If we want to use hard water in textile dye processing first off all we need to remove the hardness of water. There are two types of hardness:
(1)Temporary hardness
(2) permanent hardness.
Temporary hardness:
1. Ca(HCO3)2 + Ca(OH)2 → 2CaCO3 ↓ +2H2O
2. Mg(HCO3)2 + 2Ca(OH)2 → 2MgCO3 +2H2O
MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3
Permanent Hardness:
- CaSO4 + Na2CO3 → CaCO3+ Na2SO4
- 2. MgSO4 + Na2CO3 → MgCO3+ Na2SO4
MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3
Temporary hardness is remove by both boiling and temporary treatment and permanent hardness remove by the chemical treatment.