Published 1966 in Stockholm .
Written in EnglishRead online
Includes bibliographical references.
|Statement||[by] Josef Gierer [and] Leif-Åke Smedman.|
|Contributions||Smedman, Leif-Åke, joint author.|
|LC Classifications||SD1 .S896 no. 498, etc.|
|The Physical Object|
|LC Control Number||78416919|
Download The reactions of lignin during sulphate cooking
Of cooking liquor through the surface of the chip, followed by diffusion into the interior. As the chip heats up, lignin chemical reactions start to occur. When chips are being pulped at elevated temperatures, the rate of liquor diffusion into the wood is the rate-determining step.
Gierer, J.; Sundholm, L. The reactions of lignin during bleaching. The cleavage of aryl alkyl ether linkages and the behaviour The reactions of lignin during sulphate cooking book structural elements of the β-aryl ether- and pinoresinol types during bleaching with aqueous solutions of by: Kraft Process.
Kraft pulping is a full chemical pulping method using sodium hydroxide and sodium sulfide at pH ab at –°C (–°F), corresponding to about kPa (psi) steam pressure, for –3h to dissolve much of the lignin of wood fibers.
During a sulfite cook, there are beneficial reactions that delignify the pulp, as well as several unwanted reactions that decompose the cooking chemicals or react with the cellulose and/or the hemicellulose (Annergren et al.; Rydholm ).
In sulfite pulping, the dissolution of lignin is initiated by the sulfonation of lignin, which. Chemical reactions: In kraft pulping process: Lignin reacts with with sodium hydroxide (NaOH) and forms sodium lignate, or Na-lignate; Sodium lignate dissolves in water, and it causes the fibres to seperate ; Na-lignate is also burned in a furnace with sodium sulphate.
merization reactions. Lignin is a large, cross-linked, racemic macromolecule with molecular masses in excess of 10, (Davin and Lewis ). Lignin can be found in the liquor generated during commercial papermaking, which typically involves and reduction of wood (Fujimoto et al.
) to. From the name "sulfate" it might be assumed that sodium sulfate plays a principal part in the chemical reactions during cooking. Actually it has little or no action on the wood, and it is only after it has been reduced to sodium sulfide during the recovery of the alkali from the black liquor that it is effective in the cooking process.
1 CHEMICAL REACTIONS IN KRAFT PULPING IN COOKING The main objective is to facilitate the disintegration of wood into fibrous product. This is achieved by breaking the bonds in the lignin macromolecule. The main chemical reactions in the cooking process can be described as: NaOH + NaS 2 + Wood à Na-org.
+ S-org. + NaHSFile Size: KB. During bleaching, residual lignin depending on the bleaching chemical used reacts and either provide a water soluble compound or a modified lignin which is colorless.
If chlorine based bleaching agents (Cl 2, ClO 2, Na-hypochlorite etc.) are used, lignin-cl are formed and dissolve in water and are removed. In this process lignin goes into the reactions with the cooking liquor chemicals and split into fragment.
These fragments dissolved with the solution and wood disintegrates into fiber. During the kraft pulping process about 80 percent of lignin, 50 percent of hemicelluloses and 10 percent of celluloses are dissolved.
hydrogen sulfide. The lime kiln can also be a potential source of odor, as a similar reaction occurs with residual sodium sulfide in the lime mud. Lesser amounts of hydrogen sulfide are emitted with the noncondensables of offgases from the digesters and multiple-effect Size: KB.
THE CHEMISTRY OF LIGNIN X. LIGNIN FROM OAT STRAW* BY MAX PHILLIPS AND M. GOSS (From the Industrial Farm Products Research Division, Bureau of Chemistry and Soils, United States Department of Agriculture, Washington) (Received for publication Ap ) In a previous communication (1) results of an investigation were.
relevant chemical reactions, such as sulfonation of lignin, dissolution of lignosulfonate, or formation of sulfate, strong acids and carbon dioxide.
Results from capillary electrophoresis measurements in laboratory experiments were used to determine the temporal change of inorganic sulfur components in cooking acid.
