Synergistic effect of salts on the corrosion inhibitive action of plant extract: a review

Corrosion inhibition and control are of great significance in metal industries due to the economic benefits. In recent years, the utilization of plant extract as an alternative to the chemical counterparts has advocated the concept of a green approach that is eco-friendly nature and efficient as corrosion control agents. Literature review reveals that the inhibition efficiency of a plant extract could be improved by the addition of cationic or anionic salts along with it. Majorly, the effect of halogen and zinc ion based salts has been reported to produce an effective synergistic corrosion control in the presence of plant extracts. The present review is a collection of published work on the synergistic effect of different types of salt on the corrosion inhibitive action of plant extract. The comprehensive data directs that the effective use of ionic salts along with plant extracts can maximize the inhibition efficiency and minimize the requirement of the plant extract required to produce an effective corrosion inhibition. Further, the corrosion inhibition mechanism of the mixture of plant extract and salt directs attention that these ionic compounds improve the corrosion inhibition efficiency by assisting the formation of the plant extract-based protective layer on metallic surface.