Extraction of Palladium from Nitric Acid by Diamides of Di-picolinic Acid
- 'V.G. Khlopin Radium Institute', 28, 2nd Mirinskiy Ave, St.-Petersburg, 194021 (Russian Federation)
The most complicated and urgent problem of atomic industry consists in the safe isolation and storage of radioactive wastes. The long-lived radionuclides presented in high-level liquid wastes (HLLW) pose a potential threat to environment for hundreds and thousands of years. One of the possible ways to reduce the danger of HLLW storages is concerned with treatment of HLLW intended to recovery of long-lived radionuclides and their partitioning into separate fractions. The separation of the most hazardous radionuclides (like transplutonium elements (TPE)) to the individual fraction of low volume leads to decrease of the total volume of HLLW and therefore to decrease of solidified waste storage costs. It should be noted that only in the case of reprocessing it can be possible to recover individual radionuclides (or their fractions) into separate flows with further special approach to each of them. Partitioning of different HLLW is under investigation in many countries now. Numerous processes for recovery of Cs, Sr, TPE and REE have been already developed and tested. At the same time partitioning is only the first step on the road to the following synthesis of materials providing the safe storage of long-lived radionuclides over many thousands of years. The metallic palladium contained in HLLW seems to be a promising material for producing of matrices for incorporation of radioactive wastes. Different methods for palladium recovery have been investigated: reductive precipitation, electrochemical precipitation, sorption and extraction. Of prime importance are extraction methods. Phosphine oxides, carbamoyl-phosphine oxides, crown-ethers, oximes, sulfides and some other compounds were proposed as extractants towards palladium from nitric acid media. It is reasonable to recover palladium into individual fraction during waste partitioning. Diamides of malonic, di-glycolic and pyridine-dicarboxylic (di-picolinic) acids are intensively investigated as extractants for HLLW partitioning. The data on palladium extraction by amides of pyridinecarboxylic acids from HCl medium are contradictory. It was shown that ethers of pyridine-3,5-dicarboxylic acid effectively recover palladium; at the same time the data given testify that palladium is effectively extracted by diamides of malonic and di-glycolic acids, while amides of di-picolinic acid (solution of N,N'-dimethyl-N,N'-diphenyl diamide of di-picolinic acid in chloroform) do not practically extract palladium from HCl solutions. It was found in our previous works that the use of polar fluorinated diluents instead of chloroform increases the extraction ability of diamides of di-picolinic acid towards americium and europium. The main goal of the present work was to investigate the palladium extraction from nitric acid by solutions of diamides of di-picolinic acid in meta-nitro-benzo-trifluoride (F-3) under conditions that were optimal for Am recovery from HLLW. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 20979775
- Resource Relation:
- Conference: Advanced nuclear fuel cycles and systems (GLOBAL 2007), Boise - Idaho (United States), 9-13 Sep 2007; Other Information: Country of input: France; 22 refs; Related Information: In: Proceedings of GLOBAL 2007 conference on advanced nuclear fuel cycles and systems, 1873 pages.
- Country of Publication:
- United States
- Language:
- English
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