Micelle Formation and Phase Equilibria of Surface Active Components of Wood

Abstract

Studies of surfactant properties of sodium abietate and sodium oleate at 60°C show that both compounds form small micelles at low concentrations. At high concentrations of oleate, rod-shaped micelles are formed. Addition of salt causes the oleate micelles to grow while the abietate micelles remain small. Abietate and oleate when mixed in roughly equimolar proportions form small mixed micelles that remain soluble at much higher salt concentrations than either of the pure compounds. All types of micelles show comparable solubilization capacities. Oleate and abietate also form lamellar liquid crystalline phase with water. With oleic acid the oleate forms hexagonal and isotropic liquid crystalline phases as well as reversed micellar solutions, while sodium abietate/abietic acid forms only lamellar phase. The results make it possible to draw some tentative conclusions concerning the behaviour of these surface active components in black liquor, their removal in the washing of pulp and their dispersability. These conclusions are illustrated by comparison with real black liquor systems.