Measurement and Modelling of Pm Sorption onto TiO2 and goethite
Artikel i vetenskaplig tidskrift, 2004

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.

ACID-BASE

Pm

TiO2

sorption

WATER INTERFACE

METAL (HYDR)OXIDES

CATION SORPTION

ALUMINA

FLUORESCENCE SPECTROSCOPY

SOLUTION INTERFACE

surface complexation modelling

goethite

SURFACE COMPLEXATION

ADSORPTION

IONIC-STRENGTH

Författare

Anna-Maria Jakobsson

Chalmers, Institutionen för material- och ytkemi, Kärnkemi

Yngve Albinsson

Chalmers, Institutionen för material- och ytkemi, Kärnkemi

R.S. Rundberg

Radiochimica Acta

0033-8230 (ISSN)

Vol. 92 683-689

Ämneskategorier

Kemi