Vibrational spectral studies of solutions at elevated temperatures and pressures. VII. Raman spectra and dissociation of nitric acid

1985 ◽  
Vol 63 (12) ◽  
pp. 3521-3525 ◽  
Author(s):  
C. I. Ratcliffe ◽  
D. E. Irish
Keyword(s):  
Hydrogen Bonding ◽  
Nitric Acid ◽  
Raman Spectra ◽  
Exploratory Study ◽  
Elevated Temperatures ◽  
Spectral Studies ◽  
Acid Solutions ◽  
Concentration Increase ◽  
Degree Of Dissociation ◽  
Nitric Acid Solutions

An exploratory study of the Raman spectra of nitric acid solutions up to 250 °C has been undertaken. The decrease in the frequencies of the νN—(OH) and δNO2 bands of HNO3 as temperature and concentration increase have been interpreted in terms of the reduced strength of hydrogen bonding. Approximate values of the degree of dissociation α have been determined and show that nitric acid is a very much weaker acid at high temperatures.

Metal extraction by N,N′-dialkyl-N,N′-diaryl-dipicolinamides from nitric acid solutions

2007 ◽  
Vol 95 (4) ◽  
Author(s):  
V. A. Babain ◽  
M. Yu. Alyapyshev ◽  
R. N. Kiseleva
Keyword(s):  
Nitric Acid ◽  
Acid Concentration ◽  
Alkyl Radical ◽  
Dipicolinic Acid ◽  
Nitric Acid Concentration ◽  
Metal Extraction ◽  
Acid Solutions ◽  
Concentration Increase ◽  
Nitric Acid Solutions ◽  
Radical Length

A study of americium, uranium and europium extraction by various dialkyl-diarylamides of 2,6-pyridine-dicarboxylic (dipicolinic) acid has shown that maximum extractability is achieved by using polar fluorine-substituted diluents. Generally, the diamide extractability is found to increase with the alkyl radical length. We have demonstrated the possibility to separate Am and Eu in solutions with a nitric acid concentration of 0.5–2 mol/l. The extractability of these diamides with respect to the three metals rises with the acid concentration increase to 6 mol/l.

scholarly journals Neptunium extraction by N,N-dialkylamides

2020 ◽  
Vol 108 (9) ◽  
pp. 707-716
Author(s):  
Jarrod M. Gogolski ◽  
Peter R. Zalupski ◽  
Travis S. Grimes ◽  
Mark P. Jensen
Keyword(s):  
Nitric Acid ◽  
Solvent Extraction ◽  
Radioactive Waste ◽  
Partial Oxidation ◽  
Acid Solutions ◽  
Nitric Acid Solutions ◽  
Organic Solutions

AbstractSeparation of neptunium by solvent extraction has been based on tributylphosphate (TBP) for decades, but TBP is not fully incinerable, which adds to the burden of long-lived radioactive waste. Alternatives to TBP for uranium and plutonium extraction, such as the N,N-diakylamides, previously have been explored in the hopes of transitioning to an extractant that is incinerable. Four N,N-diakylamides, N,N-dihexylhexanamide (DHHA), N,N-dihexyloctanamide (DHOA), N,N-di(2-ethylhexyl)butanamide (DEHBA), and N,N-di(2-ethylhexyl)-iso-butanamide (DEHiBA) were considered in this work for their potential to extract millimolar concentrations of Np(IV), Np(V), and Np(VI) from nitric acid solutions into organic solutions containing 1 M extractant in Exxsol D60. Under these conditions the branching of the alkyl substituents affects the extractability of Np(VI) and Np(IV), causing three of the dialkylamides, DHHA, DHOA and DEHBA, to extract neptunium in the expected order Np(VI) > Np(IV) > > Np(V). In contrast, branched DEHiBA is so poor an extractant for Np(IV) that the extraction order becomes Np(VI) > > Np(V) > Np(IV) between 0.1 and 5.6 M HNO3 due to partial oxidation of the Np(V) in nitric acid.

Extraction of tetra- and hexavalent actinide ions from nitric acid solutions using some diglycolamide functionalized calix[4]arenes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rajesh B. Gujar ◽  
Parveen K. Verma ◽  
Prasanta K. Mohapatra ◽  
Mudassir Iqbal ◽  
Jurriaan Huskens ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Solvent Extraction ◽  
Extraction Efficiency ◽  
Minor Actinide ◽  
Acid Solutions ◽  
Extraction Mechanism ◽  
Nitrate Ion ◽  
Nitric Acid Solutions ◽  
Actinide Ions ◽  
Acid Extractant

Abstract Neptunium is one of the most important minor actinide elements with some of its isotopes having very long half-lives, therefore necessitating its separation from acidic radioactive wastes. Solvent extraction of Np4+ and NpO2 2+ was studied using three multiple diglycolamide (DGA) extractants with n-propyl, n-octyl and 3-pentyl substituents termed as L I , L II and L III , respectively, in a mixed diluent of 5% isodecanol and 95% n-dodecane. For comparison purpose, the extraction of Pu4+ and UO2 2+ was carried out under identical conditions. The extraction efficiency of the ligands for the tetravalent ions followed the trend: L II  > L I  > L III , which changed to L III  > L II  > L I for the hexavalent ions. While the extraction of the tetravalent ions was reasonably good (ca. 90–98%) with an extremely low (5.0 × 10−5 M) ligand concentration, poor extraction (ca. 5–16%) of the hexavalent ions was seen even with a 20 times higher concentration of the ligand. In general, Pu4+ was better extracted than Np4+, while NpO2 2+ was marginally better extracted then UO2 2+. A ‘solvation’ type extraction mechanism was proposed based on the extraction profiles obtained as a function of the concentrations of the feed nitric acid, extractant as well as nitrate ion. The extracted species were found out to be M(NO3)4·mL and MO2(NO3)2·nL (M = Np or Pu, 1 < m < 2, n ≃ 1).

Separation of Americium and Curium in Nitric Acid Solutions via Oxidation of Am(III) by Bismuthate and Perxenate Ions

2020 ◽  
Vol 62 (5) ◽  
pp. 581-586
Author(s):  
Yu. M. Kulyako ◽  
D. A. Malikov ◽  
T. I. Trofimov ◽  
S. A. Perevalov ◽  
K. S. Pilyushenko ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Acid Solutions ◽  
Nitric Acid Solutions
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