Browsing by Author "Megersa Negussie"

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    Hexafluorotantalate(V)-Selective Liquid Membrane Electrode Based on Brilliant Green
    (Addis Ababa Universty, 1990-06) Megersa Negussie; Chandravanshi B.S. (PhD)
    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