Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds
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K. C. Pitchaiah
und
P. R. Vasudeva Rao
Abstract
In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO2) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO3. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO3 medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO2 containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.
©2014 Walter de Gruyter Berlin/Boston
Artikel in diesem Heft
- Frontmatter
- Preface
- Separation Science in Nuclear Technology in India
- Studies on extraction of actinides by unsymmetrical diamylbutyl phosphonate
- Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds
- Novel polymer inclusion membranes containing T2EHDGA as carrier extractant for actinide ion uptake from acidic feeds
- Studies on the feasibility of using completely incinerable reagents for the single-cycle separation of americium(III) from simulated high-level liquid waste
- Phosphonates as alternative to tributyl phosphate for the separation of actinides from fission products
- Actinides draw down process for pyrochemical reprocessing of spent metal fuel
- Spectroscopic investigations on sorption of uranium onto suspended bentonite: effects of pH, ionic strength and complexing anions
- Speciation of citric acid on anatase (TiO2)–water interface and its effect on Eu(III) sorption
- Separation of 134Cs and 137Cs from 125I solution for medical applications
- Optimization of 210Po estimation in environmental samples using an improved deposition unit
Artikel in diesem Heft
- Frontmatter
- Preface
- Separation Science in Nuclear Technology in India
- Studies on extraction of actinides by unsymmetrical diamylbutyl phosphonate
- Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds
- Novel polymer inclusion membranes containing T2EHDGA as carrier extractant for actinide ion uptake from acidic feeds
- Studies on the feasibility of using completely incinerable reagents for the single-cycle separation of americium(III) from simulated high-level liquid waste
- Phosphonates as alternative to tributyl phosphate for the separation of actinides from fission products
- Actinides draw down process for pyrochemical reprocessing of spent metal fuel
- Spectroscopic investigations on sorption of uranium onto suspended bentonite: effects of pH, ionic strength and complexing anions
- Speciation of citric acid on anatase (TiO2)–water interface and its effect on Eu(III) sorption
- Separation of 134Cs and 137Cs from 125I solution for medical applications
- Optimization of 210Po estimation in environmental samples using an improved deposition unit
