Application of thermodynamics in a specific force field to the adsorption of Al ions on the chelating resins Ostsorb Oxin, Ostsorb Salicyl, Spheron Oxin, and Spheron Salicyl: Mathematical analysis of sorption isotherms using nonlinear mean square software

The sorption mechanism of Al³⁺ on chelating resins by means of mathematical analysis of sorption isotherms using nonlinear mean square software was studied. This method should yield more detailed information than classical thermodynamics and should be more flexible than the statistical-mechanical method, so that it would make it possible to obtain fairly easily relations directly applicable in practice. This model defined the specific potential Φ_Al^R for the ion in a resin (which depends on properties of resin and ion). On the basis of this model, N and PO isotherms were derived. To study the sorption mechanism, the Freundlich, Langmuir, N and PO equations (models) of isotherms were used. It was estimated that the functional groups (8-hydroxyquinoline and salicylate) in the studied chelating resins influence Φ_Al^R and thus their mechanism and sorption capacity.