title: Remediation of soils contaminated with particulate depleted uranium by multi stage chemical extraction.
abstract: Contamination of soils with depleted uranium (DU) from munitions firing occurs in conflict zones and at test firing sites. This study reports the development of a chemical extraction methodology for remediation of soils contaminated with particulate DU. Uranium phases in soils from two sites at a UK firing range, MOD Eskmeals, were characterised by electron microscopy and sequential extraction. Uranium rich particles with characteristic spherical morphologies were observed in soils, consistent with other instances of DU munitions contamination. Batch extraction efficiencies for aqueous ammonium bicarbonate (42-50% total DU extracted), citric acid (30-42% total DU) and sulphuric acid (13-19% total DU) were evaluated. Characterisation of residues from bicarbonate-treated soils by synchrotron microfocus X-ray diffraction and X-ray absorption spectroscopy revealed partially leached U(IV)-oxide particles and some secondary uranyl-carbonate phases. Based on these data, a multi-stage extraction scheme was developed utilising leaching in ammonium bicarbonate followed by citric acid to dissolve secondary carbonate species. Site specific U extraction was improved to 68-87% total U by the application of this methodology, potentially providing a route to efficient DU decontamination using low cost, environmentally compatible reagents.
authors.affiliation: Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, UK; Centre for Radiochemistry Research, School of Chemistry, The University of Manchester, UK.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Crean
authors.forename: Francis R
authors.initials: FR
authors.lastname: Livens
authors.forename: Mustafa
authors.initials: M
authors.lastname: Sajih
authors.forename: Martin C
authors.initials: MC
authors.lastname: Stennett
authors.forename: Daniel
authors.initials: D
authors.lastname: Grolimund
authors.forename: Camelia N
authors.initials: CN
authors.lastname: Borca
authors.forename: Neil C
authors.initials: NC
authors.lastname: Hyatt
mesh_terms: D001345:Autoradiography; D001639:Bicarbonates / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D004867:Equipment Design; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry; D010316:Particle Size; D012987:Soil; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014501:Uranium / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
chemical_list: D001639:Bicarbonates; D010087:Oxides; D012987:Soil; D012990:Soil Pollutants, Radioactive; D019343:Citric Acid; C027043:ammonium bicarbonate; D014501:Uranium
keywords: Chemical extraction; Depleted uranium; Micro-focus X-ray diffraction; Remediation