Open AccessPolymerization of Pu(IV) in aqueous nitric acid solutions
Author(s) -
L.M. Toth,
Henry L. Friedman,
M.M. Osborne
Publication year - 1980
Language(s) - English
Resource type - Reports
DOI - 10.2172/711701
Subject(s) - iodate , polymerization , nitric acid , chemistry , aqueous solution , reagent , polymer , inorganic chemistry , nitrate , uranyl nitrate , plutonium , precipitation , hydrolysis , nuclear chemistry , uranium , organic chemistry , materials science , physics , iodide , meteorology , metallurgy
The polymerization of Pu(IV) in aqueous nitric acid solutions has been studied spectrophotometrically both to establish the influence of large UO{sub 2}(NO{sub 3}){sub 2} concentrations on the polymerization rates and, more generally, to review the influence of the major parameters on the polymer reaction. Typically, experiments have been performed at 50{sup 0}C and with 0.05 M Pu in nitric acid solutions that vary in acidity from 0.07 to 0.4 M. An induction period usually precedes the polymer growth stage during which time nucleation of primary hydrolysis products occurs. Uranyl nitrate retards the polymerization reaction by approximately 35% in spite of the counteracting influence of the nitrate ions associated with this solute. The rate of polymer formation, expressed as d(percent polymer)/dt, has been shown to depend on the total plutonium concentration in reactions where the Pu(IV) concentration remained constant; and it is therefore suggested that the polymer reaction rate is not first order with respect to the concentration of plutonium as was previously thought. It has been shown further that accurate acid determinations on stock reagents are essential in order to obtain reliable polymerization experiments. Satisfactory procedures for these analyses did not exist, so appropriate modifications to the iodate precipitation methods were developed. The most ideal plutonium reagent material has been shown to be crystalline Pu(IV) nitrate because it can be added directly to acid solutions without the occurrence of unintentional hydrolysis reactions