The electrochemical studies of Eosin Y on glassy carbon electrode were carried out in the different pH conditions by cyclic voltammetey, Chronocoulometry, Controlled potential coulometry and reaction mechanism. The effect of pH on the peak current and peak potential was studied at different pH media. Maximum peak current was observed only at pH 4.0. It was chosen as the best pH for studying the electroanalytical behaviour of eosin Y. Cyclic voltammograms were recorded in the potential range from -1000 V to 1000 mV. The voltammogram shows one oxidation peak at 814.4 mV with peak currents 3.46 A and reduction peak with higher current of 6.4 A in the backward scan at -704.5mV. A well-developed voltammetric peak probably related to the cathodic reduction of carbonyl group was obtained in pH 4.0 acetate buffer at -704 mV. An irreversibility nature of the reduction process was confirmed by cyclic voltammetric technique. From the slope value observed from the plot of Q vs. t 1/2 , the diffusion coefficient was calculated. The number of electrons involved in the overall process was calculated by substituting the diffusion coefficient 'D' calculated from chronocoulometry. The number of electrons transferred was 2 for reduction per molecule and 1 for oxidation in all the selected pH conditions was measured through controlled potential coulomogram. The oxidation involved irreversible one electron transfer around 800 mV, a potential where the oxidation of phenolic OH group took place. Hence the oxidation peak is due to the oxidation of phenolic OH group to the corresponding radical.

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