| 摘要 |
In the regeneration of strongly acid cation exchange resins with sulphuric acid, the regeneration solution containing sulphuric acid is passed first over an anion exchange resin containing chloride and/or nitrate ions and then over the cation exchange resins. The regenerating solution contains at least 25 g. of sulphuric acid per litre. Of the total ion charge contained in the anion exchange resin, at least 30% is in the form of chloride and/or nitrate ions and preferably less than 20% is in the form of hydroxyl, carbonate and silicic acid ions. By such regeneration of cation exchange resins, precipitation of calcium sulphate may be avoided in desalting plants. Examples of both cation and anion exchange resin materials are listed in the Specification. |
