Corrosion Mitigation with Nature-Inspired Green Inhibitors: A Review of Steel Protection in Acidic Media

This review highlights recent advancements in the use of green corrosion inhibitors for steel in acidic environments, such as those found in industrial processes like acid pickling and oil well acidizing. Traditional chemical inhibitors, though effective, are increasingly restricted due to their environmental toxicity and health hazards. Green inhibitors—sourced from plants, biopolymers, amino acids, and agricultural waste—have gained attention for being biodegradable, non-toxic, cost-effective, and rich in functional groups (e.g., N, O, S atoms, and π-electrons) that enable strong adsorption onto steel surfaces. This adsorption creates a protective layer, effectively reducing corrosion. Inhibition performance, often between 80–97%, is evaluated through methods such as weight loss analysis, gasometric and thermometric techniques, and electrochemical testing (EIS and Potentiodynamic Polarization). Surface characterization tools (SEM, AFM, DFT) confirm the formation of protective films. Most green inhibitors act as mixed-type inhibitors, impacting both anodic and cathodic reactions, with adsorption behavior typically following Langmuir or Temkin isotherms. The review also identifies ongoing challenges—particularly in achieving consistent performance at elevated temperatures, developing standardized testing protocols, and utilizing computational modeling for inhibitor design. Despite these limitations, green inhibitors represent a sustainable and effective solution for corrosion control in industries like oil and gas, marine, construction, and automotive, supporting broader goals of environmental protection and resource efficiency.