Synergistic effects in solvent-extraction systems based on alkylsalicylic acids. I. Extraction of trivalent rare-earth metals in the presence of aliphatic amides
- Mintek, Randburg (South Africa)
Aliphatic carboxylic acid amides were found to cause synergistic shifts in the pH{sub 50} values for the extraction of the trivalent rare-earth metals from chloride media by solutions of alkylsalicylic acids in xylene. For the different types of amide examined, the synergistic shifts for the extraction of neodymium by 3,5-diisopropylsalicylic acid (DIPSA) generally decrease in the order: R.CO.NR{sub 2}` > R.CO.NHR` > R.CO.NH{sub 2}, where R and R` are alkyl groups. With the N,N-dialkyl amides (R.CO.NR{sub 2}`) and the N-alkyl amides (R.CO.NHR`), the extent of the synergistic effect decreases with increasing chain-branching in either of the alkyl groups R and R`. For additions to 0.25 M alkylsalicylic acid, the synergistic effect increases with concentrations of up to 0.1 M amide, and decreases with higher concentrations. The extent of the synergistic shift produced by a given amide, as well as the separation in pH{sub 50} values from lanthanum to lutetium, increases with increasing steric bulk of the alkylsalicylic acid used. The separations between adjacent lanthanides are too small to be of any practical interest, however. Measurement of the solubility of salicylic acids (HA) in xylene containing various amounts of N,N-dialkyl amide (L) indicate that essentially complete formation of the HA.L adduct takes place. Treatment of metal-distribution data by slope analysis, and measurement of the solubility of the neodymium-DIPSA complex in xylene in the presence of amide suggest that the mixed-ligand complex has the stoichiometry NdA{sub 3}L{sub 2}. 18 refs., 6 figs., 3 refs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 70362
- Journal Information:
- Solvent Extraction and Ion Exchange, Journal Name: Solvent Extraction and Ion Exchange Journal Issue: 4 Vol. 13; ISSN 0736-6299; ISSN SEIEDB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Solvent extraction of uranium(VI) and thorium(IV) from nitrate media by carboxylic acid amides
Application of N,N-dialkyl aliphatic amides in the separation of some actinides