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The cell walls of cereals are rich sources of polysaccharide β-glucan. In this study, the β-glucan was extracted from oat bran using the hot-water extraction method and dried in a pure powder form. The concentration of the β-glucan in the extract was determined using the l-cysteine sulfuric acid method. The results showed that the yield of β-glucan using the hot-water extraction method is the highest compared to its yield achieved by enzymatic, acid, and alkaline methods. In this paper, the usage of the β-glucan as a coating material for a water-insoluble carotenoid is considered. This study demonstrates for the first time the encapsulation of β-carotene with modified octanoic acid β-glucan. It implements to obtain a stable encapsulated polysaccharide-carotenoid system, which has been studied by a set of physicochemical methods and a cytotoxic analysis was performed on the HCT-116 cell line. The SEM image of the resulting encapsulated system is perfectly correlated with the DLS data, which has determined the size of MG capsules at 200 nm. The cytotoxic analysis demonstrates that the cell viability was more than 70%, which indicates its potential using in the food industry. [ABSTRACT FROM AUTHOR]

Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust.

Agricultural residues, such as corn stover, wheat straw, and nut shells show promise as feedstocks for lignocellulosic biorefinery due to their relatively high polysaccharide content and low or no nutritional value for human consumption. Apricot pit shells (APS) were studied in this work to assess their potential for use in a biorefinery. Hot water extraction (HWE; 160 °C, 2 h), proposed to remove easily accessible hemicelluloses, was performed to evaluate the susceptibility of APS to this mild pretreatment process. The chemical composition of APS before and after HWE (EAPS) was analyzed by standard methods and 1H-NMR. A low yield of the remaining HW-extracted APS (~59%) indicated that APS are highly susceptible to this pretreatment method. 1H-NMR analysis of EAPS revealed that ~77% of xylan present in raw APS was removed along with ~24% of lignin. The energy of combustion of APS was measured before and after HWE showing a slight increase due to HWE (1.61% increase). Near infrared radiation spectroscopy (NIRS), proposed as a quick non-invasive method of biomass analysis, was performed. NIRS corroborated results of traditional analysis and 1H-NMR. Determination of antioxidizing activity (AOA) of APS extracts was also undertaken. AOA of organic APS extracts were shown to be more than 20 times higher than that of a synthetic antioxidizing agent.

Lignin recovered from the hot-water extract of sugar maple (Acer saccharum) is used in this study to synthesize adhesive blends to replace phenol-formaldehyde (PF) resin. Untreated lignin is characterized by lignin content and nuclear magnetic resonance (NMR) analysis. The molecular weight distribution of the lignin and the blends are characterized by size exclusion chromatography (SEC). The effect of pH (0.3, 0.65 and 1), ex situ furfural, and curing conditions on the tensile properties of adhesive reinforced glass fibers is determined and compared to the reinforcement level of commercially available PF resin. The adhesive blend prepared at pH = 0.65 with no added furfural exhibits the highest tensile properties and meets 90% of the PF tensile strength.

Hot water extraction of aspen woodchips was treated at about 160 °C for 2 h with a liquor-to-solid ratio of 4.76:1 in a 1.84 m3 batch reactor with external liquor circulation. Both five-carbon and six-carbon sugars are obtained in the extraction liquor. Xylose and xylooligomers are the main five-carbon sugar in the hot water extract, which reached a maximum concentration of 0.016 mol/L, and 0.018 mol/L, respectively. Minor monosaccharides including galactose, mannose, rhamnose, glucose, and arabinose are also obtained during the hot water extraction. Rhamnose is the main six-carbon sugar in the extraction liquor, which has a maximum concentration of 0.0042 mol/L. The variations of acetyl groups and formic acid are investigated due to their catalytic effect on the extraction reactions. Zeroth-order kinetics models are found to be adequate in describing the dissolved solids, acids, xylose, and xylooligomers.

