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Applied and Environmental Soil Science
Volume 2014 (2014), Article ID 462514, 6 pages
http://dx.doi.org/10.1155/2014/462514
Research Article

Uranium Leaching from Contaminated Soil Utilizing Rhamnolipid, EDTA, and Citric Acid

1Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ, USA
2Deerpoint Group, Inc., Fresno, CA, USA

Received 10 April 2014; Accepted 3 July 2014; Published 22 July 2014

Academic Editor: Rafael Clemente

Copyright © 2014 Sara Asselin and Jani C. Ingram. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Biosurfactants have recently gained attention as “green” agents that can be used to enhance the remediation of heavy metals and some organic matter in contaminated soils. The overall objective of this paper was to investigate rhamnolipid, a microbial produced biosurfactant, and its ability to leach uranium present in contaminated soil from an abandoned mine site. Soil samples were collected from two locations in northern Arizona: Cameron (site of open pit mining) and Leupp (control—no mining). The approach taken was to first determine the total uranium content in each soil using a hydrofluoric acid digestion, then comparing the amount of metal removed by rhamnolipid to other chelating agents EDTA and citric acid, and finally determining the amount of soluble metal in the soil matrix using a sequential extraction. Results suggested a complex system for metal removal from soil utilizing rhamnolipid. It was determined that rhamnolipid at a concentration of 150 μM was as effective as EDTA but not as effective as citric acid for the removal of soluble uranium. However, the rhamnolipid was only slightly better at removing uranium from the mining soil compared to a purified water control. Overall, this study demonstrated that rhamnolipid ability to remove uranium from contaminated soil is comparable to EDTA and to a lesser extent citric acid, but, for the soils investigated, it is not significantly better than a simple water wash.