Chandravanshi B.S. (PhD)Amare Bizuayehu2018-06-162023-11-092018-06-162023-11-091996-06http://etd.aau.edu.et/handle/12345678/1041An attempt was made to develop hexafluorotantalate(V)-selective coated graphite electrodes based on Malachite Green, Crystal Violet, and Ethyl Violet using fchloronaphthalene, tri-n-bUI)'1 phosphate, and dimethylphthalate as plasticizers. The electrode prepared by coating Malachite Green-hexaflllorotantalate(V) extract in fchloronaphthalene \Vith a PVC matrix on a graphite rod \Vas found to give a Nernstian response and hence was studied in detail. Potential measurements with the coated graphite electrode were made against a plastic sleeve HF-resistant Ag/AgCI external reference electrode. Optimum response of the electrode was observed in test solutions made 1 mollL in both sulphuric and hydrofluoric acids. The response characteristics of the electrode were evaluated. The linear range, slope, and detection limit were found to be f.O x f 0.5 - 1.0 X 10.2 mollL tantalum(V), 58.0 ± 1.5 mV/decade, and 3.98 x 1rJ mollL tantalllm(V), respectively. The precision of the method developed \Vith the electrode \Vas estimated to be 2% and the electrode functioned properly for three months. The effects of diverse ions on the electrode response to hexafluorotantalate(V) were studied, and the potentiometric selectivity coefficients lVere evaluated. The electrode was found to be highly selective to hexafluorotantalate(V). It was found that the response of the electrode to hexafluorotantalate is free from inteiference of niobium which commonly occurs with tantalum. The analytical application of the electrode to the detennination of tantailim in synthetic matrices and real ore samples was also studied. The results obtained using four potentiometric techniques are in good agreement \Vith the actllal or certified values.enHexafluorotantalate(V)-selective coated graphite electrodesThesis