The electrochemical behaviour of halogens redox couples is studied on carbon graphite electrode by voltammetry under different conditions (pH, Concentration, Cation and Temperature). It is found that there is a large difference in current density behaviour between the different halogen electrolytes at a concentration of 2M (I- 400mA/cm² and Br^- 250mA/cm² oxidation peak at 1.5V) as shown in Figure 1. Besides this, it is found that changing the cation salt  (e.g. NaBr and ZnBr₂) affected the current density to a great extent, the effect is observed more clear when the concentration of the electrolytes are changed from 3M to 8M. This effect may be related to pH changes caused by the identity of the cation (Na and Zn). In general, the pH is found to affect oxidation of halogens substantially at pH lower than 5. In line with these results, the diffusion coefficient increases when acid is added to the electrolytes. As expected, the current density increased when temperature is raised and the activation energy have a value of 45kj/mol for the Br- oxidation at carbon graphite. Finally, It is found with UV-Vis experiments that halogen oxidation at carbon graphite shifts to a lower peak wavelength when cation is change and differs from pure halogen spectra. 

Key words: Halogens, Voltammetry, graphite