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Removal of Uranium(VI) from Contaminated Sediments by Surfactants
Author(s) -
Gadelle Frederic,
Wan Jiamin,
Tokunaga Tetsu K.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.302470x
Subject(s) - sorption , desorption , chemistry , uranium , dissolution , environmental chemistry , soil water , soil contamination , pulmonary surfactant , environmental remediation , contamination , adsorption , geology , soil science , organic chemistry , biochemistry , materials science , metallurgy , ecology , biology
Uranium(VI) sorption onto a soil collected at the Melton Branch Watershed (Oak Ridge National Laboratory, TN) is strongly influenced by the pH of the soil solution and, to a lesser extent, by the presence of calcium, suggesting specific chemical interactions between U(VI) and the soil matrix. Batch experiments designed to evaluate factors controlling desorption indicate that two anionic surfactants, AOK and T77, at concentrations ranging from 60 to 200 m M , are most suitable for U(VI) removal from acidic soils such as the Oak Ridge sediment. These surfactants are very efficient solubilizing agents at low uranium concentrations: ca. 100% U(VI) removal for [U(VI)] o,sorbed = 10 −6 mol kg −1 At greater uranium concentrations (e.g., [U(VI)] o,sorbed = ca. 10 −5 mol kg −1 ), the desorption efficiency of the surfactant solutions increases with an increase in surfactant concentration and reaches a plateau of 75 to 80% of the U(VI) initially sorbed. The most probable mechanisms responsible for U(VI) desorption include cation exchange in the electric double layer surrounding the micelles and, to a lesser extent, dissolution of the soil matrix. Limitations associated with the surfactant treatment include loss of surfactants onto the soil (sorption) and greater affinity between U(VI) and the soil matrix at large soil to liquid ratios. Parallel experiments with H 2 SO 4 and carbonate–bicarbonate (CB) solutions indicate that these more conventional methods suffer from strong matrix dissolution with the acid and reduced desorption efficiency with CB due to the buffering capacity of the acidic soil.