Evaluation of degree of readsorption of radionuclides during sequential extraction in soil: comparison between batch and dynamic extraction systems.

Roongrat Petersen, Elo Harald Hansen, Xiaolin Hou

Research output: Contribution to conferencePaperResearchpeer-review

Abstract

Sequential extraction techniques have been widely used to fractionate metals in solid samples (soils, sediments, solid wastes, etc.) due to their leachability. The results are useful for obtaining information about bioavailability, potential mobility and transport of element in natural environments. However, the techniques have an important problem with redistribution as a result of readsorption of dissolved analytes onto the remaining solids phases during extraction. Many authors have demonstrated the readsorption problem and inaccuracy from it. In our previous work, a dynamic extraction system developed in our laboratory for heavy metal fractionation has shown the reduction of readsorption problem in comparison with the batch techniques. Moreover, the system shows many advantages over the batch system such as speed of extraction, simple procedure, fully automatic, less risk of contamination and less dependency on extraction conditions. Therefore, it is thought that the dynamic extraction system would show less readsorption problem for radionuclides. This work emphasizes on the study of readsorption of Pu and Am when both batch and dynamic extraction systems are employed. For the dynamic extraction procedure, an extraction column (cylindrical shape, volume ca. 3 mL) is designed and implemented into the conduit of sequential injection setup. The sample is filled in the extraction column and different extracting reagents are pumped sequentially through the column by mean of the syringe pump. In this study, a method of standard addition into extractants was used to evaluate readsorption phenomena in the modified standard, measurement and testing programme's (SM&T) sequential extraction scheme. The result showed that the dynamic extraction system gave similar degree of readsorption for both Pu and Am compared with the batch system. Step-wise tests indicated that 80% of Pu and over 90% of Am extracted from exchangeable fraction was readsorbed. And over 95% of Pu and Am from acid soluble and reducible fractions were readsorbed. Pu and Am mainly readsorbed to oxidizable fraction or organic matter phase even at low organic content (2.5 wt.%).
Original languageEnglish
Publication date2006
Publication statusPublished - 2006
EventSeminar for young scientists in the fields of radiophysics, radiochemistry, radioecology and radiation protection and related fields - Helsinki, Finland
Duration: 1 Jan 2006 → …
Conference number: 1

Conference

ConferenceSeminar for young scientists in the fields of radiophysics, radiochemistry, radioecology and radiation protection and related fields
Number1
CityHelsinki, Finland
Period01/01/2006 → …

Cite this