Some aspects of the mechanism of steel protection in mineral acid solutions by propargyl alcohol and propargyl chloride

• Ya.G. Avdeev¹ and K.L. Anfilov²

¹ A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation
² Bauman Moscow State Technical University (Kaluga Branch), Bazhenov str. 2, 248000 Kaluga, Russian Federation

Abstract: The specific features of iron corrosion in HCl, H₂SO₄ and H₃PO₄ solutions with addition of propargyl alcohol (PA), propargyl chloride (PC) and products of their reduction on iron in the corrosive system, namely, allyl alcohol (AA) and allyl chloride (AC), were studied by voltammetry. PA and PC have the strongest inhibitory effect on the cathodic and anodic reactions of iron in HCl solutions, while PC has such an effect in H₂SO₄ solutions as well, among the unsaturated compounds (UC) studied since these compounds form protective films of organic polymers on the metal surface. AA and AC slow down the electrode reactions of iron in HCl, H₂SO₄ and H₃PO₄ solutions much more weakly. It has been shown that the presence of adsorbed atomic hydrogen on its surface often enhances the inhibitory effect of the UCs studied on the electrode reactions. The AA and AC compounds studied are cathodically reduced on iron under diffusion control. Analysis of experimental data shows that the conversion of PA and PC to AA and AC on the metal surface in the course of inhibition of the corrosion of iron or steels in acid solutions is an undesirable process. The compounds that are formed slow down the electrode reactions and the corrosion of metals more poorly than the original inhibitors.

Keywords: acid corrosion, corrosion inhibitors, propargyl alcohol, allyl alcohol, propargyl chloride, allyl chloride, unsaturated organic compounds, acetylenic alcohols, mild steel

Int. J. Corros. Scale Inhib., 2022, 11, no. 4, 1604-1627
doi: 10.17675/2305-6894-2022-11-4-12

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