Conductivity of AOT/Triton X-100 Mixed Reverse Micelles

Surfactants p-octyl polyethylene glycol phenyl ether (Triton X-100) and bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) were mixed to prepare reverse micelles with n-hexane, n-hexanol, and water. The effects of surfactant mass ratio, concentration of co-surfactant, volume ratio of water to oil, and temperature on the conductivity of the reverse micelles were studied. The electrochemical behavior of potassium ferricyanide (K3Fe(CN)(6))/potassium ferrocyanide (K4Fe(CN)(6)) in the mixed reverse micelles was investigated by cyclic voltammetry. The results indicate that the conductivity of the mixed reverse micelles is much higher than that of the single surfactant reverse micelles and it changes with the surfactant mass ratio w (w=m(AOT):m(Triton X 100)). When w changed from 0 to 0.4, the conductivity sigma increased linearly. The conductivity then increased slowly and stabilized at 576 mu S.cm(-1) when w was 0.96. Simultaneously, the increase in water content and temperature enhanced the conductivity while the addition of co-surfactant decreased the conductivity obviously. In the mixed micelle system, the redox peak potentials of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) were almost constant with a change in scan rate, and the redox potential gaps were about 75 mV. Furthermore, the ratio of the redox peak current for all scan rates was close to 1. The oxidation peak current increased linearly with the square root of scan rate. The results indicate that the Fe(CN)(6)(3-)/Fe(CN)(6)(4-) electrochemical reaction is reversible and is controlled by diffusion in the mixed reverse micelle system.