Inhibitory action of aqueous coffee ground extracts on the corrosion of carbon steel in HCl solution

The effects of aqueous extracts of spent coffee grounds on the corrosion of carbon steel in a 1 mol L−1 HCl were examined. Two methods of extraction were studied: decoction and infusion. The inhibition efficiency of C-steel in 1 mol L−1 HCl increased as the extract concentration and temperature increased. The coffee extracts acted as a mixed-type inhibitor with predominant cathodic effectiveness. In this study, the adsorption process of components of spent coffee grounds extracts obeyed the Langmuir adsorption isotherm. The chlorogenic acids isolated do not seem to explain the corrosion inhibition observed during the use of the coffee extracts.

► Extracts of coffee grounds can act as an effective corrosion inhibitor for C-steel in HCl solution.
► All electrochemical results showed that the examined extracts acted as mixed-type inhibitor.
► The inhibition efficiency increased with the extract concentration and temperature.
► The apparent activation energy (Ea) of C-steel dissolution decreased in the presence of the extract.