Abstract The thermochemical behavior of various samples of okra (Abelmoschus esculentus) and miscanthus (Miscanthus x giganteus) stalks (initial, hot-water-extracted, and those from sulfur-free delignification) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In all cases, major GC-amenable condensable products were measured semi-quantitatively and classified into several product groups. The formation of these product groups from different feedstock samples with varying mass portions of their structural constituents (carbohydrates and lignin) was investigated at 500 °C and 700 °C with a residence time of 5 s and 20 s. The main product groups were aliphatic compounds, such as lactone, furan, and cyclopentenone derivatives from carbohydrates (mainly hemicelluloses) and aromatic compounds, such as guaiacol, phenol, and syringol derivatives from lignin. Additionally, the formation of aliphatic and aromatic products (e.g., the ratio of aliphatic compounds to aromatic compounds) was found to be characteristically dependent on feedstock composition and pyrolysis conditions. This kind of approach is of practical importance concerning efforts not only to uncover new integrated biorefinery possibilities to manufacture value-added products but also to develop rapid characterization tools for lignocellulosics. Highlights • Solid organic fractions from hot-water-extraction of targeted non-wood feedstocks were pyrolyzed. • Fast pyrolysis has been utilized in the integrated biorefinery concept. • The ratio aliphatic/aromatic pyrolysis compounds characteristically depends on feedstock composition and pyrolysis conditions. • A basis of a rapid characterization method for lignocellulosics has been developed. [ABSTRACT FROM AUTHOR]

A hardwood-based biorefinery process starting with hot-water extraction (HWE) is recommended in order to remove most of the hemicelluloses/xylans before further processing. HWE may be followed by delignification in acetone/water in the presence of oxygen (AWO) for the production of cellulose and lignin. In this study, the HWE-AWO sequence was evaluated for its effectiveness at removing lignin from the fast-growing species Paulownia tomentosa (PT) and Paulownia elongata (PE), in comparison with the reference species, sugar maple (Acer saccharum, SM). HWE might lead to a remarkable increase in lignin accessibility, and as a result, a greater AWO delignification degree was observed for extracted PT, PE, and SM than for unextracted ones. Organosolv lignin was recovered from the spent liquor of AWO delignification of PT with/without prior HWE and characterized to evaluate the benefits of HWE on the lignin structure and purity. The lignin recovered from the spent liquor of HWE-AWO sequence is of higher purity and lighter color than that recovered from the AWO spent liquor. These properties along with low sulfur content are desirable for lignin high-value applications.

The thermochemical behavior of birch ( Betula pendula ) sawdust both untreated and after various chemical treatments (hot-water extraction, delignification, and hot-water extraction followed by delignification) was investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). In each case, major GC-amenable condensable products were classified into several compound groups, and the formation of these monomer-related fragments from feedstock samples with varying mass portions of the structural constituents (cellulose, hemicelluloses, and lignin) were determined at 500 °C and 700 °C at hold times of 5 s and 20 s. The formation of pyrolysis products was shown to be characteristically dependent on feedstock composition as well as on pyrolysis conditions. This kind of approach was of practical importance with respect to efforts not only to develop rapid characterization tools for lignocellulosics, but also to new biorefinery possibilities to produce bio-oils, for example, enriched either with aliphatic or aromatic constituents. [ABSTRACT FROM AUTHOR]

Moso bamboo (Phyllostachys edulis) is one of the widely growing bamboo species in Asia. Because of its fast growth and aggressive rhizomes, it is reported to invade other forests and reduce the biodiversity of forest ecosystems. To determine the changes in soil nutrient conditions due to moso bamboo invasion, this research measured the difference in soil labile carbon (C) and nitrogen (N) contents in a Japanese cedar (Cryptomeria japonica) forest invaded by moso bamboo in central Taiwan. The content of soluble organic C (SbOC), measured by both KCl and hot-water extraction methods, was lower in bamboo than cedar soils. This observation agreed with the finding that the more easily decomposed SbOC could be lost with bamboo invasion. In addition, both SbOCKCl and SbOCHW contents were positively correlated with microbial biomass C content, so the decreased labile organic C content in bamboo soils may reduce microbial biomass production. Principal component analysis revealed soil organic C content (total organic C, SbOC and acid-hydrolysable C) as the most important soil parameter affected by the bamboo invasion, followed by microbial biomass N and NO3 􀀀 contents in soils. The soil quality index model also agreed with the degraded soil quality with bamboo invasion. In conclusion, the invasion of moso bamboo reduced the C and N pools in bamboo soil and degraded the overall soil quality. [ABSTRACT FROM AUTHOR]

