How do you find self-diffusion coefficient?
The self-diffusion coefficient is given by g · a2 times the number of jumps per sec that the diffusing particles make. Gm is the free enthalpy for a jump, i.e. the free enthalpy barrier that must be overcome between two identical positions in the lattice.
How do you calculate membrane ion exchange capacity?
The IEC is defined as the milliequivalent of ion-exchange groups included in a 1-g dry membrane (meq (g dry membrane)− 1). The concentration of ion-exchange groups is obtained by dividing the IEC with the water content in a 1-g dry membrane (meq (g H2O)− 1).
What is ion exchange equilibria?
Ion exchange is an adsorption process which occurs when there is equilibrium between a fixed number of ions on the resin phase and ions in solution. The concentrations in the solution and resin phases can be expressed in the form of mole fractions.
What is the unit of coefficient of diffusion?
square metres per second
The SI units for the diffusion coefficient are square metres per second (m2/s).
What is R in diffusion coefficient?
Here, k is the Boltzmann constant, μ is the solvent viscosity, and r is the radius of the diffusing particle. This equation is derived on the assumption that the particles obey Stokes’ law for drag, such that the drag exerted on diffusing molecules, by the solvent molecules, can be computed.
What is the diffusion coefficient of exchange resin?
of ions in the exchange resin. In chapter four is presented a model for the diffusion process occuring in a spherical resin particle. This model defines a diffusion coefficient which is dependent on the ion concentrations of the resin phase and is developed to the point of an integral interdiffusion coefficient.
What is the difference between ion diffusivity and diffusion coefficient?
diffusion coefficient is obtained under equilibrium conditions (resin phase contains only one ion species) whereas the ion diffusivities are operative under conditions of changing resin phase concentration (the two species of ions and their relative concentration are continuously changing). The Nernst-Plank
What is the interdiffusion coefficient of counter ion species?
Interdiffusion Coefficients The inter diffusion of two counter ion species should produce a reciprocal integral inter diffusion coefficient that, varies with resin capacity. A constant coefficient should result only if each species diffuses at the same rate (ie. equivalent self-diffusivities). Figures 31 through 39 show transformed results
What determines the self-diffusion rate of cations in desulfonated ion exchangers?
Boyd, Soldano and Bonner (25) investigated self-diffusion rates of cations in desulfonated ion exchangers. The authors found that the diffusion coefficients increased initially with decreasing exchange capacity but at still lower capacities, the coefficient decreased, indicating interaction between the diffusing ion’ and the environment.