Process for the regeneration of ion exchanger substances

Abstract

Abstract 675,253. Electrolytic regeneration of ionexchange materials. RAFFINERIE TIRLEMONTOISE SOC. ANON. Aug. 3, 1950 [Sept. 12, 1949], No. 19361/50. Class 41. [Also in Group I] Ion - exchange materials which have been used for example for the purification of sugar juices are regenerated by being inserted between an anodic halfcell and a cathodic halfcell of an electrolysis apparatus which is then connected to a source of continuous electric current. In the case of a cation-exchange material 1 the anolyte 4 is water acidulated with, e.g. sulphuric acid, or is a solution of a salt, e.g. a sulphate, in water. The catholyte 5, may be the same as the anolyte, or water. During the electrolysis sulphate ions migrate to the anode 2 where sulphuric acid is re-formed and oxygen is evolved at 9, while hydrogen ions pass, on their way to the cathode, into the cationexchange material 1 displacing from it cations, e.g. alkali metal cations, incorporated in it during the purifying step. These instead of the hydrogen ions, migrate to the cathode 3 where, if the catholyte is water, a solution of alkali metal hydroxide is formed and hydrogen is evolved. In the case of regeneration of an anion-exchange material the catholyte 5 is a solution in water of a hydroxide, preferably an alkaline hydroxide, e.g. caustic soda, or of a salt, e.g. a sodium salt. During electrolysis sodium ions migrate, to the cathode 3 reforming sodium hydroxide with evolution of hydrogen, while hydroxyl ions displace anions from the material 1, the displaced anions reacting with the anode 2 or anolyte 4. In Fig. 1 (not shown), beds of .ion-exchange material are interposed between two outer anode chambers and a single common cathode chamber in the centre; in this case both beds must be of the same kind-cation-exchanging or anion-exchanging. Aqueous solutions of alkaline hydroxides produced during regeneration of cation-exchange materials may be used for regeneration of anion-exchange materials.

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