Hexafluorotantalate(V) – Selective Coated-Graphite Electrode
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Date
1993-06
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Addis Ababa Universty
Abstract
The Hexafluorotantalate(V)-selective coated-graphite
electrode was prepared by using a Brilliant Greenhexafluorotantalate(
V) extract in 1-chloronaphthalene with a
PVC matrix. The electrode body was prepared by fixing a
graphite rod to one end of a glass tube housing a copper coil,
so that the electrode is in contact with it. The potential
measurement with the coated-graphite electrode was made against
a sintered ground glass diaphragm (Ag/AgCl) external reference
electrode. The concentrations of sulphuric and hydrofluoric
acids, for optimum response of the electrode to
hexafluorotantalate (V) were found to be 1 M in the test
solutions. The response characteristics of the electrode have
been evaluated, and the electrode was found to respond to
hexafluorotantalate(V) in the concentration range of 5.0 x 10~
- 5.0 X 10-3 M tantalum (V) with a Nernstian slope ( 58±1 mV per
decade) and the detection limit of 8.0 x 10-7 M.
The effects of forty diverse ions on the electrode
response to the hexafluorotantalate (V) have been studied to
evaluate the selectivity of the electrode, and the electrode
was found to be highly selective to hexafluorotantalate(V). The
newly developed coated-graphite electrode has been applied to
the determination of tantalum in tantalite-columbite ores and
several artificial matrices by direct, standard addition,
sample addition and Gran's plot potentiometric techniques. The
experimental results are found to be in good agreement with the
actual or certified values.
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Keywords
Hexafluorotantalate( V)