Photocatalyzed deposition and concentration of soluble uranium(VI) from TiO2 suspensions

A reversible, photocatalytic reductive deposition of uranium on TiO(2) or Pt/TiO(2) occurs in deaerated U(VI)/EDTA solutions, accompanied by CO(2) released from the oxidation of EDTA. A maximum of 50-60% uranium(VI) is deposited and an ultimate CO(2) release equivalent to a single decarboxylation of EDTA was reached under our experiment conditions no matter how long the illumination time. In aerated solutions, no uranium deposited, but a large CO(2) release still occurred, presumably from EDTA mineralization. Nearly 100% of the deposited, reduced products from uranium(VI) on TiO(2). Pt/TiO(2) can be reoxidized and desorbed to regenerate dissolved uranium(VI) simply by solution exposure to air after illumination. The reductive deposition process can be repeated, indicating a potential cycle process. Modification of TiO(2) with platinum has only a slight influence on this reductive deposition of uranium on TiO(2). (C) 1999 Elsevier Science B.V. All rights reserved.