Influence on illitic clay addition on the stability of sunflower oil in water emulsion

Abstract

Due to increasing demand for natural cosmetics, research about Pickering-Ramsden emulsions stabilized with natural colloidal particles like clay minerals also increases. There are a lot of studies about colloidal stability of emulsions containing clay minerals, but only few about illite containing clays that are widely used in cosmetic products. The ability of natural and purified illitic clays to stabilize sunflower oil-in-water emulsions with oil/water mass ratio 40:60 is investigated. Cosmetic products used in health care should be slightly acidic and as close as possible to skin’s pH (4.5–5.5), but the presence of carbonates can cause alkaline media and irritate the skin. Therefore, one part of used clays was purified from carbonates. Pickering-Ramsden emulsions were prepared with clay concentration of 3 and 6 mass% at neutral (pH 7–8) and acidic (pH 5.5) environment. The stability of emulsions was compared by using two methods – sedimentation and centrifugation based on the measured amount of separated oil. Emulsions with 6 mass% clay samples were significantly more stable than with 3 mass% clays. The stability of emulsions was also improved by the use of purified illitic clays (after the removal of carbonates) and at acidic pH 5.5. The increase of emulsions’ stability is attributed to the viscosity. The higher the viscosity, the less oil was separated.