Voltammetric Studies of the Onset of Naaas Micellizations and Its Corrosion Inhibition for Carbon Steel

The critical micelle concentration (CMC) as well as the diffusion coefficients of the synthesized NaAAS surfactant were determined and discussed. The voltammetry of probed ferrocene solubilized in NaAAS surfactant was investigated using three different electrochemical techniques such as cyclic voltammetry, rotating disk voltammetry and chronocoulometry from aqueous buffer carbonate solutions of pH 10. The CMC of NaAAS was found to be 4.0×10-4 M using both CV and RDV techniques. Chronocoulometry showed negligible adsorption contribution to the electrode surface (1.0×10-15 M). The apparent diffusion coefficients were estimated from RDV measurements and the real micelles diffusion coefficients were obtained. Reequilibrium considerations of ferrocene probe kinetics at the electrode surface was treated according to two different modes of slowand fast-kinetics. The corrected diffusion coefficient values showed constancy at (4.69± 0.4)×10-7 cm2/sec in the concentration range from 20 to 200 mM NaAAS. The morphological features of NaAAS micelles showed globular selfassembled structure with no conversion to rod-like at higher NaAAS concentrations. The inhibition efficiency of carbon steel L52 was determined from 1 M HCl containing different NaAAS concentrations using weight loss measurements. The maximum inhibition efficiency was obtained at 4×10-4 M NaAAS corresponding to the predetermined CMC of the surfactant.