ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 10, pp. 1851–1855. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © N.I. Afanas’ev, S.B. Selyanina, N.V. Selivanova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 10,
Stabilization of the Oleic Acid–Water Emulsion
with Various Kraft Lignins
N. I. Afanas’ev, S. B. Selyanina, and N. V. Selivanova
Institute of Environmental Problems of the North, Ural Branch, Russian Academy of Sciences, Arkhangelsk, Russia
Received January 30, 2008
Abstract—The influence of the initial wood species and polymolecular characteristics on the characteristics of
the surface of solid-phase lignin was estimated, and the correlation of these parameters with the ability of kraft
lignins to stabilize the oleic acid–water emulsion was examined. The kinetics of breakdown of emulsions
stabilized with kraft lignin was studied.
Industrial pulp is produced today predominantly
by the kraft procedure. Lignin derivatives formed in
this procedure are soluble in alkalis, whereas in going
to acidic solutions they pass into the solid state. Solid
particles of kraft lignins have a large specific surface
area (up to 20 m
) and contain a large number of
polar groups (up to 14 mg-equiv
) . They have
high sorption power with respect to many classes of
substances and also efficiently stabilize oil-in-water
emulsions [1, 2].
In particular, a stable lignin–tall emulsion is
formed in synthesis of tall oil, by-product of kraft cel-
lulose manufacture (Fig. 1). As shown previously [3–5],
this emulsion is stabilized by kraft lignin.
It is well known [6, 7] that the stabilization
mechanism of emulsions depends on hydrophilicity
and lipophilicity of the solid emulsifier and, in particu-
lar, kraft lignin. Taking into account that kraft lignins
recovered from liquors formed in cooking of decidu-
ous and coniferous wood differ in topological structure
and chemical composition [8, 9] and, at the same time,
they are polydisperse and polyfunctional compounds,
it is reasonable to expect that the nature of their surface
and, accordingly, the ability to stabilize emulsions
should depend on the initial wood species and also on
the molecular weight and molecular-weight distribu-
tion. Although this statement is obvious, there are no
published data on the behavior of fractionated lignins
in the systems water-oil-lignin.
In this study, we examined the behavior of kraft
birch and spruce lignins and evaluated the influence of
their molecular weights on the stability of the oleic
acid–water system simulating the lignin–tall emulsion.
AND POLYMERIC MATERIALS
Fig. 1. Relative yields of (a) oil phase (η
), (b) acidic water
), and (c) emulsified layer (η
) vs. the settling duration τ
in production of tall oil by degradation of (1) deciduous
and (2) coniferous sulfate soap.