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Measurement and Modelling of Pm Sorption onto TiO2 and goethite

Anna-Maria Jakobsson (Institutionen för material- och ytkemi, Kärnkemi) ; Yngve Albinsson (Institutionen för material- och ytkemi, Kärnkemi) ; R.S. Rundberg
Radiochimica Acta (0033-8230 ). Vol. 92 (2004), p. 683-689 .
[Artikel, refereegranskad vetenskaplig]

The sorption of Pm (1 x 10(-9) M) onto TiO2 and goethite has been studied as a function of pH and Ionic strength (0.01, 0.1 M NaClO4) at ambient temperature under N-2 atmosphere. For both minerals studied there is no effect of the different ionic strengths and the sorption (log K-a vs. pH) increases with a slope of similar to2. At the same pH sorption is lower on the more positively (or less negatively) charged goethite (pH(pzc) = 8.4) than on the TiO2 (pH(pzc) = 6.2). A comparison to other trivalent cations sorbed on different substrates (made by extracting values from %-sorbed curves and calculating these to K-a) indicate a similar pH-dependence. The results have been fitted using a 1-pK basic Stern model with FITEQL [1]. An a priori restriction was that only one sorption reaction stoichiometry at a time was to be used to keep the number of parameters as small as possible. Outersphere and mono-, bi- and tri-dentate inner-sphere complexes were fitted. For each fit the value of the capacitance was varied to find the value that provided the best fit. Two different site densities were used: 1 site/nm(2) and 2.31 sites/nm(2). For the low site density the reaction which provides the best tit was: drop SOH0.5- + Pm+3 <----> drop SOHPm2.5+ for both minerals. At the high site density the same reaction fits for TiO2 while there are several reactions that are equivalent in the fit for goethite.

Nyckelord: Pm; sorption; TiO2; goethite; surface complexation modelling, SURFACE COMPLEXATION; ACID-BASE; FLUORESCENCE SPECTROSCOPY; METAL (HYDR)OXIDES; SOLUTION INTERFACE; WATER INTERFACE; CATION SORPTION; IONIC-STRENGTH; ADSORPTION; ALUMINA



Denna post skapades 2008-01-17.
CPL Pubid: 67382

 

Institutioner (Chalmers)

Institutionen för material- och ytkemi, Kärnkemi (2002-2004)

Ämnesområden

Kemi

Chalmers infrastruktur