scholarly journals Alkali consumption of aliphatic carboxylic acids during alkaline pulping of wood and nonwood feedstocks

Holzforschung ◽  
2013 ◽  
Vol 67 (6) ◽  
pp. 643-650 ◽  
Author(s):  
Hannu Pakkanen ◽  
Raimo Alén
Keyword(s):  
Wheat Straw ◽  
Degradation Products ◽  
Dicarboxylic Acids ◽  
Kraft Pulping ◽  
Alkaline Pulping ◽  
Carbohydrate Degradation ◽  
Cooking Temperature ◽  
Alkali Consumption ◽  
Aliphatic Carboxylic Acids ◽  
Acetic Acids

Abstract The carbohydrate degradation products have been examined, which are formed during the conventional kraft pulping of a softwood, hardwoods, bamboo, and wheat straw as well as soda and soda-anthraquinone pulping of wheat straw. The focus was on “volatile” acids such as formic and acetic acids and “nonvolatile” hydroxy monocarboxylic and dicarboxylic acids. The different consumption profiles were obtained for the charged alkali required for the neutralization of these aliphatic acids depending on the feedstock and the cooking method. The relative composition of the acid fraction in the black liquors of softwood and hardwood and nonwood feedstocks showed characteristic variations. However, in the case of wood kraft pulping, the variations in cooking conditions (effective alkali 19–21% and cooking temperature 155–170°C) had no significant effect on the acid composition. The total amount of volatile and hydroxy acids formed during pulping at a typical target κ number level for each feedstock ranged from 78 to 174 kg ton-1 based on o.d. feedstock. It was highest in birch kraft pulping and lowest in wheat soda-anthraquinone pulping.

Characterization of dissolved material during the initial phase of softwood kraft pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 37-43 ◽  
Author(s):  
HANNU PAKKANEN ◽  
TEEMU PALOHEIMO ◽  
RAIMO ALÉN
Keyword(s):  
Mass Transfer ◽  
Molecular Mass ◽  
Initial Phase ◽  
Degradation Products ◽  
Kraft Pulping ◽  
Reaction Products ◽  
Cooking Temperature ◽  
Molecular Masses ◽  
Aliphatic Carboxylic Acids

The influence of various cooking parameters, such as effective alkali, cooking temperature, and cooking time on the formation of high molecular mass lignin-derived and low molecular mass carbohydrates-derived (aliphatic carboxylic acids) degradation products, mainly during the initial phase of softwood kraft pulping was studied. In addition, the mass transfer of all of these degradation products was clarified based on their concentrations in the cooking liquor inside and outside of the chips. The results indicated that the degradation of the major hemicellulose component, galactoglucomannan, typically was dependent on temperature, and the maximum degradation amount was about 60%. In addition, about 60 min at 284°F (140°C) was needed for leveling off the concentrations of the characteristic reaction products (3,4-dideoxy-pentonic and glucoisosaccharinic acids) between these cooking liquors. Compared with low molecular mass aliphatic acids, the mass transfer of soluble lignin fragments with much higher molecular masses was clearly slower.

The balance between alkali diffusion and alkali consuming reactions during impregnation of softwood. Impregnation for kraft pulping revisited

Holzforschung ◽  
2018 ◽  
Vol 72 (3) ◽  
pp. 169-178 ◽  
Author(s):  
Elisabet Brännvall ◽  
Anders Reimann
Keyword(s):  
Degradation Products ◽  
Kraft Pulping ◽  
Alkali Concentration ◽  
Yield Losses ◽  
Degradation Reactions ◽  
Carbohydrate Degradation ◽  
Alkali Consumption ◽  
High Level ◽  
Short Time ◽  
Time Lead

AbstractThe purpose of the impregnation stage is to ensure that cooking chemicals reach all parts of the chips. However, as alkali comes into contact with wood, reactions take place, which alter the paths available for ionic transport and dissolve wood components. The aim of the present study is to establish the most favorable impregnation conditions, which result in an even alkali concentration profile through the chip at a sufficiently high level without extensive yield losses due to peeling. Softwood chips were subjected to different impregnation conditions. The progress of impregnation was assessed by analyzing the concentration of hydroxide ions in the bound liquor inside wood chips and the release of acetic acid. The extent of undesired reactions was measured as the amount of carbohydrate degradation products formed and amount of wood dissolved. Increased temperature and time lead to more degradation of the carbohydrates during impregnation. At high temperature, the concentration of alkali in the bound liquor was lower due to higher alkali consumption in degradation reactions. The most favorable process is to perform impregnation at an elevated initial effective alkali (EA) for a short time. This resulted in an increased alkali concentration in the bound liquor within the chip without extensive carbohydrate degradation.

