Effects of process variables on reaction mechanisms responsible for ADUN hydrolysis, precipitation, and gelation in the internal gelation gel-sphere process
Studies were conducted that indicate five chemical reactions are important during acid-deficient uranyl nitrate (ADUN) hydrolysis and precipitation in the internal gelation process for microsphere preparation. Experiments performed to determine pH profiles during urania gelation in conjunction with hexamethylenetetramine (HMTA) decomposition experiments were useful in defining important characteristics of these reactions and in determining process variables that affect reaction rates as well as pH regions in which ADUN precipitates. These variables are the nitrate-to-uranium and the HMTA-to-uranium mol ratios, the uranium concentration, and the gel formation temperature. The influence of these process variables on the solution pH and precipitation reactions is discussed. The results of this study suggest that increased knowledge of these reactions and their kinetics should make it possible to better understand and control microsphere characteristics, which can vary widely with variations in process variables. It is this inherent capability to produce metal oxide microspheres with precise properties that makes internal gelation processes uniquely useful for many applications. 19 references, 15 figures, 2 tables.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 707319
- Report Number(s):
- ORNL/TM-8818; ON: TI84027011
- Resource Relation:
- Other Information: PBD: Apr 1984
- Country of Publication:
- United States
- Language:
- English
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