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Electrokinetic generation of reactive iron-rich barriers in wet sediments: implications for contaminated land management

Published online by Cambridge University Press:  05 July 2018

D. W. S. Faulkner ,
L. Hopkinson  and
A. B. Cundy
D. W. S. Faulkner*
Affiliation:
Division of Civil Engineering and Geology, University of Brighton, Brighton BN2 4GJ, UK
L. Hopkinson
Affiliation:
Division of Civil Engineering and Geology, University of Brighton, Brighton BN2 4GJ, UK
A. B. Cundy
Affiliation:
Centre for Environmental Research, University of Sussex, Brighton BN1 9QJ, UK
*
*E-mail: [email protected]
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Abstract

Here we describe preliminary research into the in situ electrokinetic generation of continuous iron-rich precipitates to act as sub-surface barriers for the containment of contaminated sites. This is achieved using sacrificial iron electrodes emplaced either side of a soil/sediment mass to introduce iron into the system, and their dissolution and re-precipitation under the influence of an applied (DC) electric field. Continuous vertical and horizontal iron-rich bands (up to 2 cm thick) have been generated over a timescale of 300—500 h, at voltages of <5 V with an electrode separation of between 15 and 30 cm. The thickness of the iron-rich band increases as the applied voltage is increased. Geotechnical tests in sand indicate that the iron-rich band produced is practically impervious (coefficient of permeability of 10—9 ms—1 or less), and has significant mechanical strength (unconfined compressive strength of 10.8 N mm—2). By monitoring the current, the integrity of the iron-rich band may be assessed, and by continued application of current, the barrier may 'self heal'. The iron-rich barrier is composed of amorphous iron, goethite, lepidocrocite, maghemite and native iron.

Keywords

electrokineticshorizontal barriersironcontaminated land
Type
Research Article
Information
Mineralogical Magazine , Volume 69 , Issue 5 , October 2005 , pp. 749 - 757
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2005

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