A. A. Zagorodni Ion Exchange Materials: Properties and Applications Elsevier:2006
Book - Applets - Applet 11

Applet 11

Equilibrium model of ion exchange column

The model consists of 30 effective plates.

Each plate corresponds to certain amount of the exchanger. The material in each plate is surrounded by the solution. Two single-charged ions A and B are exchanged.

A batch equilibrium distribution of ions between the exchanger and solution is calculated for each effective plate in each step.

The column performance is represented by a series of discrete actions (shifts or discrete movements of the solution). At the step number n, each effective plate is equilibrated with surrounding solution. A solution shift is considered after the equilibration, i.e., at step number n+1, the solution moves from one plate to the next one along the column. After the shift, equilibria are established again.

Concluding: continuous flow of the solution is modelled as a number of discrete shifts along a number of batch ion exchange reactors (effective plates).

K is the ion exchange constant, see equation (11.1) in the book.
Capacity is the total capacity of one effective plate.
Volume is volume of the solution surrounding one effective plate.
[A] is concentration of the ion A in the feed solution.
[B] is concentration of the ion B in the feed solution.

Graphical representation is:

Left column represents the ratio between concentrations of A (red) and B (blue) ions in the solution located between the exchanger beads.
Right column represents the ratio between contents of A (red) and B (blue) ions in the exchanger.
Each square represents one effective plate in the column.
The square at top-left corner represents the feed solution composition.
The square at bottom-left corner represents the effluent.

One step can be executed pressing the button [+1 step]. Several steps at once can be executed pressing the button [+ steps]. The number of steps to perform can be introduced in the text field above the button. To start a new experiment, change the characteristics and press the button [reset]. The column will be reset to A form equilibrated with solution containing only A.