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BioResources Competition Print Edition
In this special "Print Edition", BioResources is proud to feature the winners of the 2014 contest for "best papers". Articles published during 2013 were considered in this contest. In the first round of the competition, a pool of articles was selected based on the number of times that they have been cited in peer-reviewed journals. In the second round, the articles were judged by a panel that included all of the full-time staff of BioResources plus most of the members of the journal's Editorial Board. The articles receiving the most votes were judged to be the winners.
Congratulations to the winning authors!
Biochar is an effective means to withdraw carbon dioxide (CO2) from the atmosphere and consequently influence the trend of global climate change. However, there still are substantial knowledge gaps for this idea to be applicable. One big question is how to produce biochar from biomass on a large scale. Our idea is to use biogas produced from agricultural wastes as thermal energy for biochar production from cheap crop residues. A continuous biogas-energy pyrolysis system has been designed and successfully piloted to utilize crop residues for biochar production. PDF
Forests have long-standing relationships with humanity beyond the material aspects. Recreation is an essential human need, and forests possess intrinsic values to support such a need in direct, authentic, and emotional ways. Quality recreation experiences can lead to a greater appreciation of bioresources and deeper support for forest conservation. The forest-recreation connections should be celebrated and sustained in this age of rapid social, environmental, and technological changes. PDF
Native galactoglucomannans (GGMs), which were isolated from thermomechanical pulping waters of Norway spruce, were modified through cationization, carboxymethylation, and imination at the reducing end with a primary long-chain hydrocarbon amine. The derivatives were tested for their papermaking properties. The native GGMs increased the wet tensile strength as a result of the dispersion of fibrils in the wet fibre web. In wood-containing paper, GGMs increased the retention of fines and extractives without a decrease in paper strength. The GGMs also flocculated fillers effectively. The cationic GGMs were able to interact between fibrous fine material and fibres, as well as with fillers. Therefore, an electrostatic mechanism of action is suggested. Carboxymethylated GGMs are believed to bind to fibres and fines through divalent metal ions present in wood. For the amphiphilic amine-modified GGMs, the alkane chain attached to the reducing end appeared to play a key role. The tail was orientated towards the hydrophobic particles; the resulting paper was the most hydrophilic, since the hydrophobic particles were covered with the polysaccharide. Based on the present results, it can be concluded that galactoglucomannans can be modified to yield new and interesting functionalities to wet-end additives for papermaking and other purposes. PDF
Cellulosic fibers in Oil Palm Empty Fruit Bunches (OPEFB) are tightly packed with lignin, hemicelluloses, small depositions of wax, and inorganic elements. In the present work, eco-friendly reagents with low concentrations of 20% (v/v) formic acid and 10% (v/v) of 30% hydrogen peroxide were employed at 85 ºC for the extraction of cellulose from OPEFB. The yield of 64% (w/w) achieved was among the highest ever reported. Based on the XRD, the alpha-cellulose content was 93.7% with a high crystallinity of 69.9%. The average diameter was 13.5 μm with structural evidence of separated fibrils as investigated by FESEM. The TEM analysis suggested that the material was crystalline and its geometry was a monoclinic structure. The FTIR spectral peaks representing wax and hemicelluloses at 1735 cm-1 and 1375 cm-1, respectively, and lignin at 1248 cm-1 and 1037 cm-1, were not observed in the extracted OPEFB-cellulose spectra. Based on the TGA results, thermal stability at 325 ºC with a single degradation curve suggests the purity of OPEFB-cellulose. PDF
Sabo, R., Jin, L., Stark, N., and Ibach, R. E. (2013). "Effect of environmental conditions on the mechanical properties and fungal degradation of polycaprolactone/microcrystalline cellulose/wood flour composites," BioRes. 8(3), 3322-3335.
Polycaprolactone (PCL) filled with microcrystalline cellulose (MCC), wood flour (WF), or both were characterized before and after exposure to various environmental conditions for 60 days. PCL/WF composites had the greatest tensile strength and modulus compared to neat PCL or PCL composites containing MCC. Electron microscopy indicated better adhesion between WF particles and PCL than between MCC particles and PCL. Neither wood flour nor MCC cellulose appeared to significantly affect the crystallinity of PCL. Environmental conditioning resulted in only minor deterioration of mechanical properties, although samples soaked in water had greater deterioration of mechanical properties than those in high humidity or freezing environments. After a modified 12-week soil block test, specimens made with wood flour lost weight and showed signs of decay after exposure to the brown-rot fungus Gloeophyllum trabeum. PDF
A simple strategy is reported for catalytic conversion of glucose to 5-hydroxymethylfurfural (HMF) over AlI3 in N,N-dimethylacetamide (DMAC). When the reaction was conducted in DMAC at 120°C for 15 min over AlI3 catalyst, HMF was obtained with a yield of 52%. The reaction course was monitored by 13C NMR spectroscopy and HPLC analysis. The results suggest that AlI3 catalyzes the three consecutive reactions consisting of mutarotation of α-glucopyranose to β-glucopyranose, isomerization of glucose to fructose, and dehydration of fructose to HMF. PDF
Two series of rosin quaternary ammonium salts (QAS) were synthesized using the same path. The structure of the target products was characterized by HPLC, MS, IR, and 1HNMR, and the bioactivity was determined by filter paper method using Trametes versicolor(white-rot fungus) and Gloeophyllum trabeum (brown-rot fungus), which are two kinds of general wood decay fungi in nature. The results showed that all compounds tested had a satisfactory anti-fungal effect at the molarity of 0.025 mmol/mL. Hereinto, acrylpimaric Gemini QAS had better bioactivity than dehydrogenated or tetrahydrogenated rosin QAS against Trametes versicolor. To this fungus, quaternary ammonium groups, which wraps up the membrane of microorganism and disrupts the balance in cell membrane, plays the leading role for its bioactivity. ToGloeophyllum trabeum, the inhibition activity of acrylpimaric QAS and dehydrogenated rosin QAS are almost at the same level and larger than tetrahydrogenated rosin QAS, so we conclude that both quaternary ammonium group and aromatic group play important roles. Compared with dodecyl dimethyl benzyl ammonium chloride (1227), which is a commercially available quaternary ammonium salt type fungicide, acrylpimaric acid quaternary ammonium salts have approximate bioactivity against Gloeophyllum trabeum. In conclusion, rosin derivatives with functional groups would do well in wood preservative applications. PDF
Min, D.-Y., Smith, S. W., Chang, H.-M., and Jameel, H. (2013). "Influence of isolation condition on structure of milled wood lignin characterized by quantitative 13C nuclear magnetic resonance spectroscopy," BioRes. 8(2), 1790-1800.
