GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 79-5
Presentation Time: 9:00 AM

TRANSFORMATION OF THE URANYL PEROXIDE MINERAL STUDTITE, [(UO2)(O2)(H2O)2](H2O)2, TO SOLUBLE NANOSCALE CAGE CLUSTERS


LOBECK, Haylie L., Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, ISNER, Jordan K., Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556 and BURNS, Peter C., Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 301 Stinson-Remick Hall, Notre Dame, IN 46556

Understanding the conditions for the formation of solid and aqueous uranyl peroxide species is important in the nuclear fuel cycle and for modeling the fate and transport of uranium in the environment. A study of the transformation between the uranyl peroxide mineral studtite [(UO2)(O2)(H2O)2]H2O2 and uranyl peroxide nanocluster U28 [(UO2)(O2)1.5]2828- under varying free peroxide concentration (0.01 M – 1.0 M) and alkaline pH conditions (7 – 11) was performed and the resulting uranyl peroxide species were observed under each condition. Nanoclusters were only detected in solution where free peroxide was added and there was enough base (tetraethylammonium hydroxide) to increase the pH of the solution above 9 and have enough cations to counterbalance the negative charge of the U28. The O2(g) produced from the formation of the peroxide bridges in the nanoclusters was measured and it is hypothesized the peroxide bridges originate from a mixture of free peroxide in solution and the original peroxide bonds in the studtite starting material.