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 Kraft lignin fraction were studied under different experimental conditions. A method utilizing the conductivity of aqueous dispersions and the volume fraction dispersed phase was used to study the creaming rates of the emulsions. The electrical conductivities were measured in the upper and the lower part of the emulsions, respectively, in order to determine creaming rates. Video-enhanced microscopy (VEM) pictures were used to characterize the droplets, and droplet size distributions (DSD). The stability against creaming, coalescence and flocculation was studied and it was found that the properties of the interfacial films containing LS were strongly affected by trivalent aluminum, ferric and chromium ions. The bulk viscosities of the emulsions were determined for emulsions with different stabilities.