Alkaline Pulping of Hemp Woody Core: Kinetic Modelling of Lignin, Xylan and Cellulose Extraction and Degradation

The kinetics of alkaline degradation of lignin, xylan and cellulose in relation to pulp yield were studied for hemp woody core to support development and optimization of a non^polluting alkaline pulping process. Shavings of hemp woody core were impregnated at room temperature with various sodium hydroxide concentration (0.25-2 M NaOH) and delignified isothermally at various reaction temperatures (150-180 °C) in a flow-through reactor. Extraction and degradation of xylan from hemp woody core was strongly depending on the NaOH concentration used. Consequently, to attain a certain lignin content, lower NaOH concentrations result in higher pulp yields. Extended pulping diminished the differences in pulp yields, due to further xylan degradation. The kinetics of lignin, xylan and cellulose degradation were modelled as a function of reaction time, temperature and NaOH concentration. The combined models resulted in a pulp yield model for hemp woody core, suitable for process optimization purposes. Degradation kinetics of perennial wood can be modelled similarly, which was illustrated using literature data on spruce and poplar.

[1]  J. V. Dam,et al.  Simplified Kinetic Modelling of Alkaline Delignification of Hemp Woody Core , 1994 .

[2]  F. Pla,et al.  Délignification en Milieu Alcalin de Bois Feuillus à l'Aide d'un Réacteur à Lit Fixe et à Faible Temps de Passage. Partie II. Développements Cinétiques , 1992 .

[3]  J. Genco,et al.  Hemicellulose retention during kraft pulping , 1990 .

[4]  G. Fahey,et al.  Neutral monosaccharide composition of various fibrous substrates: A comparison of hydrolytic procedures and use of anion-exchange high-performance liquid chromatography with pulsed amperometric detection of monosaccharides , 1989 .

[5]  P. W. Lane,et al.  Genstat 5: A Second Course , 1989 .

[6]  Astrid Rapetto-Labidi.  Etude de la délignification en continu du bois de peuplier en milieu basique : cinétique et chimie des procédés ; caractérisation des lignines extraites , 1989 .

[7]  Johnson F. Yan,et al.  Lignin 25. Kinetics of Delignification of Western Hemlock in Flow-through Reactors under Alkaline Conditions , 1989 .

[8]  F. E. Mera,et al.  Extended delignification, an alternative to conventional kraft pulping , 1988 .

[9]  J. Wiegel,et al.  Xylobiose and xylooligomers , 1988 .

[10]  J. Farkas,et al.  Effect of hemicelluloses on the papermaking properties of pulps prepared from poplar wood , 1987 .

[11]  P. J. Nelson,et al.  Delignification of Eucalyptus regnans wood during soda pulping , 1986 .

[12]  G. Gellerstedt,et al.  Structural Changes in Lignin During Kraft Pulping , 1984 .

[13]  E. Sjöström,et al.  Wood Chemistry: Fundamentals and Applications , 1981 .

[14]  J. Gierer,et al.  On the Course of Delignification During Kraft Pulping , 1980 .

[15]  N. Terashima.  REACTIONS OF LIGNIN DURING PULPING , 1980 .

[16]  D. Goring,et al.  ultrastructural arrangement of the wood cell wall , 1975 .

[17]  J. Kiss.  β-Eliminative Degradation of Carbohydrates Containing Uronic Acid Residues , 1974 .

[18]  Kyosti V. Sarkanen,et al.  Lignins : occurrence, formation, structure and reactions , 1971 .

[19]  R. Simonson.  The hemicellulose in the sulfate pulping process , 1971 .

[20]  J. Gierer.  The Reactions of Lignin during Pulping. A Description and Comparison of Conventional Pulping Processes , 1970 .

[21]  J. E. Stone,et al.  A structural model for the cell wall of water-swollen wood pulp fibres based on their accessibility to macromolecules , 1968 .

[22]  K. Sarkanen,et al.  Kinetic study on the alkaline degradation of cotton hydrocellulose , 1967 .

[23]  J. E. Stone,et al.  Effect of component removal upon the porous structure of the cell wall of wood , 1965 .

[24]  T. E. Timell,et al.  Recent studies on the polysaccharides of White Birch and other hardwoods , 1959 .

[25]  I. McDonald.  609. The chemistry of the wood cell wall. Part III. The isolation of beech hemicellulose A , 1952 .

[26]  G. R. Lusby,et al.  THE DELIGNIFICATION OF WOOD BY STRONG ALKALINE SOLUTIONS , 1937 .