Water transport by osmosis through a high-internal-phase, water-in-oil emulsion

Abstract

Agglomeration of ultrafine hydrophobic particles can be performed using high-internal-phase (HIP), water-in-oil emulsions as the binder. The ultrafast particle recovery achieved using these emulsions can be attributed to the presence of thin, permeable oil films as its organic phase. The internal aqueous phase of these emulsions contains salt, which drives water absorption through these permeable oil films during agglomeration, greatly reducing the effects of the lubrication resistance to particle collision, adhesion and hence agglomeration. In this study, the water permeation was quantified by studying the growth of cylindrical rivulets placed in fresh water. The rivulet diameter increased approximately with the square root of time, suggesting a diffusion-limited process. Water transport rates increased about three fold with increasing internal salt concentration of the emulsion from 0.5 wt% to 10 wt%.