper dust was improved from 1.94 to 2.13-2.16. The CA that was synthesized from the recycled paper dust showed comparable DS and had a similar trend of Fourier Transform Infrared (FTIR) spectra. Both pretreated pulps also showed an increment in the degree of crystallinity and had maximum degradation effect of temperature when compared to CPD CA. However, all the cellulose acetates produced showed a lower DS and thermal stability compared to commercial cellulose acetate (C CA). The degree of crystallinity of all the cellulose acetate was decreased in comparison to the original material. PDF
The aim of this study was to investigate the effects of thermally compressed veneer laminating on some of the physical and mechanical properties of particleboard. Oriental beech (Fagus orientalis Lipsky)veneers were compressed under various press conditions. Commercially produced particleboard samples were laminated with such compressed veneer sheets. The density, 2-h and 24-h water absorption (WA) and thickness swelling (TS), bending strength (MOR), and modulus of elasticity (MOE) in the parallel and perpendicular directions to grain orientation were measured. The results showed that all of the particleboards laminated with compressed veneer had higher MOR and MOE values compared to unlaminated particleboard and particleboard laminated with non-compressed veneer. In the sandwiched panels, particleboards laminated with veneer sheets and compressed at a pressure of 4 MPa and a temperature of 150 oC had the highest MOR and MOE values. The MOR and MOE values decreased with increasing temperatures higher than 150 oC. The TS value for 2-h and 24-h immersion times decreased with increasing press temperature. The findings of this work could provide some insight in producing sandwich-type panels with improved properties. It appears that compressed veneer using different press temperatures and pressures could be considered as an alternative way of developing sandwich-type products with satisfactory structural properties. PDF
The influence of three drying schedules on the selected mechanical properties of poplar wood (Populus alba L.) was evaluated in terms of suitability for structural applications. For this purpose, 70 mm-thick poplar lumber was conventionally dried by three different moisture content based schedules of T5-D2, T5-D4, and T5-D6. In these schedules, the wet bulb depression was changed as a means of increasing of the drying intensity. After drying, the mechanical properties of the lumber, including bending properties (MOE and MOR), toughness, shear strength parallel to grain, and tensile strength perpendicular to grain, were measured. Results revealed that the severe drying schedule (T5-D6) caused higher reductions in the mechanical properties of the dried boards, particularly the MOE and MOR. Furthermore, toughness and tensile strength perpendicular to grain were not affected by the increasing of the wet bulb depression. The influence of all the three adopted schedules on the mechanical properties was evaluated using the drying rate, final moisture content gradient, and qualitative characteristics of the dried boards. PDF
Astier, C., Chaleix, V., Faugeron, C., Ropartz, D., Krausz, P., and Gloaguen, V. (2012). "Biosorption of lead(II) on modified barks explained by the hard and soft acids and bases (HSAB) theory," BioRes. 7(1), 1100-1110.
Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of Pb(II) from aqueous solutions was investigated. The polysaccharidic moiety of barks was functionalized by periodate oxidation and derivatized after reductive amination in the presence of aminated oligo-carrageenans. Pb(II) adsorption isotherms of derivatized barks were then determined and compared to the capabilities of crude barks using the Langmuir adsorption model in terms of affinity (b) and maximum binding capacity (qmax). Compared to crude barks, the derivatization of barks by oligo-carrageenans resulted in significant enhancements of qmax and b by up to x8 and x4, respectively. The results obtained from crude barks on chemically grafted carboxylic and sulfated barks are discussed and interpreted through the Hard and Soft Acids and Bases (HSAB) theory. PDF
Cassava residue from breweries is being generated in large amounts in Guangxi Province of China, and this has potential to cause serious environmental problems if disposed of improperly. Two-stage anaerobic fermentation is a promising method for the treatment of such residue. In this study, the effect of feed to microbes ratio (F/M ratio) on the anaerobic acidogenic fermentation of cassava residue was studied to determine the optimal F/M ratio and to maximize the performance in a subsequent methanogenic stage. The experiments were carried out at the F/M ratios of 0.2, 0.61, 1.02, 2.05, 3.07, and 4.09 g cassava-TS/g sludge-VSS in six laboratory-scale, completely stirred, tank reactors (CSTR) at mesophilic temperature (35°C). An F/M ratio of 1.02 g cassava-TS/g sludge-VSS resulted in the highest solid removal efficiency and VFA/COD ratio, while starch removal efficiency was still near 100 percent, and acidification was relatively high. As a further benefit, the VFA distribution was more suitable for the subsequent methanogenic fermentation stage. PDF
Heat treatment often brings about some negative effects on mechanical properties of wood. Chinese fir is currently underutilized due to some inherent properties that limit its further applications. Using steam as a heating medium and a shielding gas, the heartwood and sapwood of Chinese fir were treated at a temperature ranging from 170ºC to 230ºC and time from 1 to 5 hours in an airtight chamber. Both the modulus of rupture (MOR) and modulus of elasticity (MOE) were increased for the sapwood specimens under the temperature less than 200ºC for short treatment times. The hardness was increased for both two kinds of specimens under the temperature less than or about 200ºC, compared to the untreated specimens. The temperature has a stronger effect on mechanical properties of wood than the time, and the temperature of 200 ºC is a critical point in modifying mechanical properties of wood. PDF
In this study, several kraft pulps were produced by kraft pulping of fast-growing Eucalyptus with a wide range of cooking conditions. The dependences between pulp yields and some pulp properties, namely, kappa number, HexA contents, and cellulose viscosities, were well investigated. It was found that kraft pulp yields linearly decreased with the reduction of HexA-free kappa number in two different stages, respectively, in which a transition point of measured pulp yield of 48.7% was observed. A similar relationship between pulp yield and HexA was also found, in which the resulting transition point of HexA content was 67 μmol/g. Moreover, the logarithm of pulp viscosity was linearly proportional to the reduction of lignin-free pulp yields. Then, a novel empirical model was successfully developed based on these findings. The parameters in this empirical model were calculated by least-squares estimation using the experimental data from active alkali values of 13.2, 14.7 and 17.8. Another data set was used to verify the effectiveness of this model in predicting the pulp yields. Finally, a good agreement (a linear regression coefficient of 90.59%) between experimental and fitting data was obtained, which indicated that the kraft pulp yield of fast-growing Eucalyptus could be accurately predicted by this novel empirical model. PDF
Sodium lignosulfonate (SL) fractions with narrow molecular weight distribution and known salt content were used to investigate p–p stacking of the aromatic groups in SL. Results show that the charge-free aromatic groups of SL tend to form oriented p–p stacking with the spectroscopic characteristics of J–aggregates. The formation of J–aggregates in SL are recognized by a significant spectral red shift in fluorescent excitation spectra. The other effects that may cause spectral shift, such as the SL species, solvent effect, and the impurities, are investigated to confirm that the formation of J-aggregates is the only viable explanation for the significant spectral redshift of SL. Salt causes molecular shrinkage of SL polyelectrolytes, but has no influence on J–aggregates of the aromatic groups as detected by lack of spectral shift, indicating that the aromatic groups are charge-free. This suggests that not all the aromatic groups but only the charge-free aromatic groups can form p–p stacking. This work demonstrates the presence of J–aggregation in aqueous SL solutions for the first time, which gives an insight in understanding the preferred orientation of the aromatic groups in lignin-based biopolymers. PDF
The aim of this study was to investigate the effects of oxygen and moisture content (MC) on the chemical and color changes of black locust (Robinia pseudoacacia) wood during heat treatment. The wood flour was conditioned to different initial MCs and heated for 24 h at a constant temperature of 120ºC in either oxygen or nitrogen atmosphere. The pH values and chromaticity indexes were examined. Diffuse reflectance UV-Vis (DRUV) and Fourier transform infrared (FTIR) spectra were used to characterize the changes of chromophores upon heating. The study demonstrated that the pH values decreased after heat treatment, and it was lower when the heat treated was in oxygen than in nitrogen. The L* decreased significantly, while a* and b* increased. The total color difference ΔE* increased with increasing initial MC until a plateau was reached after 30% MC. The color change was greater in oxygen than in nitrogen. The hydroxyl groups decreased after heat treatment. The releases of acid and formation of quinoid compounds and carboxylic groups during heat treatment were confirmed. Discoloration of wood is due mainly to the condensation and oxidation reactions, which are accelerated by oxygen. Higher MCs are required to obtain the greatest color change of wood in inert atmosphere. PDF
Asgher, M., Iqbal, H. M. N., and Asad, M. J. (2012). "Kinetic characterization of purified laccase produced from Trametes versicolor IBL-04 in solid state bio-processing of corncobs," BioRes. 7(1), 1171-1188.