It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama., Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a regional network of forest dynamics plots. Experimental manipulation of boron supply to seedlings of three tropical tree species revealed no evidence of boron deficiency or toxicity at concentrations likely to occur in tropical forest soils. Foliar boron did not correlate with soil boron along a local scale gradient of boron availability., Fifteen years of boron addition to a tropical forest increased plant-available boron by 70% but did not significantly change tree productivity or boron concentrations in live leaves, wood or leaf litter. The annual input of boron in rainfall accounts for a considerable proportion of the boron in annual litterfall and is similar to the pool of plant-available boron in the soil, and is therefore sufficient to preclude boron deficiency., We conclude that boron does not influence tree species distributions in Panama and presumably elsewhere in the lowland tropics. [ABSTRACT FROM AUTHOR]

Hot-water extraction of hemicelluloses, especially galactoglucomannans, from fractions of ground spruce wood with different particle sizes was studied at 170°C with extraction times up to 60 min. Extraction of spruce sapwood, heartwood, and thermomechanical pulp (TMP) was also compared at 160 to 180°C. Static batch extractions were carried out in an accelerated solvent extractor (ASE). The extracted hemicelluloses were characterized by sugar unit analysis and determination of acetyl groups and molar masses. The particle size significantly affected the extraction of ground wood. The total extraction yield, as well as the yields of hemicelluloses and monosaccharides, was the highest from the finest ground wood fraction (< 0.1 mm). The release of acetic acid, average molar mass of extracted hemicelluloses, and end-pH of the extracts were also dependent of the particle size, although to a lower extent. Irrespectively of the ground wood particle size, the yield of hemicelluloses reached a plateau after 40 min extraction at 170°C. The results indicate that extraction of hemicelluloses is limited mainly by the diffusion in the fiber wall, and for coarse wood shives also by the mass transfer in the wood matrix. There were only small differences in the hot-water extraction yields of hemicelluloses from spruce sapwood, heartwood, and TMP, considering both poly- and monosaccharides.

Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust. [ABSTRACT FROM AUTHOR]

Miscanthus (Miscanthus sp. Family: Poaceae) was hot-water extracted (two h, at 160 °C) at three scales: laboratory (Parr reactor, 300 cm3), intermediate (M/K digester, 4000 cm3), and pilot (65 ft3-digester, 1.841 × 106 cm3). Hot-water extracted miscanthus, hydrolyzate, and lignin recovered from hydrolyzate were characterized and evaluated for potential uses aiming at complete utilization of miscanthus. Effects of scale-up on digester yield, removal of hemicelluloses, deashing, delignification degree, lignin recovery and purity, and cellulose retention were studied. The scale-dependent results demonstrated that before implementation, hot-water extraction (HWE) should be evaluated on a scale larger than a laboratory scale. The production of energy-enriched fuel pellets from hot-water extracted miscanthus, especially in combination with recovered lignin is recommended, as energy of combustion increased gradually from native to hot-water extracted miscanthus to recovered lignin. The native and pilot-scale hot-water extracted miscanthus samples were also subjected to enzymatic hydrolysis using a cellulase-hemicellulase cocktail, to produce fermentable sugars. Hot-water extracted biomass released higher amount of glucose and xylose verifying benefits of HWE as an effective pretreatment for xylan-rich lignocellulosics. The recovered lignin was used to prepare a formaldehyde-free alternative to phenol-formaldehyde resins and as an antioxidant. Promising results were obtained for these lignin valorization pathways.

