Aqueous extracts of mango and orange peel as green inhibitors for carbon steel in hydrochloric acid solution

In this paper, aqueous extracts of mango and orange peels were shown to be good corrosion inhibitors for carbon steel in a 1 mol L- 1 HCl solution. The inhibition efficiency increased as the extract concentration increased over a concentration range of 200-600 mg L- 1, varying from 79 to 96% (mango) and 84 to 91% (orange) using Tafel plots and from 69 to 94% (mango) and 76 to 90% (orange) using electrochemical impedance. In the presence of 400 mg L- 1 of mango and orange peel extracts, the weight loss measurements showed an increase in the inhibition efficiency with immersion time, where the best results after 24 h of immersion were 97% and 95%, respectively. The adsorption of the extract components on the surface of the carbon steel follows the Langmuir adsorption isotherm. With the extraction procedure used in this work, it can be surmised that it is likely that the more polar heterosides in the extracts are responsible for the corrosion inhibition of carbon steel in an acid solution.