ZEOLITE OR PERMUTIT PROCESS
Zeolites are naturally occuring hydrated sodium alumino silicate minerals. Na2O. Al2O3. xSiO2. yH2O where x = 2 to 10 and y = 2 to 6. Natural zeolites are nonporous. The synthetic form of zeolite is known as permutit. Synthetic zeolite is represented by Na2Ze. Synthetic zeolites are porous and have a jelly structure. They are prepared by heating together china clay, feldspar and soda ash. These zeolites have higher exchange capacity per unit weight than natural zeolites. In this synthetic zeolite process, the hard water is allowed to percolate through sodium zeolite. The sodium ions which are loosely held in Na2Ze are replaced by Ca2+ and Mg2+ ions present in the water. Process: In this process , the hard water is passed through a bed of sodium zeolite (Na2Ze). The hardness-causing ions (Ca2+, Mg2+) in hard water is replaced by loosely held sodium ions in zeolite bed. The outgoing soft water contains only sodium ions. Na2Ze + Ca(HCO3)2 --> CaZe + 2NaHCO3 Na2Ze + Mg(HCO3)2 -