[appleseed]

im learning about water purification and i dont understand how an ion exchange resin works?
when the charged magnesium and calcium passes through the column , Na particles are kicked out of the column and replaced by the Mg and Ca ions.
But why will the positively charged Mg ions attract to the column?
are the columns cathodes so it attracts Mg ions?

Thankyou

[macman104]

It is the action of an equilibrium between the different ion concentrations.  The resin has a high sodium concentration and they exchange ions until an equilibrium is reached.  At least that is my understanding.

Ions of a high concentration diffuse to areas where the ions are in a low concentration.

You can then refresh the column by washing with a high sodium concentration solution, to establish a new equilibrium with more sodium on the resin.