Agricultural residues, such as corn stover, wheat straw, and nut shells show promise as feedstocks for lignocellulosic biorefinery due to their relatively high polysaccharide content and low or no nutritional value for human consumption. Apricot pit shells (APS) were studied in this work to assess their potential for use in a biorefinery. Hot water extraction (HWE; 160 °C, 2 h), proposed to remove easily accessible hemicelluloses, was performed to evaluate the susceptibility of APS to this mild pretreatment process. The chemical composition of APS before and after HWE (EAPS) was analyzed by standard methods and 1H-NMR. A low yield of the remaining HW-extracted APS (~59%) indicated that APS are highly susceptible to this pretreatment method. 1H-NMR analysis of EAPS revealed that ~77% of xylan present in raw APS was removed along with ~24% of lignin. The energy of combustion of APS was measured before and after HWE showing a slight increase due to HWE (1.61% increase). Near infrared radiation spectroscopy (NIRS), proposed as a quick non-invasive method of biomass analysis, was performed. NIRS corroborated results of traditional analysis and 1H-NMR. Determination of antioxidizing activity (AOA) of APS extracts was also undertaken. AOA of organic APS extracts were shown to be more than 20 times higher than that of a synthetic antioxidizing agent. [ABSTRACT FROM AUTHOR]

Lignin recovered from the hot-water extract of sugar maple (Acer saccharum) is used in this study to synthesize adhesive blends to replace phenol-formaldehyde (PF) resin. Untreated lignin is characterized by lignin content and nuclear magnetic resonance (NMR) analysis. The molecular weight distribution of the lignin and the blends are characterized by size exclusion chromatography (SEC). The effect of pH (0.3, 0.65 and 1), ex situ furfural, and curing conditions on the tensile properties of adhesive reinforced glass fibers is determined and compared to the reinforcement level of commercially available PF resin. The adhesive blend prepared at pH = 0.65 with no added furfural exhibits the highest tensile properties and meets 90% of the PF tensile strength. [ABSTRACT FROM AUTHOR]

Conversion of woody biomass to chemicals, materials and energy requires at least three steps: pretreatment, cracking and conversion. Size reduction is the minimum required pretreatment step prior to further processing. Cracking step is the middle step in woody biomass conversion whereby solid woody biomass is reduced to small building blocks (molecules) or intermediates. The last step in woody biomass conversion is the generation of desired products from the building blocks or intermediates. Reactions involve woody biomass usually as a solid. The (solid–liquid or solid–gas) surface reactions have an apparent zeroth order owing to the complete renewal of surfaces during the dissolution. A vast array of products (chemicals, energy and materials) can be produced from woody biomass based on its four major components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The pretreatment step is designed to improve the efficiency of the cracking step. Waste products are commonly produced during pretreatment step for a sugar-based biorefinery due in part to the desire to maximize (or degrade cellulose to) glucose production. Non cellulose components in a sugar-based biorefinery were commonly discarded, starting from the pretreatment step. A synergetic approach is to eliminate the waste generation in pretreatment and inserting a step to turn the otherwise waste into value-added product(s). Hot-water extraction can serve this purpose. With a hot-water extraction process as a pretreatment step, size reduction can be enhanced after the high pressure operation. Value-added products can be produced from the hot-water extraction and the treated woody biomass can be more efficiently transformed in the cracking step: either be sugar-based, or gasification, or pyrolysis, or direct conversion to solid wood products. The synergy stems from the selective separation/removal of components from woody biomass. The reaction of solid component dissolutions from the woody biomass is of zeroth order, following a surface renewal mechanism during the bulk of the hot-water extraction process. [ABSTRACT FROM AUTHOR]

