Eero Sjöström

Analytical methods in wood chemistry, pulping, and papermaking

1 Chemical Composition of Wood and Pulps: Basic Constituents and Their Distribution.- 2 Separation and Analysis of Wood Constituents with Respect to Their Morphological Location.- 3 Carbohydrates.- 4 Lignin.- 5 Extractives.- 6 Direct Characterization of Chemical Properties of Fibers.- 7 Characterization of Pulping Liquors.- 8 Analysis of Bleach Liquors.- 9 Analysis of Papermaking Process Waters and Effluents.- 10 Analysis of Inorganic Constituents.

The Formation of Carboxylic Acids during Kraft and Kraft-Anthraquinone Pulping of Birch Wood

The formation of carboxylic acids was followed during kraft and kraft-anthraquinone (AQ) pulping of birch wood. In all 26 hydroxy monocarboxylic acids and 16 dicarboxylic acids were identified in addition to acetic and formic acids. Their total amount corresponded to 20% (kraft pulping) and 18% (kraft-AQ pulping) of the wood weight. Five of these acids have not earlier been detected in the black liquors. Acetic acid was formed rapidly at the initial stage of pulping, whereas the amounts of the other acids increased continuously without any distinct culmination period. In the presence of AQ the formation of lactic, 2-hydroxybutanoic and isosaccharinic acids was depressed, whereas increased amounts were recorded for glycolic, 3-deoxytetronic and 3-deoxypentonic acids.

Carbohydrate degradation products from alkaline treatment of biomass

Abstract Carbohydrate-rich materials including wood and agricultural residues are degraded by alkali at elevated temperatures into complex mixtures of aliphatic carboxylic acids. The possibilities for the recovery and utilization of the main fraction (hydroxy carboxylic acids) are discussed on the basis of recent literature and unpublished results with reference to some important waste materials (bagasse, rye straw, and pulping liquors) as potential feedstocks.

Alkaline degradation of alginates to carboxylic acids

Abstract Various dicarboxylic acids related to saccharinic acids, as well as several monocarboxylic acids, formed on treatment of alginates with alkali at 95° and 135° have been identified by capillary g.l.c.-m.s. Higher concentrations of alkali facilitated the formation of glucoisosaccharinaric, anhydroisosaccharinaric, and 2-deoxy-3-C-methyltetraric acids, whereas 2,3-dideoxypentaric acid was the major product at lower concentrations. The presence of Ca2+ promoted the formation of α-glucoisosaccharinaric, 3,4-dideoxyhexaric, and 2-hydroxybutanoic acids, especially at 135°. The nature of the reaction products indicates that the alginate chains are degraded end-wise either directly or after cleavage of internal linkages.

Kinetics of alkali-catalyzed isomerization of D-glucose and D-fructose in ethanol-water solutions

Abstract The kinetics of the alkaline isomerization of D -glucose and D -fructose in 0.1 M ethanol-water solutions of sodium hydroxide were studied. To calculate the hydroxylion-independent rate-constants, the ionization equilibria of the respective sugar were determined separately by potentiometric titration in the same solvent system at 21°. The sugars ( D -glucose and D -fructose) in the reaction mixture were analyzed by g.l.c. as the trimethylsilylated oximes. By the micro-scale technique developed, reliable data could be obtained for reactions shorter than 10 seconds. The isomerization of D -glucose to D -fructose, and vice versa , accelerated markedly as a function of the alcohol concentration, and in 70% ethanol, their rates were 2.4 and 1.7 times the corresponding values in water solution. The activation energies of these isomerization reactions were found to be 122 kJ.mol −1 ( D -glucose) and 112 kJ.mol −1 ( D -fructose), and they were independent of the ethanol concentration.

Non-oxidative and oxidative degradation of d-galacturonic acid with alkali

Abstract Degradation products from non-oxidative and oxidative treatment of d -galacturonic acid with alkali have been analysed by g.l.c.-m.s.; 13 hydroxy monocarboxylic acids and 26 dicarboxylic acids were identified in addition to several isomerisation products. In the absence of oxygen, the main degradation products were 3-deoxy- lyxo -hexaric, 3-deoxy- xylo -hexaric, malic, tartonic, C -methyltartronic, lactic, and 3-deoxytetronic acids. In the presence of oxygen, arabinaric, threaric, malic, tartronic, and glycolic acids were formed in large proportions. The routes of formation for most of the compounds are outlined.

Non-oxidative and oxidative alkaline degradation of pectic acid

Abstract As alkaline degradation products of pectic acid, 6 hydroxymonocarboxylic, 16 dicarboxylic, and 2 tricarboxylic acids were identified by g.l.c.-m.s. as their trimethylsilyl derivatives. In the absence of oxygen, the most abundant degradation products are 3-deoxy-2-C-(hydroxymethyl)pentaric, 2,3-dideoxypentaric, 2-deoxy-3-C-methyltetraric, malic, and 21,4-anhydro-3-deoxy-2-C-(hydroxymethyl)pentaric acids, whereas, in the presence of oxygen, glycolic, oxalic, malic, 3-deoxypentaric, and 2-C-carboxy-3-deoxypentaric acids preponderate. The routes of formation of these acids show many similarities with those encountered in the alkaline degradation of cellulose.

Identification of the products of hydrolysis of carboxymethylcellulose

Abstract Hydrolysis of carboxymethylcelluloses, made from softwood and hardwood pulps, gave mainly glucose and its mono- and di-substituted derivatives, together with considerable amounts of products derived from hemicellulose constituents. Each hydrolysate contained 2- and 3- O -carboxymethylxylose; mono- and di-substituted mannose derivatives were also detected after hydrolysis of the carboxymethylated softwood pulp. 2,3,6-Tri- O -carboxymethyl derivatives of glucose and mannose were detected in hydrolysates of samples of higher degrees of substitution, and 2,3-di- O -carboxymethylxylose was found only after hydrolysis of hardwood-derived samples.

Oxidative Pretreatment of Pine Wood Prior to Alkaline Pulping Part II. Characterization of Lignin by Spectroscopic Methods

Etude de la structure chimique de la lignine de Pinus sylvestris apres un pretraitement par O 2 en milieu alcalin (spectrometries UV, IR et RMN)

The Effect of Solvent oh the Oxygen Oxidation of Polysaccharides

Abstract The extent to which oxygen can stabilize polysaccharides against alkaline degradation was studied. The conversion of aldehyde end groups to aldonic acid groups mainly arabinonic and erythronic acids) was accelerated markedly when cellobiose, hydro-cellulose, or wood chips were treated in aqueous alkali with oxygen in the presence of anthraquinone monosulfonate. Change of the solvent to aqueous ethanol gave an even more pronounced effect without any additive. Other alcohols (methanol, n-propanol, n-hexanol, and ethylene glycol) gave a similar effect. After an oxidative pretreatment, the alkali stability of hydrocellulose (at 100 C) was increased from about 50 % to more than 90 %. When the pretreated chips were pulped in soda-AQ liquor, the rate of delignification was substantially increased. The effect of oxidation on the stabilization of wood polysaccharides, however, was small because of the low stability of the aldonic acid end groups formed at higher temperatures.