A new kind of dispersion-colloidal emulsion aphrons

A new kind of dispersion named as colloidal emulsion aphrons (CEAs) has been prepared and their structure was postulated. They can be considered as the micron-sized water-in-oil (W/O) emulsion-cores encapsulated by a “soapy shell” consisting of multi-layer surfactant molecules. In this work, CEAs were made using span 80 (sorbitan monooleate) as hydrophobic surfactant, NP 10 (nonylphenol ethoxylate) as hydrophilic surfactant and n-heptane as the oil phase. In this dispersion, the emulsion-core sizes are mainly in 10-100 μm and that of the inner phase droplets are in 1-5 μm. Some of CEA properties, especially the dispersibility and stability were studied. CEAs disperse more easily in water compared with that of emulsion liquid membranes (ELMs). Some affecting factors, such as deposit time, mixing speed, oil-internal ratio and concentrations of hydrophilic and oil-soluble surfactants on leakages of CEA dispersion were characterized under various conditions by using Co2+ as a tracer ion. In order to gain the high stability and low leakage, suitable surfactant concentrations and oil-inner phase ratio (Roi) are necessary for CEA preparation. In this study, span 80 and NP 10 were supposed to be in 0.5-2.5% (w/v) and 0.25-0.75% (w/v), respectively and Roi ≥ 1. Because of the large interface areas and high dispersibility which CEAs possess, it is hopeful for CEAs to fulfill the requirement of quick extraction without sufficient stirring, such as the treatment of drug overdose or food poisoning.