Density and stability of oil-in-water emulsions

   The stability of oil-in-water emulsions is determined by the physicochemical properties of oil, as well as the composition of emulsified water.   The present work aims to study the effect of concentration and temperature on the density and stability of oil-in-water emulsions. Classical oil emulsions of the first type were prepared with aqueous CaCl2 solution and oil from the Yarakta field.   The ratios of the hydrocarbon component to the aqueous phase were as follows, vol %: 5:92, 10:87, 15:82, 20:77, 25:72, 30:67, and 35:62 with the addition of emulsifier. The density of emulsions was studied using the pycnometer method, with a measurement error of up to ±0.01 kg/m3. The method consists in accurately determining the mass of the test solution and distilled water, which occupy a known volume (50 cm3) in the pycnometer, and using a high-precision analytical scale. The obtained regression equations provide a means to calculate the densities of oil-in-water emulsions within the studied temperature (20–60 °С) and oil concentration (5–35 vol %) ranges. The derived empirical equations can be used in practice. It is shown that with increasing oil concentration and temperature, the density of emulsions decreases. The stabilizing ability of oil-in-water emulsions was evaluated in terms of luminous transmittance: the luminous transmittance value served as a stability criterion of emulsions in water. It was experimentally confirmed that the stabilizing ability of emulsions decreases with increasing temperature. The obtained results can be used in the study of regularities defining the direction and extent of chemical transformations and stabilization of oil-in-water emulsions, as well as in the solution of practical issues related to their destruction.