*11.5.4.8 Green corrosion inhibitors*

There is no clear and accepted definition of "environmentally friendly" or "green" corrosion inhibitors. In practice, corrosion inhibition studies have become oriented towards human health and safety considerations. For this purpose recently, the researchers have been focused on the use of eco-friendly compounds such as plant extracts, expired nontoxic medicines, etc. which contains many organic compounds [59–61]. Amino acids, alkaloids, pigments and tannins are used as green alternatives for the toxic and hazardous compounds. Due to biodegradability, eco-friendliness, low cost and easy availability and the extracts of some common plants and medicinal plant and its products have been studied as corrosion inhibitors for various metals and alloys under different environmental conditions.