A locally isolated white rot fungal strain Trametes versicolor IBL-04 produced high laccase activities in solid state bio-processing of corn cobs. Addition of glucose and yeast extract (C: N ratio; 25:1) enhanced laccase synthesis. Addition of Tween-80 and CuSO4 enhanced laccase production to 1012 U/mL under optimized process conditions. Laccase was further purified to 2.89-fold (specific activity of 840 U/mg) by ammonium sulfate fractional precipitation, dialysis, and Sephadex G-100 gel filtration chromatography. The purified laccase had a relative molecular mass of 63 kDa as detected by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Best enzyme activity was at pH 5 and 40oC. Using 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as substrate, the enzyme showed maximum activity (Vmax) of 780 U/mL with a corresponding Michaelis constant (Km) value of 73µM. Among the different activators/inhibitors, Cu2+, Mn2+, and Fe2+ stimulated laccase activity, whereas EDTA and cystein inhibited the enzyme. The higher Vmax and lower Km for T. versicolor IBL-04laccase as compared to most of the reported laccases suggests its potential for industrial applications. PDF
Kunjadia, P. D., Patel, F. D., Nagee, A., Mukhopadhyaya, P. N., and Dave, G. S. (2012). "Crystal violet (triphenylmethane dye) decolorization potential of Pleurotus ostreatus (MTCC 142)," BioRes. 7(1), 1189-1199.
The extracellular enzyme production capacity of Pleurotus ostreatus MTCC 142 was investigated for decolorization of crystal violet under solid and submerged conditions. Laccases are the major extracellular lignocellulolytic enzymes produced by fungus. Pleurotus ostreatus provided an effective decolorization of dye at 20 mg/L concentration up to 92%. Mycelial growth was observed maximum on plate for a dye concentration 20 mg/L while lowest on 200 mg/L on day 12, respectively. At all concentrations of dye studied, maximum laccase activity was observed on day 8. For 20 mg/L of dye laccase activity was 133 U/L. The decolorization was attributed to microbial action and without role of pH change; less than 0.4 pH change was observed. Manganese dependent peroxidase activity was 106 U/L, maximum on day 8 incubated with 20 mg/L dye concentration. The present study suggested that the high efficiency decolorization of crystal violet by P. ostreatus was assisted by laccase and manganese-dependent peroxidase activity and can be exploited as a promising in biological treatment of waste water containing crystal violet. PDF
Abed, I., Paraschiv, M., Loubar, K., Zagrouba, F., and Tazerout, M. (2012). "Thermogravimetric investigation and thermal conversion kinetics of typical North African and Middle Eastern lignocellulosic wastes," BioRes. 7(1), 1200-1220.
The aim of this work was to thermally characterize the renewable lignocellulosic bioresources derived from palm trees in order to highlight their energy potential. Pyrolysis and combustion behaviours of date stones (DS) agricultural by-products were tested by thermo-gravimetric analysis, and the main chemical compositions were analyzed. The work has also been conducted to identify their most important physical characteristics. The study of the sizes and heating rate effects constitute the first part of the experimental work. Inert atmosphere and three heating rates: 10, 20, and 50 °C/min, were applied to various particle sizes of DS. In the second part, tests were carried out in an oxidizing atmosphere (21% O2) by varying the size of the DS. The kinetic parameters such as pre-exponential factor and activation energy were determined. Increasing the particle sizes and the heating rates didn’t have an appreciable influence on the global weight losses. However, degradation rates were significant with the porous structure of the DS. Weight losses in inert and oxidizing atmospheres were found to occur in two stages (drying and devolatilization) and in three stages (drying, devolatilization, and oxidation of the char). PDF
Islam, M. S., Hamdan, S., Rusop, M., Rahman, M. R., Ahmed, A. S., and Mohd Idrus, M. A. M. (2012). "Dimensional stability and water repellent efficiency measurement of chemically modified tropical light hardwood," BioRes. 7(1), 1221-1231.
