Question

Zeolites are used to soften hard water through ion exchange. How does the crystal structure provide an explanation for ion-exchange properties of zeolites?

Answer 1

The interlinked and cage-like structure of zeolites has got porous structures which make it useful in many ways and one of the best uses of zeolites is in water softeners and water filters. Zeolites are hydrated aluminosilicate unit made from interlinked tetrahedra of alumina (AlO₄) and silica (SiO₄). In ion-exchange water softeners, for example, hard water (rich in calcium and magnesium ions) is piped through a column filled with sodium-containing zeolites. The zeolites exchange the calcium and magnesium ions by trapping them and release sodium ions in their place, so the water becomes softer but richer in sodium.