Hot-water extraction (HWE) is a biomass processing method that offers an excellent possibility to generate multiple value-added products. In this study, the pellets were produced from the original spruce sawdust and the sawdust after HWE. Two different arrangements to separate the extracted sawdust from the liquid phase (extract) were applied, namely a rapid solid-liquid separation at high temperature and a slow cooling of extracted sawdust along with the extract. Furthermore, the extracted sawdust was also used several times as an adsorbent to purify the extract from the HWE. The effect of binders (kraft lignin and corn starch) on the pellet properties was also evaluated. Fuel properties, mechanical characteristics and chemical composition of produced pellets were analyzed. The HWE improves the mechanical and energy properties by increasing the pellet's length (2–9% increase), particle and energy density (24% and 31% increase correspondingly) in comparison with the untreated sawdust pellets. Additionally, the pellets from the treated sawdust indicated reduced water absorption capacity and improved strength and durability characteristics compared to the untreated ones. The HWE modifies the lignocellulosic matrix of feedstock resulting in more significant modifications than in the case of binder added to the untreated sawdust. The method of residual sawdust separation from the extract had a pronounced effect on the pellet's characteristics, namely a slow cooling of extracted sawdust in mixture with liquid fraction resulted in a smaller amount of hemicelluloses and monosaccharides in the sawdust and more intensive release (up to 70%) of ash forming elements to the liquid phase. Hot-water extraction presents a beneficial path to valorize woody sawdust by producing several valuable streams, such as hemicelluloses, fuel pellet and biochemicals. [Display omitted] • Hot-water extraction (HWE) generates a range of high-value streams from biomass. • HWE improves the mechanical properties and energy content of pellets. • Slow cooling of extracted sawdust with liquid significantly decreased ash content. • The effect of binder addition is more pronounced for untreated sawdust pellets. • Combustion and pyrolysis reactivities of the pellets were slightly affected by HWE. [ABSTRACT FROM AUTHOR]

Integration of biomass pretreatment with pyrolysis offers an opportunity to improve end-product quality and conversion efficiency. In this study, sugar maple ( Acer saccharum ) was subjected to both hot-water extraction (HWE) at 160 °C (at residence times of 0.5 h, 1.0 h, and 2.0 h) and electron beam (EB) irradiation at a dose of 1000 kGy. Pyrolysis studies were then conducted on all the treated samples at 550 °C using a bench scale pyroprobe-gas chromatography–mass spectrometry (Py-GC/MS). The HWE samples were selected for further evaluation in catalytic pyrolysis using HZSM-5 catalysts for the production of aromatic hydrocarbons. Analysis of the hot-water treated sample at 160 °C for 2 h showed that HWE increased the volatile mater and decreased the fixed carbon and ash contents; also the glucan content increased by 24% and the xylan decreased by 54%. Derivative thermogravimetry (DTG) analysis indicated that EB irradiation reduced the crystallinity of the sugar based polymers while HWE solubilized the hemicellulose fraction. The pyrolysis results showed that EB irradiation increased the formation of furanic aldehydes (furfural and 5-hydroxymethylfurfural (5-HMF)) and decreased hydroxyacetaldehyde (HAA) and levoglucosan (LG). By contrast, HWE increased the yield of LG, HAA, 5-HMF and furfural; but, decreased the yields of acetic acid (HAc), hydroxyacetone, and other ketones. For the HWE-2 h sample, LG formation increased from 4.45 wt.% to 11.57 wt.% and HAc decreased from 4.87 wt.% to 2.40 wt.%. Catalytic pyrolysis of HWE samples with HZSM-5 zeolite showed that the carbon yields of monoaromatic hydrocarbons increased. HWE treatment at 160 °C for 2 h increased the yield of benzene by 46%, toluene by 35% and xylene by 26%. Pyrolysis-TGA also indicated that HWE decreased the formation of char/coke. Overall, the reduction in the formation of acids and ketones caused by HWE suggest that it could be used to improve bio-oil quality in non-catalytic pyrolysis whilst the increase in the yield of monoaromatic hydrocarbons indicate that HWE could be used to enhance the carbon efficiency in catalytic pyrolysis. [ABSTRACT FROM AUTHOR]

