Plant Extracts as Green Corrosion Inhibitor for Ferrous Metal Alloys: A Review

Abstract Significant investigative research has been focusing on the development of corrosion inhibitors for ferrous metal alloys. One of the most extensive investigations is the development of green corrosion inhibitors (GCIs). The GCIs from plant extract, which are the most widely investigated due to inexpensive, renewable, biodegradable and foremost aspect, are safe towards both the environment and human being. The performance of GCIs is evaluated by gravimetric analysis, electrochemical tests as well as theory and computational-based studies. A compilation of the inhibition performance calculated from these methods in various conditions is well reported. Plant extracts proved to be a good corrosion inhibitor where the result of inhibition efficiency is over 80%. This high efficiency is related to the high concentration of active constituent known as phytochemicals. In addition, the performance of GCIs also can be elucidated by the determination of inhibitor type and inhibition mechanism. This review broadly summarised the preparation, performance and inhibition mechanism determination of plant extracts as GCIs for ferrous metal alloys. This review concluded that plant extracts as GCIs were of high potential for corrosion protection of ferrous metal alloy; thus, further improvement action are still necessary to achieve the highest inhibition efficiency of approximately 100%.