Hexafluorotantalate(V)-Selective Liquid Membrane Electrode Based on Brilliant Green
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Date
1990-06
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Addis Ababa Universty
Abstract
Brilliant Breen-hexafluorotantalate(V)extract in nitrobenzene
was used to prepare hexafluorotantalate(V) liquid membrane electrode
with a PVC support. The electrode body was made from the concentric
polypropylene tubes (16,5 cm long with internal diameter of the outer
and inner tubes, 8 mm and 4 mm, respectively)which were joined by a
corK. The liquid membrane electrode was connected with fluorideselective
electrode as internal reference and ground glass diaphragm
(Ag/AgCl) electrode as external reference electrode, to obtain the
complete cell assembly for the potential measurements. The concentrations
of sulphuric and hydrofluoric acids, for the optimum response
of the electrode to hexafluorotantalate(V) were found to be 1 ,0 M in
the test solutions. The response characteristics of the electrode
have been evaluated, and the electrode was found to respond to hexa- ~*6 -2 fluorotantalate(V) in the concentration range of 2.0 X 10 - 1.0 X 10
M tantalum(V) with a sub-Nernstian slope and detection limit of -58.5
ir.V/decade and 3,69 X 10 7 M tantalum(V), respectively.
The effects of forty diverse ions on the electrode response to
the hexafluarotantalate(V)abion have been studied to evaluate the
selectivity of the electrode. The newly developed liquid membrane
electrode has been applied successfully to the determination of
tantalum in tantalite-columbite ores by direct potentiometry, standard
addition and sample addition, and Gran’s plot potentiomstric techniques
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Keywords
Hexafluorotantalate(V)