Salt effects on lignosulfonate and Kraft lignin stabilized O/W-emulsions studied by means of electrical conductivity and video-enhanced microscopy

The emulsifying properties of two lignosulfonate (LS) fractions and one Kra ft lignin fraction were studied under different experimental conditions. A method utilizing the conductivity of aqueous dispersions and the volume fra ction dispersed phase was used to study the creaming rates of the emulsions . The electrical conductivities were measured in the upper and the lower pa rt of the emulsions, respectively, in order to determine creaming rates. Vi deo-enhanced microscopy (VEM) pictures were used to characterize the drople ts, and droplet size distributions (DSD). The stability against creaming, c oalescence and flocculation was studied and it was found that the propertie s of the interfacial films containing LS were strongly affected by trivalen t aluminum, ferric and chromium ions. The bulk viscosities of the emulsions were determined for emulsions with different stabilities. (C) 2001 Elsevie r Science B.V. All rights reserved.