Predispersed solvent extraction of succinic acid using colloidal liquid aphrons in a column

Abstract

In this study, predispersed solvent extraction (PDSE) of succinic acid using colloidal liquid aphrons (CLAs) in a column was investigated. Tertiary amine, trioctylamine (TOA) was used as an extractant. TOA acts as complexing agents with the succinic acid that facilitates the distribution of succinic acid into organic phase. Size distribution and stability of CLAs were measured for application to column. According to the increase of concentration of TOA in octanol, the stability of CLAs decreased and the CLAs represented high stability after the reaction with succinic acid. It is because the basicity of amine is neutralized by reaction with succinic acid and does not repel with anionic surfactant, SDBS, anymore. The stability of CLAs displays a strong dependence on ionic strength because the energy gap between continuous phase and bilayer of surfactant at outer soapy shell decreases with the contained ions. Ammonium sulfate which gives the lowest stability to CLAs was selected as breaking solution. The effect of operating parameters on batch PDSE was investigated. The extraction efficiency of PDSE is similar to that of mixer/settler type in spite of extremely short contact time. It is due to the enormous surface area of CLAs. Solvent recovery, the most important problem in PDSE, was investigated on the basis of the stability and extractability data in batch operation. The conventional separation method of predispersed solvent, colloidal gas aphron (CGA) flotation was examined first. The effect of surfactant concentration, flotation time and flow rate of CGAs and phase volume ratio (PVR) of CLAs were studied. Although enough flotation time was given, solvent recovery was limited to 70 %. It is because the smaller CLAs have less electrostatic forces, thus their ability to attach on surface of CGAs is limited. Total recovery of succinic acid used 0.5 mol/kg TOA/1-octanol was about 39 % in this method. Based on the stability in solution containing ions, breaking sol...