Equilibrium modeling of ion adsorption based on Poisson–Boltzmann equation

• A phenomenological model to represent the bulk adsorption of ions is proposed.
• The model proposed was based on a previous surface adsorption one.
• There was improvement and simplification in the previous model.
• The model was successful in accurately describe the investigated cases.
• It reduced the number of adjustable parameters with no lose in the fit quality.

A phenomenological model representing ion adsorption equilibrium is proposed. It is an extension of the model used to represent surface adsorption, and it is intended to interpret bulk adsorption data. The fundamental equations of the model were established for fluid and solid phases mass balance and for the spatial distribution of ions across the sample. The electric field distribution in the system, modeled on Poisson's equation, and the chemical potential behavior were determined as a function of fluid phase equilibrium concentration. The concentration of ions as a function of electric potential is given by Boltzmann distribution. The proposed model was successfully tested to represent equilibrium adsorption of metallic ions in zeolite, showing results similar to conventional isotherms.

Figure optionsDownload as PowerPoint slide