Inhibitive properties, adsorption and surface study of butyn-1-ol and pentyn-1-ol alcohols as corrosion inhibitors for iron in HCl

The inhibiting effect of several acetylenic alcohols, namely 2-butyn-1-ol, 3-butyn-1-ol, 3-pentyn-1-ol and 4-pentyn-1-ol has been investigated on the corrosion of iron in 1 M HCl. The Tafel extrapolation method, linear polarization resistance and electrochemical impedance spectroscopy illustrate their inhibiting effect. Results show that all of these compounds suppress both the anodic and cathodic process, i.e., they are mixed-type inhibitors. The changes of charge transfer resistance are indicative of adsorption and inhibition. This effect increases with time over a 16 h period. Equivalent circuits are suggested as a model for the impedance spectra. The inhibition efficiency of the alkynol depends on the length of the carbon chain and the position of the triple bond. Some structural and electronic effects are discussed in relation to the inhibiting efficiencies. Determination of the chemical speciation, as well as elemental ratio were obtained via XPS and morphological changes were monitored by SEM.