The heats of adsorption of metal cations on silica gel with covalently fixed polyaspartic acid

The heat effects of adsorption of ammonium and alkali, alkaline-earth, and transition metal cations on silica gel with covalently fixed polyaspartic acid were considered. The heats of adsorption of ammonium and alkali metal cations were determined with the use of 0.2 and 0.75 mM solutions of perchloric acid as eluents. The heats of adsorption of ammonium, and alkali metal cations on silica gel with covalently fixed polyaspartic acid with the use of a 0.2 mM solution of perchloric acid as eluent and ammonium, alkali, and alkaline-earth metal cations on Universal Cation and Selekton K adsorbents were determined with the use of a 2.75 mM solution of nitric acid as eluent. The retention mechanism was shown to be dominated by ion exchange on all adsorbents studied. Three types of dependences of cation retention on the temperature of the chromatographic column were found.