SomeFile Size: KB. This is a review of historical and modern literature data on the structure versus properties of wood lignin in view of the concepts developed by the authors based on their own research. Changes in the structure of lignin and related changes in its chemical reactivity during alkaline wood pulping are assessed based on the comparison of the structures of lignin at three kinetically distinct Cited by: 2.
70 Lignin exists naturally in all woody plants and is integrated into the plant cell wall, functioning as a 71 structural and strengthening component. Lignin sulfonates are produced from lignin in the process of 72 sulfite chemical pulping. This process involves cooking softwood chips under pressure in sulfur dioxide.
the lignin are formed during digestion but some condensation reactions (forming carbon- carbon bond) of lignin units take place and larger lignin fragments are formed. During. Lignin Structure and Reactions. Editor(s): Joseph Marton. Volume Formation of Colored Compounds in the Reaction of Lignin Model Compounds with Alkali and Oxygen.
SAMUEL ROTHENBERG and PHILIP LUNER. Chapter 8, pp Formation and Degradation of Biphenyl Structures During Alkaline Oxidation of Phenols with Oxygen. KARL KRATZL. It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials.
structure. In the Kraft cooking process, about 90–95% of the lignin is dissolved into the cooking liquor containing sodium hydroxide and sodium sulfide. In the pulping process, the lignin macromolecules are fractured, the molecular weight is decreased, the lignin is dissolved in. Books at Amazon. The Books homepage helps you explore Earth's Biggest Bookstore without ever leaving the comfort of your couch.
Here you'll find current best sellers in books, new releases in books, deals in books, Kindle eBooks, Audible audiobooks, and so much more. The reaction products of an alkaline treatment of non-phenolic β-Otype lignin model compounds (C6–C2-type) consisting of p-hydroxyphenyl (H), guaiacyl (G), and/or syringyl (S) nuclei were identified and quantified.
This was performed to examine how the type of H, G, or S nucleus affect the reaction product profiles. The major identified and quantified reaction products were phenol Cited by: 2. net reaction in depolymerization of lignin by SH − (Ar = aryl, R = alkyl groups).
One of the main chemical reactions that underpin the kraft process is the scission of ether bonds by the nucleophilic sulfide (S 2−) or bisulfide (HS −) ions. The highest temperature during a cooking cycle is 1 This document is based primarily on a draft CTA provided by DSM Nutritional Products, sulfonated lignin (i.e., lignosulfonate).
This reaction increases the water-solubility of the hydrophobic lignin Calcium lignosulfonate () is intended for use as a carrier for the production of File Size: KB.
The Chemistry of Lignin provides a critical review of the literature published from to This book provides information pertinent to the fundamental aspects of lignin chemistry. Organized into 27 chapters, this book begins with an overview of the derivatives that are prepared for the characterization of the mother Edition: 1.
Sulfite process, sulfite also spelled Sulphite, chemical process for the manufacture of paper pulp that employs an acid bisulfite solution to soften the wood material by removing the lignin from the e cooking liquor used in the process consists of free sulfur dioxide obtained by the burning of sulfur or by the roasting of iron pyrites, dissolved in water at a concentration of.
During most pulping reactions, components other than lignin are simultaneously removed. The character of pulp depends upon the form and amount of energy supplied for accomplishing the separation.
Chemical, mechanical or a combination of the two forms of energy are utilized. The effects of various process parameters such as reaction time, WL/HL ratio, and reaction temperature on lignin depolymerization were investigated using a 2 L Parr reactor under N2.
Sulfites are chemicals that are in some foods, either naturally or as additives. It’s rare, but some people (about 1 inaccording to the FDA) are sensitive to these compounds. Their. oration, all integrated pulp and paper mills involve the same general steps in the manufacture of pulp and paper.
