Inhibition of Microbial Corrosion by Green Inhibitors: An Overview

Corrosion is a spontaneous process that affects valuable metal products, is dangerous, and causes expensive damage to many industries. There are many kinds of corrosion; among them is microbial corrosion. The effect of Microbiologically Induced Corrosion (MIC) can be explained in three steps: development of biofilm, alterations of the environment of the metal surface, and metal degradation (or corrosion). Common bacteria responsible for inducing MIC are sulfate-reducing bacteria, iron-reducing bacteria, and acid-producing bacteria. Metals and alloys have been treated with corrosion inhibitors to prevent microbiological corrosion. Expensiveness, toxicity, and in certain instances, ineffectiveness of these inorganic inhibitors have shifted the attention towards the organic green inhibitors. These green inhibitors used against corrosion are derived from plant extracts and organic substances. In addition to being ecologically acceptable and environmentally friendly, plant extracts are readily available, inexpensive, and renewable. This review paper explains microbial corrosion in metals and the mechanisms of MIC. In addition, this paper also reviews metal corrosion inhibition, green inhibitors, their types, and the impact of molecular structures on corrosion inhibition.