Measurement and modeling of Th sorption onto TiO{sub 2}

Journal Article · Wed Dec 15 04:00:00 EST 1999 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1999.6535· OSTI ID:20013631

Jakobsson, A M

The sorption and desorption of Th onto TiO{sub 2} (10 g/L) was studied as a function of pH (1--11), ionic strength (0.005--0.1 M NaCl, NaClO{sub 4}), thorium concentration (from 1 x 10{sup {minus}9} to 3 x 10{sup {minus}2} M), and carbonate concentration (up to 10{sup {minus}2} M) using {sup 234}Th tracer. The results indicate the reversible formation of an inner sphere complex with a strong pH dependence. No effect on the carbonate on sorption could be measured in the pH range investigated (5--10.5). The data were fitted with five different conceptual models (constant capacitance, diffuse layer, Stern, triple layer, and a nonelectrostatic model) using FITEQL. Different hydroxy complex surface reactions were tried, one at a time, varying the site density (1--12 sites/nm{sup 2}). The reaction that provided the best fit depended strongly on the surface site density and the model used. To be able to fit a reaction to the pH-dependent data with the compact layer models, the effect of the electrostatic term had to be decreased by decreasing the site density below 5 sites/nm{sup 2}. None of the electrostatic models could be used to fit all of the isotherm data. The nonelectrostatic model could be used to reasonably fit both the pH-dependent and isotherm data.

• Research Organization: Chalmers Univ. of Technology, Goeteborg (SE)
• OSTI ID: 20013631
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 2 Vol. 220; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CARBONATES
PH VALUE
RADIONUCLIDE MIGRATION
SORPTION
SORPTIVE PROPERTIES
THORIUM
TITANIUM OXIDES