Ion exchange kinetics in removal of small ions. Effect of salt concentration on inter- and intraparticle diffusion

Adsorption kinetics of DowexTM OptiporeTM L493 for the removal of the furan 5‐hydroxymethylfurfural from sugar

“…Those models regard the adsorbent as a two‐component (macropororous) system with diffusion through the pores or over the pore surfaces (heterogeneous) or the adsorbent is considered as a bulk material (homogeneous) with diffusion in the bulk phase. Also a combination of both is possible . The homogeneous solid diffusion model (HSDM) is frequently used to describe adsorption kinetics of solutes on adsorbents.…”

“…Second, although Optipore is classified as a macroporous resin that contains small pores, literature on hypercrosslinked resins states that the porous structure is different from common heterogeneous macroporous resins and that is rather regarded as a homogeneous single phase polymeric gel . For homogeneous materials, such as gel type materials, the HSDM very well describes the mass transfer mechanism …”

“…Also a combination of both is possible. 14 The homogeneous solid diffusion model (HSDM) is frequently used to describe adsorption kinetics of solutes on adsorbents. This model assumes that molecules are first adsorbed at the external surface of the resin bead, and then diffuse further into the particle as a result of surface concentration gradients.…”

“…15 For homogeneous materials, such as gel type materials, the HSDM very well describes the mass transfer mechanism. 14 The kinetic HSDM model that describes adsorption in a column is based on the mass balance of the adsorbate. The following is assumed: 10 • There is no concentration gradient over the bed.…”

Thermodynamics of Ion Exchange

“…To explain ion exchange equilibria some common models are used. First type of this model is based on the mass action law [Gorka et al, 2008;de Lucas et al, 1992;Melis et al, 1995;Valverde et al, 1999]. In the second group ion exchange is treated as an adsorption process [Gorka et al, 2008] and in the third, the solid phase is considered to provide sites with fixed charges for ion exchange, as well as sites on which molecular adsorption takes place [Gorka et al, 2008;Novosad & Myers,1982;Myers & Byington, 1986;Ioannidis & Anderko, 2001].…”