Chemical modification is an often-followed route to improve physical and mechanical properties of solid wood materials. In this study five kinds of tropical light hardwoods species, namely jelutong (Dyera costulata), terbulan(Endospermum diadenum), batai (Paraserianthes moluccana), rubberwood (Hevea brasiliensis), and pulai (Alstonia pneumatophora), were chemically modified with benzene diazonium salt to improve their dimensional stability and water repellent efficiency. The dimensional stability of treated samples in terms of volumetric swelling coefficient (S) and anti-swelling-efficiency (ASE) were found to improve with treatment. The water repellent efficiency (WRE) values also seemed to improve considerably with treatment of wood samples. Furthermore, treated wood samples had lower water and moisture absorption compared to that of untreated ones. PDF
The mechanical properties and structure of cactus Opuntia ficus-indica spines were characterised in bending and by means of x-ray diffraction. Using spruce wood cell walls for reference, the modulus of elasticity of Opuntia cactus spines was high in absolute terms, but comparable when specific values were considered, which can be explained by similarities in the cell wall structure of both materials. Differently from the modulus of elasticity, the bending strength of cactus spines was unexpectedly high both in absolute and in specific terms. The unique cellulose-arabinan composite structure of cactus spines, together with high cellulose crystallinity, may explain this finding. PDF
The easy leaching of boron from wood preservation formulations has limited the use of this highly active fungicide. The recently discovered adduct with flavonoids allows boron to be retained for longer periods of time within wood and consequently to extend its life. Two different leaching treatments were compared, and the fungal and termite decay were examined. The biological tests showed extremely high resistance of the leached samples against both fungus (Coriolus Versicolor and Coniophora Puteana) and termites (Reticulitermes Santonensis). The retention of 2.5 kg/m³ was determined as the threshold of efficacy of boron in flavonoid-based wood preservative. Furthermore, solid state 13C-NMR analysis of the tannin resin indicated that boron can be covalently fixed to the tannin-hexamine network. PDF
Acoustic emission (AE) and radial dimensional changes during dehydration under ambient conditions were compared between fully saturated fresh Norway spruce (Picea abies (L.) Karst.) sapwood and sapwood exposed to one or two rewetting-dehydration cycles. The aim of the study was to find out whether AE detected by wideband transducers (100 to 1000 kHz) gives useful information about the mechanical stresses generated during dehydration of small sapwood specimens. AE activity and peak amplitudes became lower after each dehydration-rewetting run. During the first dehydration run the highest peak amplitudes were detected at moderate moisture loss, whereas rewetted wood peaked towards the end of dehydration. AE of fresh, never-dried sapwood was also characterized by a higher count rate of low frequency AE (<175 kHz). Differences in amplitude and frequency clusters between small earlywood and latewood specimens suggest that earlywood is much more sensitive to irreversible processes upon drying than latewood, which might be related to pit functioning and shrinkage anisotropy. At moderate moisture loss, fresh, never-dried sapwood showed higher radial dimensional changes compared to re-wetted sapwood. If it is assumed that fresh, never-dried sapwood is more prone to dehydration stresses than pre-dried sapwood, critical stages during drying can be characterized by high mean peak amplitudes and by a higher count rate of low frequency AE. PDF
Baillères, H., Hopewell, G., Boughton, G., and Brancheriau, L. (2012). "Strength and stiffness assessment technologies for improving grading effectiveness of radiata pine wood," BioRes. 7(1), 1264-1282.
