Potential use of natural dyes extracted from Melastoma malabathricum L. seeds as corrosion inhibitors on low carbon steel: A review.

Anthocyanins are compounds that can be obtained naturally in many plants. Interestingly, cyanidin and glycosides, which are one of the main groups of natural anthocyanins, have aromatic rings so that anthocyanins tend to bond to metal surfaces through heteroatomic interactions or π-π interactions. These properties lead to potential applications of anthocyanins as corrosion inhibitors. The inhibition efficiency of organic compounds is closely related to their adsorption properties. It is known that adsorption mainly depends on the presence of heteroatoms and π electrons which causes greater adsorption of the inhibitor molecules on the metal surface. Melastoma malabathricum L. plant has been identified to contain delphinidin hexoside, cyanidin delphinidin dihexoside, cyanidin hexoside, and cyanidin dihexoside. This shows that Melastoma malabathricum L. is rich in anthocyanins. Because of that, it is expected that this plant has a high potential to be used as an organic inhibitor. In this paper, several extraction methods for natural dyes have been reviewed including Melastoma Malabathricum L. seeds. In general, the higher the inhibitor concentration, the higher the effect of the corrosion inhibition on low carbon steel in an acidic environment up to a critical concentration. [ABSTRACT FROM AUTHOR]