Pre-concentration of Ta(V) by solvent extraction before determination of trace amounts of Ta in Nb and Nb compounds

Analytical Methods Pub Date: 2016-06-01 DOI: 10.1039/C6AY01231K

Abstract

The paper presents the results of a study on the efficiency of the separation of Ta(V) and Nb(V) from fluoride solutions by solvent extraction with methyl isobutyl ketone with a view to applying the extraction process to the purification of Nb from Ta and for the pre-concentration of Ta prior to its determination in Nb and its compounds over a wide range of initial concentrations. With strict control of the hydrofluoric acid concentration and the re-extraction of Ta into an aqueous phase using an ammonium oxalate solution, the mean recovery factors [R with combining macron][%] for Ta were 94–108% in the initial weight ratio mNb?:?mTa = (ρNb/Ta) range 10–1?000?000 with only a small scatter about the mean value (RSD ≤ 6%), with the exception of (ρNb/Ta) = 1?000?000. The effect of the composition of the re-extraction solution on the excitation conditions of Ta in ICP-OES (ICP-MS) plasma was negligible and small amounts of Nb and other contaminants co-extracted with Ta did not affect its determination.

Graphical abstract: Pre-concentration of Ta(V) by solvent extraction before determination of trace amounts of Ta in Nb and Nb compounds
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