Abstract: Woody biomass is renewable only if sustainable production is imposed. An optimum and sustainable biomass stand production rate is found to be one with the incremental growth rate at harvest equal to the average overall growth rate. Utilization of woody biomass leads to a sustainable economy. Woody biomass is comprised of at least four components: extractives, hemicellulose, lignin and cellulose. While extractives and hemicellulose are least resistant to chemical and thermal degradation, cellulose is most resistant to chemical, thermal, and biological attack. The difference or heterogeneity in reactivity leads to the recalcitrance of woody biomass at conversion. A selection of processes is presented together as a biorefinery based on incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. A preference is given to a biorefinery absent of pretreatment and detoxification process that produce waste byproducts. While numerous biorefinery approaches are known, a focused review on the integrated studies of water-based biorefinery processes is presented. Hot-water extraction is the first process step to extract value from woody biomass while improving the quality of the remaining solid material. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers, aromatics and acetic acid in the hardwood extract are the major components having the greatest potential value for development. Higher temperature and longer residence time lead to higher mass removal. While high temperature (>200°C) can lead to nearly total dissolution, the amount of sugars present in the extraction liquor decreases rapidly with temperature. Dilute acid hydrolysis of concentrated wood extracts renders the wood extract with monomeric sugars. At higher acid concentration and higher temperature the hydrolysis produced more xylose monomers in a comparatively shorter period of reaction time. Xylose is the most abundant monomeric sugar in the hydrolysate. The other comparatively small amounts of monomeric sugars include arabinose, glucose, rhamnose, mannose and galactose. Acetic acid, formic acid, furfural, HMF and other byproducts are inevitably generated during the acid hydrolysis process. Short reaction time is preferred for the hydrolysis of hot-water wood extracts. Acid hydrolysis presents a perfect opportunity for the removal or separation of aromatic materials from the wood extract/hydrolysate. The hot-water wood extract hydrolysate, after solid-removal, can be purified by Nano-membrane filtration to yield a fermentable sugar stream. Fermentation products such as ethanol can be produced from the sugar stream without a detoxification step. [Copyright &y& Elsevier]

Abstract: The conversion of biomass to chemicals and energy is imperative to sustaining our way of life as known to us today. Fossil chemical and energy sources are traditionally regarded as wastes from a distant past. Petroleum, natural gas, and coal are not being regenerated in a sustainable manner. However, biomass sources such as algae, grasses, bushes and forests are continuously being replenished. Woody biomass represents the most abundant and available biomass source. Woody biomass is a reliably sustainable source of chemicals and energy that could be replenished at a rate consistent with our needs. The biorefinery is a concept describing the collection of processes used to convert biomass to chemicals and energy. Woody biomass presents more challenges than cereal grains for conversion to platform chemicals due to its stereochemical structures. Woody biomass can be thought of as comprised of at least four components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The biorefinery concept proposed at ESF (State University of New York — College of Environmental Science and Forestry) aims at incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. The emphasis of this work is on the kinetics of hot-water extraction, filling the gap in the fundamental understanding, linking engineering developments, and completing the first step in the biorefinery processes. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers and acetic acid in the extract are the major components having the greatest potential value for development. Extraction/hydrolysis involves at least 16 general reactions that could be divided into four categories: adsorption of proton onto woody biomass, hydrolysis reactions on the woody biomass surface, dissolution of soluble substances into the extraction liquor, and hydrolysis and dehydration decomposition in the extraction liquor. The extraction/hydrolysis rates are significantly simplified when the reactivity of all the intermonomer bonds are regarded as identical within each macromolecule, and the overall reactivity are identical for all the extractable macromolecules on the surface. A pseudo-first order extraction rate expression has been derived based on concentrations in monomer units. The reaction rate constant is however lower at the beginning of the extraction than that towards the end of the extraction. Furthermore, the H-factor and/or severity factor can be applied to lump the effects of temperature and residence time on the extraction process, at least for short times. This provides a means to control and optimize the performance of the extraction process effectively. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: A mathematical description is presented for xylan solubilization during hydrothermal pretreatment of sugar maple and aspen wood chips. It assumes first-order kinetics with Arrhenius-type temperature dependence of the reaction rate constants and includes limitations on the transport of reaction products formed in the wood pores to the bulk liquor. The model is calibrated with experimentally measured yields of residual xylan, xylooligomers, and xylose obtained in the autohydrolysis of sugar maple wood chips under pretreatment conditions of 152−175°C, reaction times of 0−6h, and liquor to solid ratio of 6:1 in a batch digester. It is validated against experimental data obtained from the autohydrolysis of aspen wood chips at 160°C under similar experimental conditions as those used for sugar maple. The model can also satisfactorily correlate data of deacetylation of xylan and formation of products (free acetyl groups and acetyl groups attached to xylooligomers in the hydrolyzate) in the autohydrolysis of sugar maple and aspen wood chips with fair accuracy. [Copyright &y& Elsevier]