Abstract
The effect of process parameters involved in predispersed solvent extraction (PDSE) on the stability of colloidal liquid aphrons (CLAs) was investigated. Tertiary amine, trioctylamine (TOA) was used as an extractant of succinic acid and 1-octanol was used as diluent for lowering toxicity and viscosity of TOA. CLAs were formulated with an TOA/1-octanol/Tergitol-15-S-3 solvent phase and Succinic acid/Sodium dodecylbenzene sulfonate (SDBS) aqueous phase. Visual observation and light scattering measurements by UV/spectrophotometer were used as a method of obtaining the breakup speed of CLAs. The influence of pH, solvent composition, ion species were investigated based on these measurements. At low pH values, excess hydrogen ions in aqueous phase leaded to protonation of the head-group of the water-soluble surfactant located on the outer soapy shell of CLAs and lowered the stability. As the concentration of TOA increased, the stability of CLAs decreased because of the increasing basicity of aphron core. The stability of CLAs displays a strong dependence on ionic strength of aqueous phase because the energy gap between continuous phase and bilayer of surfactant at outer soapy shell decreases with the contained ion concentration.
