Dilution Method Study on the Interfacial Composition, Thermodynamic Properties, and Structural Parameters of the [bmim][BF4] + Brij-35 + 1-Butanol + Toluene Microemulsion

The dilution method was used to research the interfacial composition, thermodynamic parameters, and structural parameters of [bmim][BF4] + Brij-35 + 1-butanol + toluene ionic liquid/oil (IL/O) microemulsion. The effects of the mole ratio of [bmim][BF4] to Brij-35 (R) and the addition of water on the above parameters were investigated. Studies of the interfacial composition revealed that cosurfactants at the interface (nai) increased with the increase of R and decreased with the increase of additional water. This indicated that more cosurfactants were required to form a IL/O microemulsion than that of the traditional water/oil (W/O) microemulsion. The ΔGto values of transfer process of cosurfactants from the continuous oil phase to the interfacial region were all negative, which suggested that the IL/O microemulsion formed spontaneously. The absolute values of ΔGto increased with the increase of R and additional water. The results showed that the IL/O microemulsion with additional water formed more spontan...