Natural Plants as Corrosion Inhibitors: Thermodynamic’s restrictions

Abstract

The flow of publication of articles on the use of natural plants extracts (NPEs) as corrosion inhibitors is very important in recent years; view the diversity of natural plants in each country.  A mapping of the large number of papers on NPEs is added using Scopus from 1993 to 2023 to show both most active authors in this topic. Corrosion inhibition is described by the adsorption of inhibitor’s molecules/ions on the metal surface to the metal to create a barrier against the arrival of aggressive ions as H⁺ or dissolved oxygen to cause degradation of the metal. The calculation of equilibrium constant, , and free enthalpy,  is possible and correct when one compound is used with known molecular weight, but when two or more compounds are used, the process is regarded as a synergistic intermolecular action.