Brine purification
− Brine obtained from the is not pure sodium chloride, there are many impurities such
as
1. Iron
2. Calcium
3. Magnesium
− these would precipitate during the creation of sodium carbonate and cause the end
product to be impure
− to avoid this the brine is purified by first precipitating out these ions
1. with Carbonate (CO3
2-)
2. 2 2
3 3 ( ) ( ) ( ) Ca aq CO aq CaCO s + − +
3. with hydroxide (OH-)
4.
2
2
3
3
( ) 2 ( ) ( ) ( )
( ) 3 ( ) ( ) ( )
Mg aq OH aq MgOH s
Fe aq OH aq Fe OH s
+ −
+ −
+
+
5. Carbonate and hydroxide are used because most ions precipitate with them
− the precipitates are filtered off and the brine in fed into the ammonia saturator
hmm.... that didn't paste very well...
well go download my chem summary
