The Interdiffusion of Counterions in a Cation-Exchange Membrane

Abstract

The apparent interdiffusion coefficient has been determined from the bulk concentration of electrolyte solution and interdiffusion time. The integral interdiffusion coefficient can be estimated from the results using the Donnan membrane equilibrium. The data show that the interdiffusion is controlled by the component with low concentration, and the relationships between the apparent interdiffusion coefficient and temperature can be expressed by an Arrhenius plot for various interdiffusion systems. In the cation exchange membrane Selemion CMV the apparent interdiffusion coefficient DAB and interdiffusion activation energy EAB for various systems have magnitudes in the relative order DH-li < DH-Na < Dh_k and EH_Li > EH_Na > EH_K, respectively. The interdiffusion of counterions is independent of the kinds of co-ions at low concentration of the solution. There is an increase of integral interdiffusion coefficient and a decrease of interdiffusion activation energy with increasing bulk concentration of the electrolyte solution.

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

“…Ion transport in ion-exchange dense polymer membranes is normally quantified by ion diffusion coefficients. A variety of experimental techniques based on the Nernst-Planck equation have been employed to measure the diffusion coefficients of inorganic ions in these membranes, including a Donnan dialysis method [9][10][11][12], radiotracer method [13,14] and conductivity method [15][16][17][18]. The conductivity method is the most often used as diffusion coefficients measured in the presence of an external driving force are closer to the real operation of the membrane process.…”

Selective transport of metal ions through cation exchange membrane in the presence of a complexing agent

“…The concentrations of the metal ions were determined by use of an atomic absorption spectrophometer (Model 551, Instrumentation Laboratory Inc.). However, the measured concentration had to be corrected due to the change of solution volume during sampling (Huang and Lian, 1979). The permeation fluxes of the metal ions were calculated from linear slopes of the ionic concentration versus time curve with the least squares method.…”

“…Application of this process can simultaneously solve two important environmental problems, for the recovery and enrichment of valuable ions and for the removal of undesirable ions from wastewater (Kim, 1980;Lonsdale, 1982). A number of investigations have performed on the systems of alkali metal ions (Takahashi et al, 1989;Huang and Lian, 1979), alkali earth metal ions (Cox et al, 1984), transition metal ions (Brajter and Slonawska, 1988; Sudoh et al, 1987;Wen and Hamil, 1981), and rare earth metal ions (Davis et al, 1971; Mastsuyama et al, 1991).…”