Thomas E. Amidon

Water-based woody biorefinery.

The conversion of biomass into chemicals and energy is essential in order to sustain our present way of life. Fossil fuels are currently the predominant energy source, but fossil deposits are limited and not renewable. Biomass is a reliable potential source of materials, chemicals and energy that can be replenished to keep pace with our needs. A biorefinery is a concept for the collection of processes used to convert biomass into materials, chemicals and energy. The biorefinery is a catch and release method for using carbon that is beneficial to both the environment and the economy. In this study, we discuss three elements of a wood-based biorefinery, as proposed by the SUNY College of Environmental Science and Forestry (ESF): hot-water extraction, hydrolysis, and membrane separation/concentration. Hemicelluloses are the most easily separable main component of woody biomass and thus form the bulk of the extracts obtained by hot-water extraction of woody biomass. Hot-water extraction is an important step in the processes of woody biomass and product generation, replacing alternative costly pre-treatment methods. The hydrolysis of hemicelluloses produces 5-carbon sugars (mainly xylose), 6-carbon sugars (mainly glucose and mannose), and acetic acid. The use of nano-filtration membranes is an efficient technology that can be employed to fractionate hot-water extracts and wood hydrolysate. The residual solid mass after hot-water extraction has a higher energy content and contains fewer easily degradable components. This allows for more efficient subsequent processing to convert cellulose and lignin into conventional products.

Modeling xylan solubilization during autohydrolysis of sugar maple wood meal: reaction kinetics.

Abstract The objective of this work was to study the kinetics of hemicelluloses extraction during hydrothermal pretreatment of sugar maple wood meal. Pretreatment was conducted in a batch reactor at 145–185°C with reaction times up to 8 h and with liquor to solid ratio of 20:1. Under these conditions, hemicelluloses were selectively solubilized and little degradation (approximately 6–9% of the initial amount) of cellulose and lignin was observed. A kinetic model was developed. It was supposed that there are no diffusion limitations and that the reaction rate constants have first-order kinetics with Arrhenius-type temperature dependence. The model proposes the formation of xylose directly from wood xylan as well as from xylooligomers formed in the liquid phase by the hydrolysis of xylan. The model is able to correlate satisfactorily experimentally measured yields of residual xylan, xylooligomers, xylose, and furfural obtained during the pretreatment.

Quantitative analysis of sugars in wood hydrolyzates with 1H NMR during the autohydrolysis of hardwoods

The focus of this work was to determine the utility of (1)H NMR spectroscopy in the quantification of sugars resulting from the solubilization of hemicelluloses during the autohydrolysis of hardwoods and the use of this technique to evaluate the kinetics of this process over a range of temperatures and times. Yields of residual xylan, xylooligomers, xylose, glucose, and the degraded products of sugars, i.e., furfural and HMF (5-hydroxymethyl furfural), were determined. The monosaccharide and oligomer contents were quantified with a recently developed high resolution (1)H NMR spectroscopic analysis. This method provided precise measurement of the residual xylan and cellulose remaining in the extracted wood samples and xylose and glucose in the hydrolyzates. NMR was found to exhibit good repeatability and provided carbohydrate compositional results comparable to published methods for sugar maple and aspen woods.

Hot water extracted wood fiber for production of wood plastic composites (WPCs)

Abstract Undebarked ponderosa pine chips were treated by hot water extraction to modify the chemical composition. In the treated pine (TP), the mass was reduced by approximately 20%, and the extract was composed mainly of degradation products of hemicelluloses. Wood flour produced from TP and unextracted chips (untreated pine, UP) was blended with high-density polyethylene (HDPE) and polypropylene (PP) and was extruded into wood plastic composites (WPCs). Formulations for WPCs consisted of 58% pine, 32% plastic, and 10% other additives. WPC based on HDPE+TP and PP+TP absorbed 46–45% less water than did WPC based on HDPE+UP and PP+UP, respectively. Thickness swelling was reduced by 45–59%, respectively, after 2520 h of immersion. The diffusion constant decreased by approximately 36%. Evaluation of mechanical properties in flexure and tension mode indicated improvements in TP-WPC properties, although the data were not statistically significant in all cases. Results showed that debarking of ponderosa pine is not required for WPC production.

The prediction of pulp yield using selected fiber properties

Abstract The present study is dealing with the question how the major yield-controlling components in pulp (i.e.,hemicelluloses and lignin) alter the behavior and/or properties (e.g., dimensions, flexibility, sugar content) of the fibers. The hypothesis should be verified that certain fiber properties can be used as marker for yield information. Pine and maple wood were digested under specific conditions to produce unbleached pulps with two different lignin contents per method. Screened pulps were chemically analyzed using a new NMR technique for carbohydrates, and the fibers were fractionated using a modified Bauer McNett classification. Pulp yields were related to the pulping methods in the sequence: polysulfide>kraft>biokraft>soda. Carbohydrate analysis revealed that the glucose content (glucose method) was related to the pulping yield. Certain fiber properties (fiber width and coarseness measured directly from the screened pulps) also provided close correlations with the pulp yield. The arithmetic average fiber length and width of the R14 Bauer McNett screen was a significant predictor of yield at the 95% confidence level, with a mean error of 0.43%.

Effect of hot water extracted hardwood and softwood chips on particleboard properties

Abstract The affinity of particleboard (PB) to water is one of the main limitations for using PB in moisture-rich environments. PB dimensional stability and durability can be improved by reducing the available hydroxyl groups in wood through hemicellulose removal, for example, by hot water extraction (HWE), which increases wood resistance to moisture uptake. The resulting liquid fraction from HWE is rich in hemicelluloses and can be used for chemicals and fuels, and the solid fraction is less hydrophilic. The objective of this study was to investigate the effects of HWE of softwood chips (conducted at 160°C and 90 min) and hardwood chips (160°C and 120 min) on the properties of PB panels. HWE increased compressibility and reduced springback by 34% and 44% for pine and maple chips, respectively, which positively impacted the PB properties. Water absorption of pine PB panels was lowered by 35% and that of maple PB panels by 30%, while reduction of thickness swelling was lowered by 39% for pine PB and 56% for maple PB after 24 h of immersion in water. The mechanical properties were not significantly affected.

Hot Water Extraction Improves the Characteristics of Willow and Sugar Maple Biomass With Different Amount of Bark

Shrub willows are being developed as a short rotation woody crop (SRWC) that can grow on marginal agricultural land. Willow has a high net energy ratio (energy produced/ fossil fuel energy consumed), low greenhouse gas footprint and high carbohydrate production potential. Willow biomass can be combined with forest biomass, but willow often has a higher proportion of bark that creates challenges because it increases the ash content and decreases the melting point. Hot water extraction is a pretreatment that has been shown to improve the quality of chipped material while producing a marketable stream of byproducts. This study evaluated how the amount of bark (0%, 33%, 66% and 100%) on three willow cultivars and sugar maple impact the output of hot water extraction in terms of mass removal and extract composition, as well as its influence on the heating value, ash and elemental content. The hot water extraction process resulted in ash content up to 50% for sugar maple and willow, but there was variation among the willow varieties. The heating value after hot water extraction was about 5% higher because of the removal of mostly hemicelluloses, which have relatively low heating value. HWE led to significant reductions of calcium, potassium, magnesium and sulfur contents. The hot water extraction provides a fermentable sugar stream and other co-products after multiple separation and treatment steps, and improves the characteristics of willow and sugar maple biomass for combined heat and power. This paper demonstrates how biomass with higher bark content can generate a useable sugar stream while improving the quality of the biomass for combined heat and power by managing its ash content while simultaneously producing other valuable products.