Purification of conc. HCl              

One of the earlier, rather unique, applications for metal ion removal is that of iron removal from concentrated hydrochloric acid. In concentrated hydrochloric acid, iron is known to be present as an anionic chloride complex, and strong base anionic resins have been used success successfully to remove this complex. Since at low chloride concentration the anionic complex does not exist the iron can be eluted from the resin by rinsing the bed with water.