Langmuir and Surface Complexation Models for Ion Exchange Equilibria on Strong Acid Resins

Abstract

The application of fitted Langmuir isotherms to experimental data for the determination of the ion exchange equilibrium constants defined in the surface Complexation model (SCM) was analyzed. Isotherms of the exchange of H⁺/Na⁺, K⁺ with sulfonated polystyrenic gel type and macroporous and hyper-crosslinked (macronet) resins were measured at 298 K and 0.01 mol/L total concentration of the external solution and the SCM equilibrium constants were deduced. Even if the diffuse layer has a significant contribution for a restricted domain, the predicted SCM isotherms are in good agreement with the experimental and fitted Langmuir isotherms. The effects of the resin texture on ion exchange equilibria were revealed.