This work was designed to provide the Australian structural radiata pine processing industry with some indications for improving stress grading methods and/or technologies to give an increase in structural grade yields, and significantly reduce processing costs without compromising product quality. To achieve this, advanced statistical techniques were used in conjunction with state-of-the-art property measurement systems applied to the same sample of sawn timber. Acoustic vibration analyses were conducted on green and dry boards. Raw data from existing in-line systems was captured on the same boards. The Metriguard HCLT stress rating system was used as the “reference” machine grading because of its current common use in the industry. A WoodEye® optical scanning system and an X-ray LHG scanner were also able to provide relevant information on knots. The data set was analyzed using classical and advanced statistical tools to provide correlations between data sets, and to develop efficient strength and stiffness prediction equations. Reductions in non-structural dry volumes can be achieved. PDF
Moisture sorption in wood-plastic composites (WPCs) affects their durability and dimensional stability. In certain outdoor exposures, the moisture properties of WPCs are altered due to e.g. cracks induced by swelling and shrinkage of the components, as well as UV degradation or biological attack. The aim of this work was to study the effect of different artificial ageing routes on the moisture sorption properties of WPCs. Extruded WPCs were prepared with either unmodified or acetylated wood and recycled high-density polyethylene (HDPE). The WPC samples were artificially aged involving water soaking, artificial weathering, and white- or brown-rot decay in different combinations. After the ageing, the samples were conditioned in either 65% or 90% relative humidity (RH) until equilibrium moisture content was reached. A dynamic moisture sorption analyzer was used to monitor the sorption rate of samples subjected to a climate change from 65% to 90% RH. Scanning electron microscopy was used to study the surface morphology of the aged composites. Results showed that the artificial weathering caused cracking of the HDPE matrix at the composite surface, as well as a wood-matrix debonding, resulting in an increased moisture sorption rate. The WPC samples subjected to white-rot decay showed the highest moisture sorption rate. PDF
Cellulose and hemicellulose account for a large portion of the world’s plant biomass. In nature, these polysaccharides are intertwined, forming complex materials that require multiple enzymes to degrade them. Multi-enzyme complexes (MECs) consist of a number of enzymes working in close proximity and synergistically to degrade complex substrates with higher efficiency than individual enzymes. The aim of this study was to isolate and characterise a (hemi-) cellulolytic MEC from the aerobic bacterium, Bacillus subtilis SJ01, using ultrafiltration followed by size-exclusion chromatography on a Sephacryl S-400 column. Two MECs, C1 and C2 of 371 and 267 kDa, respectively, were purified, consisting of 16 and 18 subunits, respectively, five of which degraded birchwood and oat spelt xylan. The MECs degraded xylan substrates (C1: 0.24 U/mg, C2: 0.14 U/mg birchwood xylan) with higher efficiency than amorphous cellulose substrates (C1: 0.002 U/mg, C2: 0.01 U/mg carboxymethyl cellulose - CMC). Low or no binding to insoluble substrates indicated that the MECs lacked some of the features characteristic of cellulosomes. The significance of this study lies in the discovery of MECs that differ structurally from cellulosomes that can hydrolyse substrates with high hemicellulose content. PDF
López, J. P., Mutjé, P., Pèlach, M. À., El Mansouri, N.-E., Boufi, S., and Vilaseca, F. (2012). "Analysis of the tensile modulus of polypropylene composites reinforced with stone groundwood fibers," BioRes. 7(1), 1310-1323.
