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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/14766
Title: Development of Detergent Sensitive Electrodes and Studies of the Charge Transfer Reaction at These Electrodes
???metadata.dc.contributor.*???: Dr. B. Hundhammer
Alemayehu, Beniam
Issue Date: Jun-1981
Publisher: Addis Ababa University
Abstract: In tetraphenylboratel-crystal violet tetraphenylborate and crystal .violet-dodecyl sulphate were used as base ele-ctrolytes for the organic phase, while 0.01H LiF and 0.101 NaF were used as base electrolytes for the aqueous phase. In these systems, the transfer of dodecyl sulphate ion across the interface of two immiscible electrolyte sqlu- tions has been studied employing cyclic voltammetry. The results of these studies show a rapid and reversible tran-sfer of dodecyl sulphate ion both from the nitrobenzene Phase to the aqueous phase and also for the transfer in the opposite direction upon the reversal of the polarization. This behaviour requires that the potential forming step is established immediately and that there is a 60 my potential change per decade concentration change in the potentiometric measurment. The over-}Ternstian behaviour that was exhibited by the carbon paste electrode does not appear to be accounted for by the cyclic volta-mmetric studies. The effect of the carbon powder on the electrode process needs to be investigated as this subst-ance has not been included in the voltammetric studies. The diffusion coefficient of dodecyl sulphate in aqueous solution has been evaluated from the voltammetric 'measurements. . The values, DDS-- were.found to be.fllI 0007 x 10-5 cm2 -1$-1 and This, value conform well with a value, as 71- • -6 2 -1 D 4DS 5 (W) 9 x 10 cm S calculated from conductance measurment at infinite dilution. The quantity 1 which is analogous to the reversible polarographic half--wave potential, was obtained for the transfer .of dodecyl sulphate ion across the water•nitrobenzene interface. The value estimated from the vol-tammetric measurment i.e00,221 V is comparable to the value obtained using the extraction data which was 0.205 V when TBA4 was taken as a reference. The free energy of transfer nB of the DS' ion from water to nitrobenzene, ING - trops was calculated to be 19068 kJ/mole. The type of base electrolyte employed in the volta-mmetric studies have made it possible to evaluate the Wipo T formal potential difference of F- ion, j rThe nB ° nB value was estimated to be 0.392 V and the LI Gtr, r- was i calculated to 37,83 kJ/mole. It is evident from the results given above, that reproducable and reasonable values have been obtained even without IR-drop compensation and using a relatively simple electronic cir.Juit. Below the critical micelle concentration, the transfer of dodecyl sulphate across the hitrobenzene/water interface has been reported to be reversible. However above this concentration (10-3M) the voltammogram obtained appears to show an unexpected pattern ae shown in Figure 3O.
Description: A Thesis Presented To the School Of Graduate Studies Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Chemistry
URI: http://hdl.handle.net/123456789/14766
Appears in Collections:Thesis - Chemistry

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