Genetic Engineering of Poplar Lignins: Impact of Lignin Alteration on Kraft Pulping Performances

Brownstock washing is a complex, dynamic process in which dirty wash water or weak black liquor (dissolved organic and inorganic material obtained from the pulp cooking process) is separated from pulp fibers. The use of material balance techniques is of great importance to identify potential problems and determine how well the system is operating. The kraft pulping industry was the first known to combine pulp washing with the recovery of materials used and produced in the wood cooking process. The motivation behind materials recovery is economic, and more recently, environmentally driven. The chemicals used in the kraft process are expensive as compared to those used in the sulfite process. For the kraft process to be economically viable, it is imperative that a very high percentage of the cooking chemicals be recovered. To reach such high efficiency, a variety of washing systems and monitoring parameters have been developed. Antifoam additives and processing aids have also played an important role in increasing washing effectiveness. Antifoam materials help attain washing effectiveness by preventing entrapped air from forming in the system, which allows for an easier, unimpeded flow of filtrate through the screens and washers.

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Co-cooking nonwoods with hardwoods

TAPPI Journal ◽

10.32964/tj13.6.19 ◽

2014 ◽

Vol 13 (6) ◽

pp. 19-24

Author(s):

TROY RUNGE ◽

CHUNHUI ZHANG

Keyword(s):

High Performance Liquid Chromatography ◽

High Performance ◽

Paper Industry ◽

Pulp And Paper Industry ◽

Strength Properties ◽

Agricultural Residues ◽

Kraft Pulping ◽

Pulp And Paper ◽

Strength Increase ◽

Xylan Content

Agricultural residues and energy crops are promising resources that can be utilized in the pulp and paper industry. This study examines the potential of co-cooking nonwood materials with hardwoods as means to incorporate nonwood material into a paper furnish. Specifically, miscanthus, switchgrass, and corn stover were substituted for poplar hardwood chips in the amounts of 10 wt %, 20 wt %, and 30 wt %, and the blends were subjected to kraft pulping experiments. The pulps were then bleached with an OD(EP)D sequence and then refined and formed into handsheets to characterize their physical properties. Surprisingly, all three co-cooked pulps showed improved strength properties (up to 35%). Sugar measurement of the pulps by high-performance liquid chromatography suggested that the strength increase correlated with enriched xylan content.

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

TAPPI Journal ◽

10.32964/tj12.1.37 ◽

2013 ◽

Vol 12 (1) ◽

pp. 37-43 ◽

Cited By ~ 1

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.

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