Temperature dependence of liquid-liquid interfacial tension and universal critical amplitude ratio: an experimental study

Results of new measurements of the temperature dependence of the liquid-liquid interfacial tension σ of the system cyclohexane/aniline are reported. The system specific value of the critical amplitude σ0 of the interfacial tension has a value of σ0 = 38.5 mN m−1. It is combined with the value of the system specific critical amplitude ξ0+ of the correlation length of local concentration fluctuations to calculate the amplitude ratio Rσ,ξ+ = [σ0(ξ0+)2]/kBTc (kB, Boltzmann constant; Tc, critical temperature). The experimental value of Rσ,ξ+ for that system is Rσ,ξ+ = 0.41. It is at the upper limit of experimental Rσ,ξ+ values reported in the literature for five one component systems and eight binary mixtures (0.283 < Rσ,ξ+ < 0.410, mean value Rσ,ξ+ = (0.37 ± 0.03); theoretical value, Rσ,ξ+ = 0.36).