Sorption of Eu(III) on a Natural Hematite: Application of a Surface Complexation Model

✍ Scribed by Thomas Rabung; Horst Geckeis; Jae-Il Kim; Horst Philipp Beck

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 185 KB
• Volume: 208
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5788

✦ Synopsis

The solid/water interface reaction is investigated for the sorption of the Eu 3؉ ion onto a well-characterized natural hematite at pH <6 in 0.1 mol/L NaClO 4 . Sorption isotherms are determined at different pH. The sorption of Eu 3؉ onto hematite at coverages <1% of the surface hydroxyl groups follows the ideal Nernst behavior and can be interpreted in terms of the surface complexation by the following equilibrium reaction:

). Complexation constants are calculated by either graphically interpretating the sorption isotherms or fitting the data using the code FITEQL. At higher surface coverages a deviation from the Nernst behavior is observed which can be described satisfactorily by a two-site surface complexation model, taking into account the lateral electrostatic interaction of surface-bound Eu(III): 'YOH ؉ Eu 3؉ N 'YOEu 2؉ ؉ H ؉ (log K y int ‫؍‬ ؊0.82 ؎ 0.11). The experimental results are compared with data published in the literature, and the interpretation of sorption isotherms with regard to the sorption mechanisms is critically discussed.