Aside from its use to purify drinking water the technique is widely applied for purification and separation of a variety of industrially and medicinally.
Ion exchange water softener diagram.
A standard whole house water softener works on the principle of ion exchange called cation exchange it conditions or softens hard water by substituting sodium chloride salt for hard minerals such as calcium magnesium and iron.
In the ion exchange process sodium ions are used to coat an exchange medium in the softener.
As hard water passes through a softener the calcium and magnesium trade places with sodium ions figure 1.
The exchange is made possible because the minerals are ionic in nature which means they have an electrical charge.
In the resin the hardness ions are exchanged with the sodium and the sodium diffuses into the bulk water solution.
The exchange medium can be natural zeolites or synthetic resin beads that resemble wet sand.
Sodium zeolite softening is the most widely applied use of ion exchange.
The hardness ions ca and mg move into the resin beads and each of these divalent.
Rohm and haas ion exchange ion exchange introduction 4 fd sep 2008 to soften water you take a cation exchange resin on which the mobile ion inside the beads is sodium na and you pass the hard water through a column filled with the sodium form resin.
The ion exchange process is based on the fact that like charges repel one another and opposite charges attract.
In zeolite softening water containing scale forming ions such as calcium and magnesium passes through a resin bed containing sac resin in the sodium form.
An expert explanation and diagram of how a conventional water softener softens hard water.