Milled wood lignin (MWL) was widely characterized to demonstrate the structure of native lignin by liquid state 13C NMR. As an isolated lignin, the structure of MWL was influenced by the isolation procedure performed. In this article, hardwood (sweetgum) and softwood (loblolly pine) were subjected to various isolation conditions to elucidate the effect of extracting temperature and milling time on the structure of MWL. Purification was also carried out on the crude MWL. The structure of the crude MWL and the purified MWL was identified and quantified by 13C NMR. Based on the yield and the lignin content of the crude MWL, the optimal isolation was achieved with 8 h milling and 20 °C extracting for hardwood. For softwood, the optimal isolation condition for crude MWL was 12 h milling and 20 °C extracting. PDF
Aging systems of wine brandies have been a target of investigation to reduce the costs and aging time. In this study, the extractives and Klason lignin contents of wood fragments used in the aging of wine brandies in stainless steel tanks were evaluated. Two types of wood fragments, known as staves and tablets, and two wood botanical species, Limousin oak (Quercus robur L. from the Limousin region of France) and Portuguese chestnut (Castanea sativa Mill.), with heavy toasting levels were used. The wood extractive and Klason lignin contents were analyzed before and 30 months after the aging of wine brandy. The results showed that the chestnut wood presented the highest content of extractives, while the Klason and total lignin contents were higher in the oak wood. A highly significant effect from the tablets was found on the extractives and Klason lignin contents, while the soluble lignin content was more affected by the staves. Oxygenation of the wine brandies during the aging process negatively affected the release of extractives and lignin from the wood to the brandy, and therefore will impact the overall quality of the brandy. PDF
Cellulose derivatives, i.e. cellulose functionalized in a solvent state with various side groups, are an important source of biomaterials for food packaging. This review considers the following materials: i) cellophane, ii) cellulose acetate, iii) methylcellulose, and iv) carboxymethylcellulose. Mechanical and barrier properties are important for freestanding packaging films as well as for coatings. The potential of the selected cellulose derivatives and cellophane is thus examined from the viewpoint of their tensile properties as well as their moisture and oxygen barrier properties. The capacity of microcrystalline cellulose and nano-sized celluloses to reinforce the films and to help impede gas diffusion is examined for microfibrillar celluloses, nanocrystalline celluloses, and whiskers. Very good oxygen barrier properties have been reported for cellophane. Nanocellulose fillers have regularly been shown to enhance the tensile properties of several cellulose derivatives, but the effects on the water vapor permeability (WVP) have been studied less often. PDF
The cleavage of lignin bonds in a wood matrix is an important step in the processes employed in both the biorefinery and pulp and paper industries. β-O-4 ether linkages are susceptible to both acidic and alkaline hydrolysis. The cleavage of α-ether linkages rapidly occurs under mildly acidic reaction conditions, resulting in lower molecular weight lignin fragments. Acidic reactions are typically employed in the biorefinery industries, while alkaline reactions are more typically employed in the pulp and paper industries, especially in the kraft pulping process. By better understanding lignin reactions and reaction conditions, it may be possible to improve silvicultural and breeding programs to enhance the formation of easily removable lignin, as opposed to more chemically resistant lignin structures. In hardwood species, the S/G ratio has been successfully correlated to the amount of β-O-4 ether linkages present in the lignin and the ease of pulping reactions. PDF
In the production of paper, especially when using mechanical pulp or recovered wood-containing paper, a large amount of dissolved and colloidal substances (DCS), mainly composed of hemicelluloses, extractives, lignans, and lignin-related substances, are released from the pulp and dissolved or dispersed into the process water. The accumulation of DCS during the papermaking operations due to the closure of process water systems gives rise to various detrimental impacts on the papermaking process and the resulting paper products. Thus it is indispensible to remove or control the DCS in order to overcome or alleviate their negative influences. This review emphasizes recent advances in control of DCS by physical, chemical, and biological methods. The widely used fixatives such as aluminum sulfate, poly-(aluminum chloride), polyamines, polyvinyl amine, and highly cationic starch, as well as their functional effectiveness, mechanism, influencing factors, and influences on paper products are considered. Simultaneously, biological treatments including fungal treatment and enzymatic treatments with lipase, pectinase, laccase, and immobilized enzymes, are also assessed in detail. DCS control has been an important way to improve the runnability of paper machines and the quality of wood-containing paper and recycled paper products. Advances in DCS control are likely to create additional benefits to the papermaking industry in the coming years. PDF