Corrosion of copper in hydrochloric acid solutions

• Ya.G. Avdeev, A.K. Mitrushonkova and T.E. Andreeva

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: Some regularities of metallic copper corrosion in HCl solutions, including media containing Cu(II) chloride and Fe(III) chloride, were examined. Analysis of E–pH and E–pCl^– diagrams of the Cu–H₂O–Cl^– system provided important information about the possible chemical reactions occurring during the corrosion of copper in these media and the products formed. Based on weight loss data for metal samples in the corrosive media, the corrosion rates of M1 copper in HCl solutions (20±2°C) were determined at various exposure times and hydrogen chloride concentrations in the corrosive medium. It was found that the corrosion of copper in 2 M HCl accelerates with time (for up to 6 days). The maximum observed metal corrosion rate was 5.2 g/(m²∙h). Prolonged contact of copper with 2 M HCl (12 days) can result in significant mass loss of the metal (1270 g/m²) due to corrosion. The accumulation of Cu(II) chloride in HCl solutions during corrosion of metallic copper is responsible for the acceleration of this process, since Cu(II) cations, along with dissolved air oxygen, participate in the corrosion process as an oxidizing agent. The presence of Fe(III) chloride in HCl solutions accelerates the corrosion of copper, especially during short-term contact (1 h) of the metal with the corrosive medium. This regularity should be taken into account for industrial conditions where process solutions of HCl contaminated with FeCl₃ come into contact with copper equipment.

Keywords: acid corrosion, copper, hydrochloric acid, copper(II) chloride, iron(III) chloride

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1469-1480
doi: 10.17675/2305-6894-2025-14-3-23

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