Towards an understanding of the sorption of U(V) and Se(IV) on sodium bentonite

被引:65
作者
Boult, KA
Cowper, MM
Heath, TG [1 ]
Sato, H
Shibutani, T
Yui, M
机构
[1] AEA Technol, Didcot, Oxon, England
[2] Tokai Works, Power Reactor & Nucl Fuel Dev, Ibaraki, Osaka, Japan
关键词
sorption; radionuclides; selenium; uranium; bentonite; montmorillonite;
D O I
10.1016/S0169-7722(98)00122-3
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The sorption behaviour of uranium(VI) and selenium(IV) on a purified bentonite sample has been investigated and the results compared with those for sorption onto the unpurified material and goethite. Batch sorption data for U(VI) on purified bentonite show strong sorption in the pH range 5 to 8 (R-d > 10(4) cm(3) g(-1)). Outside this range the sorption decreases although the R-d remains above 10(3) cm(3) g(-1) across the pH range studied. U(VI) sorption was also found to decrease rapidly with increasing carbonate concentration. Thermodynamic modelling of the data indicates that sorption at low pH may be due to an ion-exchange process, whereas above pH 5 surface complexation dominates. The sorption of Se(IV) on purified bentonite was found to be significant only below pH 7. Sorption of Se(IV) on goethite showed a strong dependency on pH; with strong sorption below pH 8, and a sharp decrease in sorption above pH 8. Sorption of Se(IV) onto the smectite component of impure bentonite is therefore only likely to be significant at low pH and sorption is dominated by a goethite-like surface of an iron constituent mineral above pH 5. (C) 1998 Published by Elsevier Science B.V. All rights reserved.
引用
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页码:141 / 150
页数:10
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