Chemicals Used In Precipitation Softening


When the PH of an aqueous solution is increased enough, metallic ions begin to precipitate out either as hydroxides or carbonates. The following chemicals are used in this chemical process known as precipitation softening:

CaO: Quick lime

Ca(OH)2: hydrated or slaked lime

Na2CO3: soda ash or sodium carbonate

CaSO4: calcium sulfate or gypsum

CaCl2: Calcium Chloride

NaOH: Caustic Soda

Alum (Al2[SO4]3) and Sodium Aluminate Na2Al2O4

Sulfides can be used to precipitate some heavy metals too


Compiled by Rami E. Kremesti