Formation of Aliphatic Carboxylic Acids during Soda-AQ Pulping of Kenaf Bark

Holzforschung ◽  
2002 ◽  
Vol 56 (4) ◽  
pp. 388-394 ◽  
Author(s):  
Z. Feng ◽  
R. Alén ◽  
K. Niemelä
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Carboxylic Acids ◽  
Dicarboxylic Acids ◽  
Hydroxy Acids ◽  
Hydroxy Carboxylic Acids ◽  
Aliphatic Carboxylic Acids ◽  
Cooking Conditions ◽  
Acetic Acids

Summary The formation of aliphatic carboxylic acids during soda-AQ pulping of kenaf bark was studied. In addition to formic and acetic acids, a variety of hydroxy monocarboxylic and dicarboxylic acids were monitored. The results showed that the formation of hydroxy acids and formic acid significantly depend, in contrast to acetic acid, on the cooking conditions employed. Detailed gas chromatographic studies revealed that the most abundant hydroxy carboxylic acids were glucoisosaccharinic, lactic, glycolic, 3-deoxypentonic, 2-hydroxybutanoic, xyloisosaccharinic, 3,4-dideoxypentonic, 2-hydroxyglutaric, and glucoisosaccharinaric acids. The total amount of aliphatic carboxylic acids corresponded to 12–16% of o.d. kenaf bark.

Characterization of degradation products from alkaline wet oxidation of wheat straw

2002 ◽  
Vol 82 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Helene B Klinke ◽  
Birgitte K Ahring ◽  
Anette S Schmidt ◽  
Anne Belinda Thomsen
Keyword(s):  
Wheat Straw ◽  
Degradation Products ◽  
Wet Oxidation

Kinetics of Wheat Straw Delignification in Soda and Kraft Pulping

1998 ◽  
Vol 18 (1) ◽  
pp. 69-82 ◽  
Author(s):  
I. Gonzalo Epelde ◽  
C. T. Lindgren ◽  
M. E. Lindström
Keyword(s):  
Wheat Straw ◽  
Kraft Pulping ◽  
Kinetics Of

Investigation of acid hydrolysis for carbohydrate analysis in kraft black liquor

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Silvia Maitz ◽  
Marlene Kienberger
Keyword(s):  
Acid Hydrolysis ◽  
High Performance ◽  
Degradation Products ◽  
Black Liquor ◽  
Amperometric Detection ◽  
Kraft Process ◽  
Kraft Black Liquor ◽  
Carbohydrate Degradation ◽  
Reliable Detection ◽  
Hydrolysis Of

Abstract Black liquor (BL) from the kraft process is considered a promising feedstock for several biorefinery scenarios. Besides lignin and carboxylic acids, this liquor also contains hemicelluloses and their degradation products. A simple and reliable detection of those is of importance for further processing of the liquor. The present paper presents a thorough investigation of quantitative analysis of carbohydrates, by performing acid hydrolysis experiments with a concentrated BL sample of 44% total dry solids. The hydrolysates were then analysed for the four monosaccharides arabinose, xylose, galactose and glucose, by high performance ion chromatography (HPIC) with pulsed amperometric detection. The amount of sulphuric acid needed for complete hydrolysis of the carbohydrates was determined in the range of 3.5–5 mol kg−1 of BL. A lower acid concentration led to insufficient liberation of galactose and glucose, while higher acid concentrations led to degradation of arabinose and xylose. The carbohydrate degradation was also investigated over time for different dilutions and hydrolysis temperatures. These experiments confirmed that the hexoses require considerably harsher conditions for complete liberation compared to xylose and arabinose. The use of internal recovery standards (RSs) was tested; the highest recoveries were obtained by direct spiking of the samples with the RS prior to hydrolysis.

scholarly journals Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

2012 ◽  
Vol 36 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
María Graciela Aguayo ◽  
Regis Teixeira Mendonça ◽  
Paulina Martínez ◽  
Jaime Rodríguez ◽  
Miguel Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Lignin Content ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Pulp Yield ◽  
Chemical Characteristics ◽  
Kraft Pulps ◽  
Opposite Wood ◽  
Alkali Consumption ◽  
Pulp Strength

Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EO)D1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.

Lignocellulose degradation by Fusarium species

1983 ◽  
Vol 61 (4) ◽  
pp. 1194-1198 ◽  
Author(s):  
John B. Sutherland ◽  
Anthony L. Pometto III ◽  
Don L. Crawford
Keyword(s):  
Wheat Straw ◽  
Degradation Products ◽  
Fusarium Species ◽  
Water Soluble ◽  
Lignocellulose Degradation ◽  
Blue Spruce ◽  
Picea Pungens ◽  
Weight Losses ◽  
Aromatic Degradation ◽  
Different Strains

