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 (C
MC). High corrosion Inhibition is observed when medium pH value is low
er than organic compound pKa. When the concentration is close to the C
MC, the organic compounds operate on the anodic and cathodic process a
nd a bimolecular layer is formed. The inhibiting effect is reduced wit
h an increase of medium pH value. This is explained by the complexing
of NaBr with the zwitterionic form of organic compounds.