SYNTHESIS AND ION-EXCHANGE PROPERTIES OF SILICA CHEMICALLY-MODIFIED WITH AMINOPHOSPHONIC ACID

The synthesis of a cation exchanger by conversion of 3-aminopropyl moi eties covalently attached to a silica surface to propylaminomethylphos phonic by reaction with sodium hypophosphite and formaldehyde is descr ibed. The ion-exchange properties of the prepared sorbent in the pH ra nge from 2.5 to 7.0 were evaluated by investigation of the retention o f different ionogenic organic molecules. The ion-exchange selectivity toward alkali and alkaline-earth and transition metals ions was estima ted. The effects of concentration of the nitric or perchloric acid, io nic strength and column temperature on the retention of cations were s tudied. The possibility of ion-chromatographic separation of a standar d mixture of seven allkaline-earth and transition metal ions on a shor t (50x4.6 mm) column packed with 10 mu m aminophosphonic-bonded silica using mineral acid solutions as eluents was demonstrated. (C) 1998 El sevier Science B.V. All rights reserved.