Sorption and diffusion of organic acid ions in anion exchange membranes: Acetate and lactate ions as a case study

Manning condensation in ion exchange membranes: A review on ion partitioning and diffusion models

“…Wang et al studied the ionic conductivity of IEMs equilibrated with differing salts: they investigated AR103 and AR204 equilibrated with NaAc (sodium acetate) and NaLa (sodium lactate) between 0.1 and 1 M and at pH F I G U R E 2 9 (A) and (B) Salt diffusion coefficients in IEMs as a function of external upstream salt concentration. 17 83 The authors found good agreement between the modeled values and experimental results when using theoretical ξ values and fitted α values (Figure 32). The pH and concentration dependence of the modeled Ac À diffusivities were predicted similarly well by utilizing the values of ξ fitted from their sorption analysis with the Donnan-Manning model; these values for ξ were below ξ crit , so no additional adjustable parameter was needed for calculating the diffusivities for the ξ fit conditions.…”

“…Sodium acetate (NaAc) and sodium lactate (NaLa) partitioning data were produced by Wang et al over an external concentration range of 0.1-1 M with the intention of testing the Donnan-Manning model's applicability to ions common for food processing applications (Figure 9). 83 The NaLa data were well predicted by the Donnan-Manning model using the theoretical values of ξ, with a small improvement possible by treating ξ as an adjustable parameter. Meanwhile, the NaAc data were significantly overestimated by the predictions of the Donnan-Manning model.…”

“…Equilibrium co-ion concentration versus external solution salt concentration for anion-exchange membranes, AR103 and AR204, equilibrated with (A) sodium acetate (NaAc) and (B) sodium lactate (NaLa) solutions. 83 The symbols represent experimental data, the dashed lines represent the co-ion concentrations predicted by the Donnan-Manning model, and the solid lines represent the co-ion concentrations calculated from the Donnan-Manning model with ξ as a fitting parameter. Source: Adapted with permission from Reference 83, 2020, Elsevier linker, in an attempt to give a more realistic estimation of b. AMPS and long-chain (n ¼ 10 or n ¼ 13) PEGDA possess very different sizes and contour lengths, so the relatively simple Equation (13) may not be appropriate for this set of monomers.…”

“…Manning dealt with this question many years after introducing his theory, detailing how all higher-valent counter-ions should condense before ions of lesser F I G U R E 3 2 Counter-ion diffusion coefficients in AR103 and AR204 membranes contacted by (A) sodium acetate (NaAc) and (B) sodium lactate (NaLa) solutions. 83 The symbols represent the experimental data extracted from ionic conductivity measurements. The lines represent predictions by the Donnan-Manning/Manning-Meares models with the theoretical values for ξ (blue line) as well as the ξ values fitted using partitioning data (solid black).…”

Diffusion Permeability of Cation-Exchange Membrane in Different Solutions

“…It was also observed that the increase in the temperature of the NaCl solution leads to an increase in permeability of membrane. This may be due to increase in the penetration rate and thus Wang et al [2020], studied the diffusion permeability of two anion exchange membranes (AR103 and AR204) and found that at the same concentration, the diffusion coefficient of sodium acetate is lesser than the value of sodium chloride (NaCl). This can be explained by their Stokes radius (i.e., Cl − (0.121 nm) is less than Ac − (0.194 nm)).…”