Framework for correlating the effect of temperature on nonelectrolyte and ionic liquid activity coefficients

A power‐law expression is proposed for correlating the temperature dependence of infinite‐dilution activity coefficients ( γ i j ∞) for nonelectrolyte solute–solvent binary pairs and for pairs including an ionic liquid:ln ⁡ γ i j ∞ ( at   T ) / ln ⁡ γ i j ∞( at   T ref ) =(T ref/ T )θ i j, where θ ij  = 0 for Lewis–Randall ideal solutions, θ ij  = 1 for classic enthalpy‐based Scatchard–Hildebrand regular solution and van Laar models, and −5 < θ ij < 5 for most real binaries. The exponent θ ij is a function of partial molar excess enthalpy (h ¯i j E , ∞) and entropy (s ¯i j E , ∞) such thatθ i j = 1 / [ 1 − ( Ts ¯i j E , ∞ /h ¯i j E , ∞ ) ] . Real binaries are classified into seven types corresponding to distinct domains ofγ i j ∞and θ ij . The new method provides a framework for correlating phase‐equilibrium driven temperature effects for a wide variety of chemical and environmental applications. © 2014 American Institute of Chemical Engineers AIChE J , 60: 3675–3690, 2014