Department of Chemistry and Biochemistry, The Florida State University Tallahassee, FL-32306, USA; On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085, India
Department of Chemistry and Biochemistry, The Florida State University Tallahassee, FL-32306, USA
Sorption behavior of europium, Eu3+, on SiO2 . xH2O (silica gel) has been investigated as a function of time, the amount of silica gel, Eu3+ concentration, the ionic strength, and pH (in absence and in presence of carbonate). The sorption data were fitted to Freundlich,
Langmuir and Dubinin-Radushkevich (D-R) isotherms. The sorption capacity of silica gel was determined to be in the range of
(2.62-8.00) . 10-7 mol/g at pH 5.30±0.05 and 0.20M NaClO4. The mean energy of sorption was calculated to be 13.50±0.05 kJ/mol from the D-R isotherm, suggesting the involvement of
ion-exchange reactions in the sorption process. Sorption of Eu3+ decreased with increased ionic strength. A gradual decrease in pH with increased ionic strength supports the involvement
of an ion-exchange mechanism in the sorption process. The diffusion coefficient of Eu3+ ion on silica gel was calculated as (3.98±0.12) . 10-13 m2 . s-1 under the particle diffusion-controlled conditions.