Review of Tannic Acid’s Effect as a Corrosion Inhibitor for Different Metal Substrates

One of the methods of corrosion protection in different environments is the use of corrosion inhibitors. These materials can be adsorbed physically, chemically, or both on the surface active areas and prevent metal dissolution. Some inhibitors such as nitrates and chromates are compounds that have been used widely for this purpose and have produced favorable results. But today the use of these compounds is limited and in many cases prohibited due to their high toxicity and environmental problems. In this regard, the use of green inhibitors is one of the alternative methods of toxic compounds that has been considered due to its environmental compatibility and cheapness in recent years. Tannic acid is a natural, non-toxic and environmental friendly inhibitor. It is adsorbed to the surface physically and chemically by environmental conditions. In this review article, a summary of studies are reported on the applications of this chemical compound, including its use as a corrosion inhibitor, rust converter, and anti-corrosion pigment. Research results show that in the Inhibition behavior of tannic acid affects factors such as the pH environment, aggressive ions and the type of metal and this compound increases corrosion resistance under various conditions. The use of this material as a rust converter transforms the rusted metal surface into a durable protective layer. Also, the use of hybrid pigment of tannic acid and metals such as zinc in the coating structure improves the corrosion protection and adhesion properties of the coating.