Photochemical reduction of U(VI) in aqueous solution in the presence of 2-propanol

VANESA N. SALOMONE; JORGE M. MEICHTRY; GUILLERMO SCHINELLI; ANA G. LEYVA; MARTA I. LITTER

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2014 vol. 277 p. 19 - 26

1010-6030

The efficiency of the photochemical reduction of uranyl (UO22+) (0.25 mM, pH 3) was analyzed in the absence and in the presence of 2-propanol (2-PrOH), evaluating the effect of anions (nitrate, acetate and perchlorate) and the use of quartz and glass photoreactors. Higher removals were observed with the quartz photoreactor; the best system was that starting from uranyl nitrate, where a 90% UO22 removal was attained after 15 min irradiation. In the absence of 2-PrOH, the acetate system was the only one where some U(VI) removal was observed (15% after 15 min in the quartz photoreactor) but, in the presence of the alcohol, the acetate system was the least reactive. In the irradiated uranyl systems, nitrate and acetate were consumed during the reaction, causing important effects on the conversion, while perchlorate was inactive. Uranium was removed from the system as a solid residue in the case of nitrate- (as U(IV)) and perchlorate-containing systems (as U(VI)), while it remained in solution in the case of the acetate systems. Mechanisms are proposed for the different conditions. The importance of nitrate as a reducing agent of uranium species has not been previously reported. The use of uranyl nitrate and short-near UV-vis light seems to be the most advisable way of removing uranyl from solutions in the form of a stable precipitate.