Alpha radiation induced formation of hydrogen peroxide in carbonate –bicarbonate media was followed by 13C NMR using dissolved [233UO2(13CO3)3]4- as the alpha source (Dalpha= 12.1 Gy/hr). Between the pH region between 5.9 and 11.6 hydrogen peroxide causes a varied speciation of the uranyl carbonates that is a function of the uranium, carbonate and the hydrogen peroxide concentrations. It is shown that the speciation of the peroxy carbonates (or other species) formed in solution by titration with hydrogen peroxide are common to those formed by hydrogen peroxide generated by radiolysis. The radiolysis experiment was carried out above pH = 9.96 to minimize the loss of 13CO2 over a 2800 hr period. Radiolytic generation of hydrogen peroxide was followed by formation of a uranyl peroxy carbonate complex and complex formation accelerated for about 1200 hours. Complex formation was observed to terminate at a concentration between 1x10-4 and 5x10-4 M. It is assumed that either a steady state H2O2 production rate was established in solution or that some limiting feature of the experiment was responsible for slowing the yield of product.
Revised: August 7, 2006 |
Published: May 1, 2006
Citation
McNamara B.K., L.A. Snow, C.Z. Soderquist, S.I. Sinkov, H.M. Cho, and J.I. Friese. 2006.The radiation induced chemistry of uranyl cation in aqueous carbonate –bicarbonate solutions as followed by NMR spectroscopy. In 2nd Symposium on Actinides - Basic Scienc, Applications and Technology held at the Materials Science Research Society Fall Meeting in Boston, Nov. 28-Dec. 1, 2005, Published in Actinides 2005, edited by Lynda Soderholm, 369-374. Warrendale, Pennsylvania:Materials Research Society.PNNL-SA-47948.