Effect of N-Alkylbetaines on the Corrosion of Iron in 1 M HCl Solution

Using potentiodynamic and transient electrochemical methods and weight loss shows that N-alkylbetaines are good inhibitors of iron corrosion in HCl at concentrations around the critical micelle concentration (CMC). High corrosion inhibition is observed when medium pH value is lower than organic compound pKa. When the concentration is close to the CMC, the organic compounds operate on the anodic and cathodic process and a bimolecular layer is formed. The inhibiting effect is reduced with an increase of medium pH value. This is explained by the complexing of NaBr with the zwitterionic form of organic compounds.