GB655555A - Improvements in or relating to the removal of anions from solution - Google Patents

Abstract

For removing acids of dissociation constant less than 10-5 from liquids (see Group I), a resin containing quaternary ammonium groups is prepared by refluxing 36 grams paraphenylene diamine with 74 c.cs. concentrated hydrochloric acid, 56 grams dicyandiamide and 50 c.cs. water for 18 hours. The product is then cooled and 48 grams paraformaldehyde added. When this is dissolved, 80 c.cs. ethylene dichloride and 60 c.cs. crotonaldehyde are added. On refluxing for 3/4 hour a gel is formed and dried at 110 DEG C. and then granulated to 20 to 40 mesh. Resins may also be prepared by methods described in Specifications 495,032, 634,943 and 655,554.ALSO:Acids of dissociation constant less than 10-5 are removed by passing the liquid through a bed of a synthetic resin which contains quaternary ammonium groups and which has been activated by caustic soda or the like, after "demineralising" the liquid by passing it through one or more pairs of hydrogen-ion-exchange and acid-removal beds to remove cations, and anions of acids of greater dissociation constant. The resin containing quaternary ammonium groups may be prepared by the member 32 is moved to engage either of methods described in Specifications 495,032, 634,943 and 655,554, [both in Group IV(a)]. Other examples are given in the Specification. Silica and phenol may be removed by the process, which is also applicable to carbon dioxide, but some of the latter is preferably removed after the demineralising step by blowing in air. According to the Provisional Specification, the resin containing quaternary ammonium groups may be activated or regenerated by sodium carbonate.