Southern pineprehydrolyzates: Characterization of polysaccharides and lignin fragments

Abstract

Prehydrolyzates obtained by treatment of southern pine chips at 175° with steam and water were examined in parallet studies. Carbohydrates were separated from other solids and fractionated into monosaccharides, low‐molecular weight polysaccharides and highmolecular weight polysaccharides. The latter fractions were selectively subfractionated into series of glucomannans and galactoglucomannans using barium precipitation. The poly‐saccharide fractions were characterized by gel permeation chromatography (gpc), the hemicellulose subfractions by periodate oxidation, vapor pressure osmometry, polarimetry, and end‐group assay. Sugar ratios were determined on hydrolyzates of all fractions. Water prehydrolysis was shown to remove substantially more carbohydrates from the chips than steam prehydrolysis, 9.3% versus 3.3% (O.D. wood basis), and these carbohydrates had higher average molecular weight, contained more mannose per unit glucose and yielded more galactoglucomannans than those removed by steam. One of the galactoglucomannans from water prehydrolyzate had the highest number average molecular weight in this study: 3100 by end‐group assay, 3800 by osmometry; polysaccharides of even higher molecular weight were indicated by gpc prehumps. Several monomeric lignin degradation products were identified in the methyl ethyl ketone soluble fraction of steam prehydrolyzate. Among these were coniferaldehyde, vanillic acid, vanillin, protocatechualdehyde, phydroxybenozic acid and, unexpectedly, a sizeable proportion of dihydroconiferyl alcohol.

Pulp Mills and Wood-Based Biorefineries

“…[110][111][112][113][114][115][116][117][118][119] The integration of pretreatment with kraft pulping, mainly with respect to pulping performance and pulp properties have also been studied. [110][111][112][113][114][115][116][117][118][119] The integration of pretreatment with kraft pulping, mainly with respect to pulping performance and pulp properties have also been studied.…”

“…[110][111][112][113][114][115][116][117][118][119] The integration of pretreatment with kraft pulping, mainly with respect to pulping performance and pulp properties have also been studied. 111,126 The main chemical utilization of hemicelluloses includes films, surface modifiers, and various derivatives. 111,126 The main chemical utilization of hemicelluloses includes films, surface modifiers, and various derivatives.…”

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, and Pulping Outcomes

“…Depending on the severity of treatment conditions (temperature, treatment time, and pressure), autohydrolysis can result in the formation of mono-, oligo-, and polysaccharides (up to 60 -80% of the total dissolved organics) (Gullón et al 2012;Lehto et al 2014a,b) and dissolved lignin, together with a variety of their degradation products (Sears et al 1971;Nabarlatz et al 2004;Paredes et al 2008;El Hage et al 2010). The benefits of the autohydrolysis process over the acid pretreatments are that corrosion problems are limited, no waste sludges are generated, economic and operational costs are low, and cellulose is not significantly degraded under the applied conditions (Garrote et al 1999a,b;Lei et al 2010;Xiao et al 2011).…”

Integration of (Hemi)-Cellulosic Biofuels Technologies with Chemical Pulp Production

“…In addition to deriving products from hardwoods, autohydrolysis can also generate GGMs from softwoods prior to Kraft pulping, as shown by studies reporting results for industrially important softwoods, including Norway spruce (Picea abies) [123][124][125][126] and loblolly pine (Pinus taeda) [127,128]. Autohydrolysis of loblolly pine prior to Kraft pulping was found to yield up to 120 mg of hemicellulose monomers and water-soluble oligomers per gram of original wood [127], and softwoods may require slightly harsher conditions during autohydrolysis to yield soluble hemicellulose yields comparable to those of hardwoods.…”