A generalized model for the measurement of effective diffusion coefficients of heterovalent ions in ion exchangers by the zero-length column method

Model for the determination of diffusion coefficients of heterovalent ions in macroporous ion exchange resins by the zero-length column method

“…This fact would indicate that the driving force has an important influence on the elution of ions. This behavior is also observed in geliform ion exchange resins (Valverde et al, 2004).…”

“…As initial value for the solid phase diffusion coefficients those obtained in a previous works for Amberlita IR-120 were considered (Valverde et al, 2004).…”

“…In this way, the ion exchange model is reduced to a stiff system of ordinary differential equations taking into account the initial and boundary conditions. The mass balance for the ZLC has been obtained from the conventional mass balance equation (Valverde et al, 2004). In this case, there are two contributions to the flux of ions through the resin particle (in the porous and in the solid).…”

“…According to that, batch, shallow bed or single-particle methods have been applied for the measurements of intraparticle diffusivities in ion exchangers. In previous papers (Rodriguez et al, 1998;Valverde et al, 2004), the authors developed models for measuring the intraparticle diffusivities of monovalent and heterovalent cations in geliform ion exchange resins by the very easy and fast experimental zero-length-column (ZLC) technique. In both works, aqueous binary systems were used to test the validity of the models, the accuracy and its reliability.…”

Effect of pH on cadmium (II) removal from aqueous solution using titanosilicate ETS-4

“…Batch experiments were carried out, and the effect of pH was carefully analyzed in the range 4-8. Modelling was accomplished using a Nernst-Planck based model [22][23][24].…”