Surface chemical aspects of the behavior of soaps in pulp washing

• In a kraft pulp washing line the wood resin consists of fatty acid and rosin acid soaps and a variety of neutral components. The removal of this material in the washing line is highly dependent on soap solubility, micelle formation, solubilization and the colloidal stability of precipitated resin particles. This papers summarizes several studies of the colloidal behavior of resin in model systems consisting of sodium abietate, sodium oleate and a model mixture of neutral components, and presents new data on micellization and solubilization. The highest solubility of the soaps and maximum solubilization of neutral compounds occurs at moderate ionic strength in mixed oleate/abietate solutions (1:2-2:1 by weight). Micelle formation is promoted by low temperature and moderate ionic strength; the solubilizing capacity of the micelles increases with temperature. Colloidal particles formed by precipitated resin are stabilized by kraft lignin. The model results are compared with an analysis of the distribution of resin in a pulp washing line. This distribution can be clearly understood from the results of the model study.

Keyword

Washing

Surface properties

Soap

Colloids

Micelles

Wood resin

Kraft pulps.

Publication and Content Type

ref (subject category)

art (subject category)