Solvent extraction by dialkyl-substituted diphosphonic acids in a depolymerizing diluent. Part I : alkaline earth cations.
In this work, the extraction of Ca{sup 2+}, Sr{sup 2+} and Ba{sup 2+} by P,P'-di(2-ethylhexyl) methylene- (H{sub 2}DEH[MDP]), ethylene- (H{sub 2}DEH[EDP]), and butylene- (H{sub 2}DEH[BuDP]) diphosphonic acids, has been investigated in the monomerizing diluent 1-decanol. In all cases, the slope of the acid dependencies at low aqueous acidities equals -2, indicating that two protons are displaced from the extractant molecules, regardless of the type of complexes formed in the organic phase. Extraction of metal nitrates through a solvation mechanism, however, has also been identified. The extractant dependency data exhibit variable slopes, consistent with the simultaneous formation of complexes having 1:1 (MA) and 1:2 (MA{center_dot}H{sub 2}A or M(HA){sub 2}) metal to ligand stoichiometry (where A denotes the anion of the extractants). The latter species becomes predominant at higher extractant concentrations. Based on the selectivity sequences observed for the alkaline earth cations with the di(2-ethylhexyl) diphosphonic acids, probable structures have been assigned to the metal-extractant complexes. Comparison of the extraction data in 1-decanol with those obtained previously in o-xylene shows that 1-decanol strongly suppresses metal extraction by the di(2-ethylhexyl) diphosphonic acids. This is consistent with strong hydrogen-bonding of the monomeric extractant molecules with the diluent.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 943055
- Report Number(s):
- ANL/CHM/JA-37119; SEIEDB; TRN: US1000533
- Journal Information:
- Solvent Extr. Ion Exch., Vol. 19, Issue 2 ; Mar. 2001; ISSN 0736-6299
- Country of Publication:
- United States
- Language:
- ENGLISH
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