These steps include: 1) raw material preparation (e.g., debarking and chipping); 2) me-chanical and/or chemical separation of the wood fibers [i.e., grinding, refining, or digestion (cook-ing)] to dissolve the lignin and.
spruce kraft lignin but higher for dissolved lignin after oxygen delignification. A method was developed to estimate the free calcium ion concentration in lignin solutions during titration with calcium ions by the use of ion-selective electrodes.
An end point was detected for the reaction between calcium ions and lignin. At calcium. (1) Wood extractives appear to combine with protolignin during storage of pulpwood or sulfate cooking, but have little effect on the color of thiolignin.
(2) The oxdation of lignin during storage of pulpwood makes dominant wave length change to longer wave length Cited by: 2.
In general, the main raw materials of pulp and papermaking industry can be classified into three categories: wood, non-wood, and non-plant (mainly wastepaper), of which non-wood fiber material is an important fiber source in the areas where forest resources are scarce.
Nowadays, in the total pulp consumption of the world, the proportions of wood pulp, wastepaper pulp, and non-wood pulp are 63 Cited by: 2. Lignosulfonates, or sulfonated lignin are water-soluble anionic polyelectrolyte polymers: they are byproducts from the production of wood pulp using sulfite pulping.
Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin. The methylation of lignin is a key reaction for many different purposes, such as increasing the thermal stability and controlling lignin functionality for polymer applications, and increasing the yield of aromatic hydrocarbons during lignin pyrolysis.
Methylation most often requires the use of toxic reagents, such as dimethyl : Antoine Duval, Luc Avérous. The Formation Of Ferrous Sulfide In Cooked Eggs When an egg has been cooked in hot water for 15 minutes or longer a dark greenish color may be formed on the surface of the egg yolk. If the egg is immersed in cold water immediately after cooking, the green color is not produced or is less apparent than when the egg is left in the hot water to.
Revisiting the mechanism of beta-O-4 bond cleavage during acidolysis of lignin. Part 3: Search for the rate-determining step of a non-phenolic C6-C3 type model compound Hiroaki Ito. In this process, the reagent replaced is sodium sulfate, although the real agent that acts during the delignification reaction is the sulfur that is generated.
The process can be divided into two parts: the first is the production of the pulp and the second is the recovery of the chemicals used [ 8 ].Cited by: 2.
Lignin forms the woody cell walls of plants and the cement material between the plant walls, and after cellulose, it is the second most abundant biopolymer in the world. This book examines the biochemistry of lignin formation, lignin modification and utilization as a polymer, lignin in pulping and bleaching, chemical and physical properties of lignin, and lignin biodegradation.
In trees, lignin helps bind cellulose fibres together, keeping the wood stiff; it’s also responsible for old paper’s yellowing with age, as oxidation reactions cause it to break down into acids, which then help break down cellulose.
‘Old book smell’ is derived from this chemical degradation. fibers during the cooking process in the digester. Sodium Sulfate (Na2SO4) (Salt Cake) - This is a make-up chemical introduced in the recovery boiler and is carried through the recausticizing system and liquor cycle as dead load.
There are other chemicals such as sodium sulfite (Na2SO3), sodium thiosulphate (Na2S2O3), iron, manganese, silica, and. The lignin content was strongly decreased from around 25 % to less than 3 %.
1a Zhu et al. removed the lignin from wood by cooking in NaOH and Na 2 SO 3 solution, followed by hydrogen peroxide (H 2 O 2) treatment, resulting in lignin content less than 3 %.
1b Although considered critical in previous publications, delignification processes are Cited by: Sulfonation and Sulfation Processes Norman C. Foster, Ph.D., P.E. Introduction Sulfonation and sulfation are major industrial chemical processes used to make a diverse range of products, including dyes and color intensifiers, pigments, medicinals, pesticides and organic intermediates.
Additionally, almostmetric tons per year of ligninFile Size: KB. Lignin for chemical recovery in Kraft pulping process. Wood pulp industry provides cellulose fiber for paper and paper board commodity.
In a survey by The Food and Agriculture Organization of the United Nations, the total capacity of dry wood pulp in the US has b – 54, million tons between years – 5 As the side stream, lignin has been generated at Cited by: 8.