Paper Details
Bibliographic Data:
| Code: |
SMS85 |
| Paper Type: |
Article |
| Author(s): |
Sanchez AL, Murray JW, Sibley TH |
| Title: |
The adsorption of plutonium IV and V on goethite |
| Journal: |
Geochimica et Cosmochimica Acta
Volume: 49 Year: 1985 Pages: 2297-2307
ISSN-Print: 0016-7037; 0016-1258 |
| Internal Storage: |
V1230 |
| DOI: |
10.1016/0016-7037(85)90230-3 |
| Abstract: |
The adsorption of Pu(IV) and Pu(V) on goethite (αFeOOH) from NaNO3 solution shows distinct differences related to the different hydrolytic character of these two oxidation states. Under similar solution conditions, the adsorption edge of the more strongly hydrolyzable Pu(IV) occurs in the pH range 3 to 5 while that for Pu(V) is at pH 5 to 7. The adsorption edge for Pu(V) shifts with time to lower pH values and this appears to be due to the reduction of Pu(V) to Pu(IV) in the presence of the goethite surface. These results suggest that redox transformations may be an important aspect of Pu adsorption chemistry and the resulting scavenging of Pu from natural waters.
Increasing ionic strength (from 0.1 M to 3 M NaCl or NaNO3 and 0.03 M to 0.3 M Na2SO4) did not influence Pu(IV) or Pu(V) adsorption. In the presence of dissolved organic carbon (DOC), Pu(V) reduction to Pu(IV) occurred in solution. Pu(IV) adsorption on goethite decreased by 30% in the presence of 240 ppm natural DOC found in Soap Lake, Washington waters. Increasing concentrations of carbonate ligands decreased Pu(IV) and Pu(V) adsorption on goethite, with an alkalinity of 1000 meq/l totally inhibiting adsorption.
The Pu-goethite adsorption system provides the data base for developing a thermodynamic model of Pu interaction with an oxide surface and with dissolved ligands, using the MINEQL computer program. From the model calculations we determined equilibrium constants for the adsorption of Pu(IV) hydrolysis species. The model was then applied to Pu adsorption in carbonate media to see how the presence of CO3−2 could influence the mobility of Pu. The decrease in adsorption appears to be due to formation of a Pu-CO3 complex. Model calculations were used to predict what the adsorption curves would look like if Pu-CO3 complexes formed.
Increasing ionic strength (from 0.1 M to 3 M NaCl or NaNO3 and 0.03 M to 0.3 M Na2SO4,) did not influence Pu(IV) or Pu(V) adsorption. In the presence of dissolved organic carbon (DOC), Pu(V) reduction to Pu(IV) occursed in solution. Pu(IV) adsorption on goethite decteased by 30% in the presence of 240 ppm natural DOC found in Soap Lake, Washington waters. Increasing concentrations of carbonate ligands decmased Pu(IV) and Pu(V) adsorption on goethite, with an alkalinity of 1000 meq/l totally inhibiting adsorption. The Pu-goethite adsorption system provides the data base for developing a thermodynamic model of Pu interaction with an oxide surface and with dissolved ligands, using the MINEQL computer program. From the model calculations we determined equilibrium constants for the adsorption of Pu(IV) hydrolysis species.
The model was then applied to Pu adsorption in carbonate media to see how the presence of CO3-2 could influence the mobility of Pu. The decrease in adsorption appears to be due to formation of a Pu-CO3 complex. Model calculations were used to predict what the adsorption curves would look like if Pu-CO3 complexes formed. |
| Comment: |
cited in [WAT01b], [ZB99], [PB95]; batch experiments; RAW_GRAPH (diagrammed raw data; % sorbed vs pH) |
Surface Area
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Site Density / Protolysis
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Complex Formation
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