In vitro studies on the application of colloidal emulsion aphrons to drug overdose treatment

Colloidal emulsion aphrons (CEAs) are 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 dispersion, the emulsion-core sizes are mainly in 10-100 μm and that of the inner phase droplets are in 1-5 μm. CEAs not only behave analogously to emulsion liquid membrane (ELM) in extraction with advantages of high concentration ratio, counter-concentration extraction and combination of extraction with backwash together, but also have the large interface areas, easy scatteration and quick extraction which colloidal liquid aphrons (CLAs) possess. CEA extraction overcomes the restriction of partition equilibrium between the water and the oil phase that CLAs have. They have greater extraction capacity than CLAs. In this study, the application of CEAs to drug overdose treatment was studied using salicylic acid as the model drug, paraffin oil as the membrane phase, PEG-30 dipolyhydroxystearate (P135) as the hydrophobic surfactant, nonylphenol ethoxylate-10 (NP10) as the hydrophilic surfactant and NaOH solution as the receptor phase. Also some factors affecting the stability of this dispersion and extraction ratio were investigated. In order to prepare CEAs successfully, the concentrations of NP10 and P135 should be in 1.5-3.0% (w/v) and 0.25-1.0% (w/v), respectively, together with the ratio of the volume of oil phase to the volume of inner aqueous phase of CEAs, Roi ≥ 1:1. For the extraction of salicylic acid, the pH value of the feed phase was supposed to be lower than 2.0 and the suitable NaOH concentration of the receptor phase was higher than 0.02 mol/L. Under this condition, more than 98.7% of salicylic acid was transported into receptor phase in half a minute.