Use of natural gums as green corrosion inhibitors: an overview

Corrosion of metals and its alloys employed in service is an inescapable but a controllable process. One of the practical methods for controlling the impact of corrosion of metals and alloys especially in aqueous environments is by using corrosion inhibitors which are composed mainly of organic or inorganic substances. However, the toxicity of organic and inorganic corrosion inhibitors to the environment and humans has compelled the search for safer corrosion inhibitors called 'green corrosion' inhibitor due to their properties like non-toxicity, biodegradability, and low cost. The use of natural gums as environmentally safe corrosion inhibitor for metal and alloys has in recent times received tremendous attention by several researchers. Also quantitative structure activity relationship approach has been used to establish the correlations between a number of quantum chemical parameters and the molecular structures of some gum extracts major components. This approach has aided in understanding the component of the gum extracts responsible for imparting the inhibition effect since there are several components of the gum which could act in synergy to inhibit the metal corrosion. This review paper presents an overview of works published on natural gums as green corrosion inhibitors. It also discusses the use of computational chemistry tools in understanding the inhibition mechanism of gum extracts components which is often difficult to determine using experimental means.