Effect of Polysaccharide on Flocculation and Creaming in Oil-in-Water Emulsions

Abstract

Creaming of the droplets in 20% alkane-in-water emulsions in the presence and absence of non-adsorbing polymer is reported in the form of oil concentration-height profiles collected at intervals of time. Without polymer, the polydisperse droplets (stabilised by non-ionic surfactant) cream individually at a rate determined by their diameter. Measurement of creaming rates enables the distribution of hydrodynamic diameters to be inferred, and it agrees well with the size distribution from a light diffraction method. In the presence of hydroxyethylcellulose in the continuous phase at a concentration exceeding 0.03%w/w, the droplets flocculate, and the creaming rates are used to estimate the size of the pores in the flocculated droplet network. At 0.03% polymer, flocculated and individual particle phases are in coexistence. Direct evidence for a depletion mechanism of flocculation is presented.