DETERMINATION OF THE DIFFUSION-COEFFICIENT FOR SDS MICELLE WITH DIFFERENT SHAPE AND THE EFFECTS OF ETHANOL BY CYCLIC VOLTAMMETRY WITHOUT PROBES

Micelle diffusion coefficient of SDS with different micelle shape in a queous and water-ethanol solutions are determined by cyclic voltammetr y without any probe. The diffusion coefficient decreases with as incre asing SDS concentration. The first critical micellar concentration is 8.0x10(-3) mol . l(-1) corresponding to the transformation from premic elle to spherical micelle. The second critical micellar concentration is 5.60x10(-2) mol . l(-1) and corresponding to transformation from sp herical micelle to rod-like micelle. The less the weight ratio of SDS to ethanol is, the larger the diffusion coefficient is. The influence of added water to the micelle solution is almost the same for SDS-etha nol-H2O system with different micelle shape. Mechanism of electrochemi cal reaction for SDS at platinum electrode is discussed as well.