If I want to use hard water for my textile dye processing, at first I need to make hard water into soft water
through different reactions for good results.
Water can be hard in two ways. They are:
1.Temporary hardness
2.permanent hardness.
For Temporary hardness:
Temporary hardness is caused by Calcium hydrogen carbonate (Ca(HCO3)2) or Magnesium hydrogen
carbonate (Mg(HCO3)2).
For making this Temporary water to soft water, we have to
boiling this water or make by using
calcium reaction like
1. Ca(HCO3)2 +
Ca(OH)2 → 2CaCO3 ↓ +2H2O
2. Mg(HCO3)2 + 2Ca(OH)2 →
2MgCO3 +2H2O
3. MgCO3 + Ca(OH)2 →
Mg(OH)2 + CaCO3
For Permanent hardness:
is caused by calcium sulfate (CaSO4)
or magnesium sulfate (MgSO4 ).
1.CaSO4 + Na2CO3 →
CaCO3+ Na2SO4
2.MgSO4 + Na2CO3 →
MgCO3+ Na2SO4
3.MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3
For above that we can see, temporary hardness of water can remove by
both boiling process and temporary treatment process but permanent hardness of
water can remove by the chemical
treatment process only.