Eco-Friendly Metal Corrosion Inhibitors Based on Natural Polymers (A Review)

The promising eco-friendly corrosion inhibitors based on natural polymers are analyzed. The anticorrosion effectiveness of biopolymers, which in particular include, chitin, starch and inulin, widely used in industry in various corrosive environments, is considered. The main methods of researching the inhibitory efficiency of natural polymers on the surface of metals and alloys are described, including gravimetry, cyclic voltammetry, electrochemical impedance spectroscopy, adsorption isotherms, and quantum chemical approaches. The effectiveness of corrosion inhibition by polymers is influenced mainly by their concentration, molecular weight and structure, and the protection mechanism is generally caused by the adsorption due to the presence of polar functional groups in them. These functional groups cause the blocking of the corrosive medium access to the metal surface. The protective properties of natural gums and the main mechanisms of their inhibition of carbon steels and aluminum alloys corrosion are considered. The data on the anti-corrosion effect of inhibitory synergistic compositions based on natural polymers, which are characterized by the synergism of the components, are given. The creation of synergistic compositions is an effective way to improve the protective effect of polymers, to reduce their concentration and to diversify applications in corrosive environments.