Surface-enhanced Raman scattering spectroscopy studies on the inhibition mechanism of propargyl alcohol for iron corrosion in hydrochloric acid

In situ spectroscopic information on species adsorbed on the surface of iron in hydrochloric acid (HCl) solutions at 25 degrees C was obtained by surface-enhanced Raman scattering (SERS) spectroscopy of propargyl alcohol (HC=CCH2OH, or PA) using a SERS-active silver electrode covered with a thin layer of deposited iron. The SERS spectra of PA indicated the absence of a C=C bond and the presence of C=C, =C-H, and C-O bonds in the species derived from PA at the surface. Polarization curves of iron in 0.5 M HCl at 25 degrees C showed inhibition of the anodic process rather than of the cathodic one. Coverage of the iron surface with a film of the PA polymer and adsorption of allyl alcohol (CH2=CHCH2OH, or AA) on the surface were concluded from the results.