Critical Behavior of {Water + AOT + Decane} Microemulsion with Small Molar Ratio of Water to AOT

• DOI: 10.1007/s10953-009-9451-y
• Publication Date: 2009-08-26T15:14:04Z
• Authors: Hong-Lan Cai; Xue-Qin An; Hui-Hong Lü; Wei-Guo Shen
• Keywords: Microemulsion; Decane; Binodal; Volume fraction

The coexistence curves of (T,n), (T,φ) and (T,ψ) (n,φ,ψ are the refractive index, the volume fraction, and the effective volume fraction, respectively) for a ternary microemulsion system of {water + sodium di(2-ethylhexyl) sulfosuccinate (AOT) + n-decane} with the molar ratio 25.1 of water to AOT have been determined at constant pressure within about 7 K from the critical temperature T c by measurements of refractive index. The critical exponent β has been deduced from the (T,n), (T,φ) and (T,ψ) coexistence curves within 1 K above T c . They were 0.323, 0.327, and 0.329, respectively, and were consistent with the 3D-Ising value. Furthermore, the experimental results have been analyzed to obtain critical amplitudes B and the Wegner-correction terms B 1, to examine the diameters of the coexistence curves and to discuss the goodness of density variables for constructing order parameters.