ABSTRACT
Most of the metals and alloys are prone to corrosion in acidic and / or alkaline environments. Control of corrosion is critical to impede the deterioration effects of corrosion. Green materials are beneficial for corrosion protection regarding the issues of environment, toxicity and availability. Therefore, biopolymers-based materials are used as corrosion inhibitors in the corrosive environment for corrosion protection by being included in the coating. This chapter will focus on natural inhibitors by comparing them to organic synthetic inhibitors. The discussion will cover three groups of natural polymers that are polysaccharides / biopolymers, proteins and polyesters. In addition, the chapter provides a generic overview of the adsorption mechanisms of the inhibitors, the methods of measuring corrosion efficiencies and comments about the corrosion efficiencies. It also addresses some important parameters such as the type and the concentration of the corrosion inhibitor, acidity and the temperature of the corrosive medium and their effects on the corrosion inhibition efficiency of the natural inhibitors.