Eighteen strains of fungi in the genus Fusarium, including varieties of F. episphaeria, F. lateritium, F. moniliforme, F. nivale, F. oxysporum, F. rigidiusculum, F. roseum, F. solani, and F. tricinctum, slowly degraded lignocelluloses from blue spruce (Picea pungens) and wheat (Triticum aestivum). When grown with [lignin-14C]lignocellulose from blue spruce, 15 of the Fusarium strains converted 2.2 to 4.3% of the [14C]lignin in 60 days to 14CO2 and 3.9 to 8.4% to labeled water-soluble products. When grown with unlabeled lignocellulose from wheat straw, the strains caused total weight losses in 60 days of 7 to 25%, acid-insoluble (Klason) lignin losses of 2 to 17%, and carbohydrate losses of 3 to 33%. Crude protein contents of degraded wheat-straw lignocellulose samples were 3.2 to 5.1%. Among the aromatic degradation products from wheat-straw lignocellulose degraded by different strains, as shown by gas chromatography, were p-coumaric acid, vanillic acid, vanillin, syringaldehyde, and p-hydroxybenzaldehyde.

scholarly journals Strecker degradation products of aspartic and glutamic acids and their amides

2013 ◽  
Vol 19 (No. 2) ◽  
pp. 41-45 ◽  
Author(s):  
J. Rössner ◽  
J. Velíšek ◽  
F. Pudil ◽  
J. Davídek
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Degradation Products ◽  
Dicarboxylic Acids ◽  
Reaction Products ◽  
Degradation Reactions ◽  
Strecker Aldehydes ◽  
Volatile Products ◽  
Acid Acid

Aspartic and glutamic acids, asparagine and glutamine were oxidised with either potassium peroxodisulphate or glyoxal. Nonvolatile products were derivatised and analysed by GC/FID and GC/MS. Volatile reaction products were isolated and analysed by the same methods. It was found that the degradation reactions of amino acids are complex. Amino acids are principally degraded via the corresponding a-keto acids to Strecker aldehydes (aspartic acid to oxalacetic and 3-oxopropionic acids and glutamic acid to a-ketoglutaric and 4-oxobutyric acids), which are unstable and decomposed by decarboxylation to the corresponding aldehydes. Aspartic acid also eliminates ammonia and yields fumaric acid whereas glutamic acid gives rise to an imine, pyroglutamic acid. A recombination of free radicals leads to dicarboxylic acids (succinic acid from aspartic acid, succinic, glutaric and adipic acids from glutamic acid). The major volatile products (besides the aldehydes) are lower carboxylic acids (acetic acid from aspartic acid and propionic acid acid from glutamic acid) that can at least partly arise by radical reactions. In both quality and quantity terms, a higher amount of degradation products arises by oxidation of amino acids by peroxodisulphate.

MEA/water/AQ-pulping of wheat straw

Holzforschung ◽  
2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Sahab Hedjazi ◽  
Othar Kordsachia ◽  
Rudolf Patt ◽  
Andreas Kreipl
Keyword(s):  
Wheat Straw ◽  
Total Yield ◽  
Strength Properties ◽  
Kappa Number ◽  
Chemical Recovery ◽  
Oxygen Delignification ◽  
Cooking Temperature ◽  
Recovery System ◽  
Environmentally Sound ◽  
High Yields

Abstract Annual plant pulping is faced with serious challenges. Traditional pulping processes with bleaching in chlorine based sequences and without appropriate chemical recovery system cannot be tolerated anymore. Alternative pulping processes with non-conventional chemicals, such as organic solvents, e.g., monoethanolamine (MEA), might be suited for an environmentally sound process with a closed mill system. Thus, pulping of wheat straw with MEA as the main delignifying agent was investigated in comparison to soda and soda/AQ pulps as references. The main focus was placed on reduction of the cooking temperature in order to avoid heat-induced MEA degradation. The temperature was reduced stepwise from 165°C to 130°C. At 150°C, a sufficient delignification was achieved. MEA was partly substituted by water and the resulting decrease of the delignification rate could be compensated by addition of anthraquinone (AQ). After optimization of the process, a pulp with a kappa number of 17 was obtained at a total yield of 56% based on o.d. straw. This pulp was selected for bleaching. Both, O/Q/OP/DQ/P (“ECF light”) and O/Q/OP/ZQ/P (TCFZ) bleaching were applied. NaOH was substituted by MEA as alkali source in the oxygen delignification stage. Up to 50% delignification rate was achieved under these moderate conditions. In the ECF light bleaching sequence, a brightness of 80% ISO was reached at a kappa number level below 3. In TCFZ bleaching, an even somewhat higher brightness was achieved at a kappa number level below 1. A yield of fully bleached screened pulp of around 50% (based on o.d. straw) was obtained. The strength properties of the MEA pulp were improved after bleaching. ECF bleaching resulted in slightly better pulp strengths than the TCFZ alternative. MEA forms in combination with water and AQ a very selective pulping system providing effective delignification and maintaining extremely high yields. MEA/water/AQ pulping should be regarded as a serious, environmentally friendly alternative to soda or soda/AQ pulping to produce high-quality pulp from wheat straw.

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