Some of the salt is made very pure and used for adding to food – but this isn’t anything like the biggest use. The most important use of salt is as a raw material for making other chemicals. Industry uses many sodium compounds. Most of them start life as salt which chemists have known as sodium chloride. The membrane Chlor-alkali process has become the leading process for caustic soda and chlorine production.
Chlor alkali process permits only the passage of sodium ions from the anode chamber to the cathode chamber and prevents the migration of hydroxyl ions to the anode chamber, which would reduce the current efficiency if it occurred.
Chlor-alkali process using the ion-exchange membrane is now recognized as the most energy-saving process for the production of chlorine and caustic alkali. Of all the manufacturing processes which use salt as raw material, the biggest is the manufacture of chlorine and sodium hydroxide by electrolysis. This is called the chlor-alkali process.