ULTRAFILTRATION OF O/W EMULSIONS STABILIZED BY LIMITING AMOUNTS OF TALL OIL

Ultrafiltration of oil-in-water (O/W) emulsions was investigated with tall oil as the emulsifier. Most of the experiments were carried out at pH almost-equal-to 11 in order to keep the tall oil in its surfactant mode. The permeate flux increased with increasing flow velocity, but decreased with increasing pressure (1-4 bar). The emulsions could be stable at very low emulsifier/oil (E/O) ratios, but permeate flux decreased with decreasing E/O ratio. The emulsions could be partially broken with acid in the pH range 6.5-8.5 and totally separated at pH 3.5. At alkaline pH the emulsions could be broken with salt. A higher concentration of salt was needed when the E/O ratio was high. Aniline could be continuously extracted into the oil droplets of the emulsion during ultrafiltration from an aqueous solution fed to the emulsion with the same rate as permeate was formed. The extraction of aniline could be carried out to a degree which exceeded the expectations based on its W/O distribution factor.