Strongly Acidic Cation (SAC) Flashcards
What does SAC remove from water?
All metal cations including calcium and magnesium ions bound to bicarbonates
What functional groups do SAC resins have?
Sulphonic acid functional groups
What exchange ions are used in SAC resins for domestic water softeners?
Na+ or H+ ions
What is used to regenerate SAC resins when Na+ is the exchange ion?
Brine solutions
What is used to regenerate SAC resins when H+ is the exchange ion?
Strong acid solutions
Fill in the blank: The process for using Na+ as the exchange ion is: 2 resin-Na + (metal ion)2+ → (resin)2-metal ion + _______.
2Na+
Fill in the blank: The process for using H+ as the exchange ion is: 2 resin-H + (metal ion)2+ → (resin)2-metal ion + _______.
2H+
What is the order of cation removal by SAC when using H+ as the exchange ion?
- Fe
- Ca
- Mg
- K
- Na
- H
True or False: The use of H+ as the exchange ion leads to a significant drop in water pH.
True
What is the typical pH range of water after SAC treatment using H+ ions?
pH 2.5 - 3.5
What happens to carbonate ions after SAC treatment with H+ ions?
Converted to carbonic acid
What can be used to remove CO2 and water after SAC treatment?
Degassing tower or membrane degasser
When using Na+ as the exchange ion, what happens to the pH of the water?
Does not drop significantly
Which ions are exchanged for Na+ when SAC is used?
- Ca²+
- Mg²+
- Fe²+
- Mn²+
What may be necessary if the final Na+ levels in the water are too high?
Reverse osmosis
Why is SAC often used upstream of a reverse osmosis unit?
To prevent calcium from scaling the membrane
What happens if the resin is regenerated with KCl instead of NaCl?
Outlet will have equivalent potassium compounds
True or False: Bicarbonate is removed when using SAC.
False
What type of water can the treated water be used for if it is unsuitable for product water?
Process water for bottle washing/CIP and service water for steam raising
