Green corrosion inhibitors based on biomacromolecules and macrocycles: A review

Biodegradable biological molecules, including macrocycles and naturally occurring biopolymers, are well-known for their various biological activities and pharmaceutical applications. These biomolecules are reported for their environmentally benign nature and considerable corrosion inhibition efficiency in aggressive aqueous media. The sizeable molecular framework with plenty of available metal-inhibitor interaction sites facilitates effective surface adsorption. Further, to achieve improvement in corrosion inhibition performance, different chemical functionalization methods have been explored. Consequently, the application of macrocycles and large biomolecules is an attractive topic of research in the area of green corrosion inhibitors. This review presents recent advancements in macrocycles and natural biopolymers as green corrosion inhibitors. In addition, related reports on biopolymer nanoparticles and various nanocomposites are presented. The importance of molecular structure and chemical functionalization in the inhibition is debated. The results of computational and theoretical studies are discussed.