Effect of Inorganic Salts on the Phase Behavior of Microemulsion Systems Containing Sodium Dodecyl Sulfate

The effect of different inorganic salts on the phase behavior of the microemulsion systems comprising of SDS/aliphatic acid or alcohol/alkane/aqueous salt has been studied with an ϵ-β fishlike phase diagram method. The related physicochemical parameters, such as the solubility of the acid (alcohol) (ϵ B ), the composition of the interfacial layer (A S ), the mass fraction of the acid (alcohol) and surfactant contained in the interfacial layer in the whole system (ϵ i and β i ), and the optimum solubilization ability (SP*) of the microemulsion systems were calculated and discussed. As the concentration of salt (CaCl2) increases, the solubilization ability of the system would decrease for the aliphatic acid-based system, but would increase for the alcohol-based system. In the aliphatic acid-based and the alcohol-based microemulsion systems, the solubilization ability (SP*) of the microemulsion system was in the same salt order MgCl2>CaCl2∼SrCl2 and Ca (NO3)2>CaBr2>CaCl2.