Pulping and biorefining
- General approach and principles
- Extraction-based methods
- Separation of valuable extractives from trees
- Choosing the right solvent – hydrophobic or hydrophilic?
- Stemwood extractives-based products
- Operation modes and procedures in industrial extraction processes
- Exudate gums and latexes
- Hot-water extraction
- Wood extractives – general description
- Factors contributing to the loss of extractives
- Chemical changes in extractives during storage
- Bark extractives – terpenes and terpenoids
- Bark extractives – polyphenols and other minor compounds
- Use of deep eutectic solvents (DES)
- Chemical and biochemical conversion
- Thermochemical conversion
- Kraft pulping
- Wood material handling systems
- Pulping process-general approach
- Pulping technologies
- Drying of chemical pulps
- Chemical (market) pulps drying plant applications
- Recovery of cooking chemicals and by-products
- Integrated biorefinery concepts
- Oxygen-alkali delignification
- Delignifying or lignin-removing bleaching
- Other delignification methods
- Chemimechanical pulping
- Mechanical pulping
- Pulp characterisation and properties
Lignin reactions – kraft pulping Lignin dissolution phases The overall effect of cooking time and temperature on kraft pulping can be estimated by a single numerical value calculated according to the concept of the so-called “H-factor” which has been developed by Vroom.1 In this method, the reaction rate at 100 °C is chosen as the
Authors & references
Author:
Raimo Alén
References:
- Vroom, K. 1957. The “H” factor: a means of expressing cooking times and temperatures as a single variable. Pulp and Paper Magazine of Canada 58:228−231.
- Alén, R. 2000. Basic chemistry of wood delignification. In: Stenius, P. (Ed.). Forest Products Chemistry. Fapet, Helsinki, Finland. Pp. 58−104.
- Kleppe, P. J. 1970. Kraft pulping. Tappi 53(1):35−47.
- Grace, T. M., Leopold, B., Malcolm, E. W. and Kocurek, M. J. (Eds.). 1989. Pulp and Paper Manufacture, Volume 5, Alkaline Pulping. 3rd edition. The Joint Textbook Committee of the Paper Industry, TAPPI&CPPA, USA and Canada. Pp. 23−44.
- Sjöström, E. 1993. Wood Chemistry − Fundamentals and Applications. 2nd edition. Academic Press, San Diego, CA, USA. Pp. 140−161.
- Gierer, J. 1970. The reactions of lignin during pulping. A description and comparison of conventional pulping processes. Svensk Papperstidning 73:571−596.
- Gierer, J. 1982. The chemistry of delignification. A general concept. Part I. Holzforschung 36:43−51.
- Gierer, J. 1982. The chemistry of delignification. A general concept. Part II. Holzforschung 36:55−64.
- Alén, R. and Vikkula, A. 1989. Formation of lignin monomers during kraft pulping of birch wood. Cellulose Chemistry and Technology 23:579−583.
- Alén, R. and Vikkula, A. 1989. Formation of lignin monomers during alkaline delignification of softwood. Holzforschung 43(6):397−400.
- Niemelä, K. and Alén, R. 1999. Characterization of pulping liquors. In: Sjöström, E. and Alén, R. (Eds.). Analytical Methods in Wood Chemistry, Pulping, and Papermaking. Springer Verlag, Heidelberg, Germany. Pp. 193−231.
- Pakkanen, H. and Alén, R. 2012. Molecular mass distribution of lignin from alkaline pulping of hardwood, softwood, and wheat straw. Journal of Wood Chemistry and Technology 32:279−293.
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This page has been updated 07.12.2020