Multiple Pickering emulsions stabilized by organic pigment particles: properties and ion release

The possibility of forming water-in-oil-in-water (w/o/w) multiple emulsions stabilized solely by a mixture of organic pigment particles is demonstrated. The influence of shearing speed on both inner water drop and oil globule size is studied; both decrease with increasing shearing speed. We also investigate the effect of particle concentration for both pigments on the stability and drop size of w/o/w emulsions. The water drop and oil globule sizes decrease progressively once the particle concentration exceeds 0.5 wt%; this value corresponds to the minimum concentration required to form stable w/o/w emulsions. Finally, the release of magnesium ions from internal water drops to the external aqueous phase is studied. The release is very low over a period of one month.