Abstract
The electrochemical behavior of 1,4-napthoquinone (1,4-NAQ) and 2-methyl-1,4-naphthoquinone (2-Me-1,4-NAQ) was investigated in bis-(2-ethylhexyl) sulfosuccinate (EHSS) anionic surfactant and its microemulsion system as well as in aqueous medium using cyclic voltammetry, rotating disk voltammetry and chronocoulometry techniques. The voltammograms of both compounds in all media exhibit a single redox couple and the ratios of Ipa/Ipc is slightly less than unity in all media. The Ip – v1/2 plots gave linear correlations slightly deviated from the origin which denoting that the electrode reaction is mainly controlled by diffusion with slight adsorption contribution. For 1,4-NAQ and 2-methyl-1,4-NAQ in all media, the peak separation (Δ Ep), is not close to the theoretical value of completely reversible 2-electron transfer process (30 mV) which denotes that an ECE reaction nature and the reduction process of both compounds is quasi-reversible. This behavior is further confirmed by the cathodic shift of the rotating disk voltammograms as the angular velocity increases and the data of this technique were found in a good agreement with that obtained from cyclic voltammetry. The diffusion coefficient values of both compounds were calculated and the electrode reaction mechanism was suggested.