Approaching Zero Discharge in Uranium Reprocessing:  Photochemical Reduction of Uranyl

We have studied the photochemical reduction of uranyl to generate UO2 without hydrogen reduction. Formate and oxalate were examined as potential reductants that only lead to CO2 production as a side product. Despite the similar nature of the two reductants, the mechanism for quenching the uranyl exc...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 2001-02, Vol.35 (3), p.547-551
Main Authors: McCleskey, T. Mark, Foreman, Trudi M, Hallman, Erin E, Burns, Carol J, Sauer, Nancy N
Format: Article
Language:English
Subjects:
Applied sciences
Carbon Monoxide - chemistry
Chemistry
Environmental impact
Exact sciences and technology
Hydrogen-Ion Concentration
Oxidation-Reduction
Photochemistry
Pollution
Radioactive Waste
Radioactive wastes
Refuse Disposal - methods
Uranium
Uranium - chemistry
Waste disposal
Wastes
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We have studied the photochemical reduction of uranyl to generate UO2 without hydrogen reduction. Formate and oxalate were examined as potential reductants that only lead to CO2 production as a side product. Despite the similar nature of the two reductants, the mechanism for quenching the uranyl excited-state changes drastically and leads to dramatically different chemistry at low pH. Oxalate quenches by unimolecular electron transfer and formate quenches by H-atom abstraction. Because of the change in mechanism, photochemical reduction of uranyl with formate works with high efficiency at low pH while photolysis in the presence of oxalate leads to the generation of CO and no net uranyl reduction. Photochemical reduction of uranyl with formate at low pH leads to U(IV) in solution that can then be precipitated as UO2 by simply raising the pH with yields as high as 99.992%.
ISSN:0013-936X
1520-5851
DOI:10.1021/es001078i