One of the most relevant properties of composite materials to be considered is stiffness. Fiberglass has been used traditionally as a fibrous reinforcing element when stiff materials are required. However, natural fibers are been exploited as replacements for synthetic fibers to satisfy environmental concerns. Among the different natural fibers, wood fibers show the combination of relatively high aspect ratio, good specific stiffness and strength, low density, low cost, and less variability than other natural fibers of such those from annual crops. In this work, composites from polypropylene and stone groundwood fibers from softwood were prepared and mechanically characterized under tensile loads. The Young’s moduli of the ensuing composites were analyzed and their micromechanics aspects evaluated. The reinforcing effect of stone groundwood fibers was compared to that of conventional reinforcement such fiberglass. The Halpin-Tsai model with the modification proposed by Tsai-Pagano accounted fairly for the behavior of PP composites reinforced with stone groundwood fibers. It was also demonstrated that the aspect ratio of the reinforcement plays a role in the Young’s modulus of injection molded specimens. PDF
The effect of heat-dispersing on sticky substances in a deinking pulping line was studied under different conditions including varying temperature, disc clearance, and pulp consistency. Sticky substances were quantitatively investigated before and after the heat-dispersing, and categorized into macro-, mini-, and micro-stickies as well as dissolved and colloidal substances. Meanwhile, their extents of removal in post-flotation were evaluated. The results showed that raising temperature, reducing disc clearance, or increasing pulp consistency significantly improved the dispersion of sticky particles, an effect that will be beneficial to their removal in the subsequent flotation process. Under temperature of 100 °C, disc clearance of 0.3 mm, and pulp consistency of 30%, macro- and mini-stickies decreased by 92% and 83%, respectively. Due to being dispersed to smaller sizes, removals of mini- and micro-stickies were enhanced in post-flotation to 25-26% and 68-70%, respectively. Only a small amount of dissolved and colloidal substances was removed in flotation. PDF
Yoshihara, H. (2012). "Influence of the specimen depth to length ratio and lamination construction on Young's modulus and in-plane shear modulus of plywood measured by flexural vibration," BioRes. 7(1), 1337-1351.
In this study, the Young’s modulus and the in-plane shear modulus of 3-, 5-, and, 7-ply Lauan wood (Shorea sp.) were determined by conducting a flexural vibration test with various specimen depth to length ratios and performing a subsequent finite element analysis (FEA). The length and depth directions of the specimen used for the vibration test coincided with the length/width and width/length directions of the plywood panel. The results obtained from the experiment and FEA revealed that the influence of specimen configuration and lamination construction did not significantly affect the measurement of the Young’s modulus. However, the results suggested that the in-plane shear modulus decreased as the depth to length ratio of the specimen decreased. The FEA result suggested that this decreasing tendency is more pronounced as the ply number decreases and the thickness of the plywood increases. A statistical analysis on the experimental results suggested that the length of the specimen must be less than 10 times the depth to reduce the influence of specimen configuration on the measured value of the in-plane shear modulus. PDF
Hashim, R., Wan Nadhari, W. N. A., Sulaiman, O., Sato, M., Hiziroglu, S., Kawamura, F., Sugimoto, T., Seng, T. G., and Tanaka, R. (2012). "Properties of binderless particleboard panels manufactured from oil palm biomass," BioRes. 7(1), 1352-1365.
The objective of the study was to investigate physical and mechanical properties of experimental particleboard panels manufactured from oil palm (Elaeis guineensis) biomass without using any adhesives. Different parts of oil palm, including the core and mid sections of trunks, fronds, bark, and leaves, were used to make the panels with an average target density of 0.80g/cm3. Based on the test results, it seems that panels made from bark and leaves did not have satisfactory strength and dimensional stability. However, the panels having particles from the core portion of the trunks exhibited the highest modulus of rupture and internal bond strength but lowest in thickness swelling and water absorption values among the samples. The panels made with particles of mid-section of trunks and fronds followed the samples having core portion trunks material. Three types of raw material, namely fronds, mid-, and core-parts of the trunks appeared as though they could have potential to manufacture particleboard panels with acceptable properties based on requirements stated in Japanese Industrial Standard (JIS). Similar to the above findings, surface quality of the samples were also found acceptable for the panels made from three types of particles. Based on the results of this work, oil palm in the form of biomass could be considered as an environmentally friendly alternative raw material to manufacture binderless particleboard panels. PDF
Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade (from rhodamine dye) is resistant to conventional bleaching treatments. This largely limits the use of deinked pulp in white paper grades. In this review, the available technologies for process water decolorization are discussed (chemical methods, physico-chemical methods and biological treatments). Ozonation of the process water appears to be the most promising technique for decolorization of process water in deinking mills. Other emerging technologies such as photo-catalytic treatment or mineralization by white-rot fungi (after adsorption on low-cost agricultural residues) should be considered as well. PDF