Solubilities of AOT analogues surfactants in supercritical CO2 and HFC-134a fluids

A series of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) analogue surfactants [sodium dibutyl sulfosuccinate ( DBSS), sodium dipentyl sulfosuccinate (DPSS), sodium dihexyl sulfosuccinate (DHSS), and sodium dioctyl sulfosuccinate (DOSS)] were synthesized and characterized with H-1 NMR and elemental analysis. The solubilities of surfactants in supercritical CO2 (scCO(2)) and supercritical 1,1,1,2-tetrafluoroethane (HFC-134a) fluids at a temperature range from (308 to 338) K and under pressures of (10 to 30) MPa were measured using a static method coupled with gravimetric analysis. The solubilities of these surfactants are much higher in HFC-134a fluid as compared with that in scCO(2.) The solubilities increased with increasing temperature and pressure for both scCO(2) and HFC-134a fluids. The solubilities in scCO(2) increased with increasing carbon atom number of surfactant, whereas they decreased with increasing carbon atom number of surfactant in HFC-134a. The density of scCO(2) was simulated with the Peng-Robinson (P-R) equation. The experimental data were used to validate the accuracy of the P-R equation.