Sorption mechanism for Cs+, Co2+ and Eu3+ on amorphous zirconium silicate as cation exchanger

Zirconium silicate (ZrSi) as an inorganic ion exchanger was prepared from sodium meta-silicate (1 M) and zirconyl chloride (1 M) with molar ratio Zr/Si = 1:1. This inorganic ion exchanger has high chemical stability. The diffusion behaviors of Cs+, Co2+ and Eu3+ on the prepared ion exchanger have been studied under different conditions of particle sizes, reaction temperatures and drying temperatures. The experimental conditions were set to favor particle diffusion control condition only. The diffusion coefficient (D-i), activation energy (E-a), and entropy of activation (Delta S{*}) have been evaluated and compared with those reported for other inorganic and organic exchangers. The sorption isotherms were also investigated for Cs+, Co2+ and Eu3+ in the concentration range (5 x 10(-4)-10(-2) M) at different reaction temperatures (30, 45 and 65 +/- 1 degrees C). The values of thermodynamics parameters were determined and the sorption processes of the different metal ions were found exothermic. (C) 2007 Elsevier B.V All rights reserved.