Extraction of Metal Nitrates by TBP·HNO3
- 1 August 1963
- journal article
- research article
- Published by Taylor & Francis in Nuclear Science and Engineering
- Vol. 16 (4), 421-427
- https://doi.org/10.13182/nse63-a26554
Abstract
The extraction by TBP of nitrato complexes of metals occurs mainly by the formation of nonconducting complexes in which the oxygen of the PO group is covalently bound to the metal, e.g., P==0 → M. In other TBP complexes, this O atom is bonded to hydrogen, e.g., to a hydrogen atom of water, of an undissociated acid, or of the hydronium ion. Three features in the extraction of metal nitrates at trace concentration from nitric acid concentrations >7M which await interpretation are the second increase in the distribution coefficient, DM; the decrease in the magnitude of this second increase as the fraction of inert diluent increases; and the change in the temperature coefficient of DM from negative to positive. Extraction (i) by bonding of the phosphoryl oxygen to an aquo group (of the aquonitrato metal complex), or (ii) by nitrato acids, do not explain these features. Measurements of the conductivity and viscosity of 100% TBP-HNO3-H2O phases are consistent with the existence of three steps as the ratio HNO3/TBP increases. In the first step, ions, postulated as (TBP·H2O·H)3O+ and (TBP·H)2(H2O·H)O+, are formed. In the second step, the molar conductivity decreases as the predominant species becomes TBP·HNO3. In the third step the molar conductivity and the water content increase by the formation of ions such as (TBP·H)(H2O·H)(HNO3·H)O+, in which a nitric acid molecule is bonded to the hydronium ion: the second increase in DM for certain metals is explained by there being similar bonding, through the oxygen of a nitrato group of the metal complex, in place of the HNO3 in this complex ion when HNO3/TBP is >1. The positive temperature coefficient shown by this form of extraction of metal nitrates is also shown in this region by the extraction of nitric acid, the conductivity, and the water content.Keywords
This publication has 14 references indexed in Scilit:
- The solvent extraction of plutonium and americium by tri-n-octylphosphine oxideJournal of Inorganic and Nuclear Chemistry, 1961
- THE PRIMARY SOLVATION OF THE PROTON IN THE SOLVENT EXTRACTION OF STRONG ACIDS1The Journal of Physical Chemistry, 1961
- 33. The solvent-extraction of beryllium from aqueous solutions of mineral acids by alkyl esters of phosphoric acidJournal of the Chemical Society, 1961
- 332. The nitrous acid–tributyl phosphate complexJournal of the Chemical Society, 1961
- Solute-solvent interaction in the system hydrochloric acid-water-tri-n-butyl phosphateJournal of Inorganic and Nuclear Chemistry, 1960
- The extraction of mineral acids by tri-n-butyl phosphate (TBP)Journal of Inorganic and Nuclear Chemistry, 1960
- SOLVENT EXTRACTION OF MINERAL ACIDS: PART III. SOLUTE–SOLVENT INTERACTION IN THE SYSTEM HYDROBROMIC ACID – WATER – TRI-n-BUTYL PHOSPHATECanadian Journal of Chemistry, 1960
- Tri-n-butyl phosphate as an extracting agent for inorganic nitrates—VI Further results for the rare earth nitratesJournal of Inorganic and Nuclear Chemistry, 1959
- The extraction of nitrates by tri-n-butyl phosphate (TBP). Part 3.—Extraction at trace concentrationsTransactions of the Faraday Society, 1958
- Nonmonotonic ordering of lanthanides in tributyl phosphate-nitric acid extraction systemsJournal of Inorganic and Nuclear Chemistry, 1957