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The Kappa number estimates the amount of chemicals required during bleaching of wood pulp to obtain a pulp with a given degree of whiteness. Since the amount of bleach needed is related to the lignin content of the pulp, the Kappa number can be used to monitor the effectiveness of the lignin-extraction phase of the pulping process.
the Kappa number, indicating lignin content in pulp; represents: the Von Kármán constant, describing the velocity profile of turbulent flow; the kappa curve, a two-dimensional algebraic curve; the condition number of a matrix in numerical analysis; the connectivity of a graph in graph theory; curvature
The anthraquinone is reduced to 9,10-dihydroxyanthracene which then can react with lignin. The lignin is degraded and becomes more watersoluble and thereby more easy to wash away from the pulp, while the anthraquinone is regenerated. This process gives an increase in yield of pulp, typically 1–3% and a reduction in kappa number. [8]
Cohen's kappa, also known as Kappa statistic Fleiss' kappa , another measure of inter-annotator agreement Kappa number , a measure of lignin content in wood pulp
Numbers very close to, but below one are often expressed in "nines" (N – not to be confused with the unit newton), that is in the number of nines following the decimal separator in writing the number in question. For example, "three nines" or "3N" indicates 0.999 or 99.9%, "four nines five" or "4N5" is the expression for the number 0.99995 or ...
The dry matter content of lignins is the residue after drying at specified conditions. Any matter that is volatile at the drying conditions is not included in the dry matter content. The moisture content can be approximated by 100% minus the dry matter content. To determine the dry matter content, The sample is dried at a temperature of 105±2 °C.
Sulfite pulps now account for less than 10% of the total chemical pulp production [3] and the number of sulfite mills continues to decrease. [5] [6] [7] Magnesium was the standard counter ion until calcium replaced it in the 1950s.
Idealized structure of lignin from a softwood. Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. [1] Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily.