A simple model for precisely describing liquid-liquid equilibrium and better understanding extraction mechanism

Describing distribution of solute equilibrium concentrations between two solvents is important for liquid-liquid equilibrium (LLE). Due to non-ideality of solutions, the distribution usually possesses non-linear characteristic. In this work, the non-ideality was simply represented by pseudo reaction (or chemical interaction) between the solute and the solvent without recourse to the complicated activity coefficient models. On this basis, a simple model, which combined physical partition and pseudo reaction equilibriums, was proposed and can precisely correlate various LLE systems, for example, the immiscible, the partially miscible, the organic, and even the electrolyte. More interestingly, the model can accurately reflect intrinsic mechanism by fitted parameters, that is, stoichiometric ratio of the pseudo reaction and total equilibrium constant for the interaction intensity. Besides, influence of the solute, the extractant, and temperature on the parameters was discussed deeply. This simple model is promising for precisely describing the LLE systems and better understanding their intrinsic extraction mechanism.