HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Gadelle, F. Articles by Tokunaga, T. K. Search for Related Content PubMed PubMed Citation Articles by Gadelle, F. Articles by Tokunaga, T. K. GeoRef GeoRef Citation Agricola Articles by Gadelle, F. Articles by Tokunaga, T. K. Related Collections Water Quality Watershed and Landscape Processes Heavy Metals Water Pollution

TECHNICAL REPORT
HEAVY METALS IN THE ENVIRONMENT

Removal of Uranium(VI) from Contaminated Sediments by Surfactants

^a Lawrence Berkeley National Lab., MS 90-1116, 1 Cyclotron Road, Berkeley, CA 94720
^b Chevron Petroleum Technology Co., 6001 Bollinger Canyon Rd., San Ramon, CA 94583

Corresponding author (jmwan{at}lbl.gov)

Received for publication December 13, 1999. 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 mM, 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 H₂SO₄ 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.

Abbreviations: CB, carbonate–bicarbonate • CBD, citrate–bicarbonate–dithionite • CMC, critical micelle concentration • ICP–AES, inductively coupled plasma atomic emission spectroscopy • ICP–MS, inductively coupled plasma mass spectrometry • NTA, nitrilotriacetic acid • SDS, sodium dodecyl sulfate