Ammonium Salts of the Heteropolyacids as Cation Exchangers

Abstract

Terlet and Briau¹ have found that variable amounts of the ammonium ions in an ammonium phosphomolybdate precipitate may be displaced by potassium ions, and to a lesser extent by sodium ions, when the precipitate is washed with neutral potassium nitrate or sodium sulphate solutions. These observations have been confirmed by Gisiger² and by Thistle-thwaite³, who have found that approximately two of the three ammonium ions are exchanged for potassium.