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

Abstract

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 σ 0 of the interfacial tension has a value of σ 0 = 38.5 mN m −1. It is combined with the value of the system specific critical amplitude ξ 0 + of the correlation length of local concentration fluctuations to calculate the amplitude ratio R σ, ξ + = [ σ 0( ξ 0 +) 2]/ k B T c ( k B, Boltzmann constant; T c, critical temperature). The experimental value of R σ, ξ + for that system is R σ, ξ + = 0.41. It is at the upper limit of experimental R σ, ξ + values reported in the literature for five one component systems and eight binary mixtures (0.283 < R σ, ξ + < 0.410, mean value 〈 R σ, ξ +〉 = (0.37 ± 0.03); theoretical value, R σ, ξ + = 0.36).