Behaviour of uranium in iron-bearing permeable reactive barriers:: investigation with 237U as a radioindicator

This study was undertaken to investigate the long-term performance of elemental iron as reactive material for the removal of uranium in passive groundwater remediation systems. By using U-237 as a radioindicator it was possible to track the movement of the contamination front through a test column without taking samples or dismantling the apparatus. The stoichiometric ratio between uranium and iron was found to be 1:(1390+/-62). The reaction between iron and uranium is of pseudo first-order kinetics and the rate constant was measured to be (1.1+/-0.09) x 10(-3) s(-1). These data enable the calculation of ideal lifetime for permeable reactive barriers (PRB) using iron for uranium removal neglecting hydrological factors that may impair the function of PRBs. (C) 2002 Elsevier Science B.V. All rights reserved.