CALPHAD aqueous solution model based on the BET approach: General theory

The Brunauer-Emmett-Teller (BET) model for adsorption has found extensive use in modelling of adsorption, surfaces and concentrated solutions. We present here a Gibbs energy minimiser based application of a BET and related GAB model, implemented using the ChemApp program library via ChemSheet. The basic model is constructed using solely ideal mixture phases. The use of a free energy minimiser readily enables various extensions, such as multicomponent adsorption and interactions between lattice sites. While the method presented is applicable to BET model problems in general, the emphasis in this work is on applications related to concentrated aqueous solutions.