Chapter20 - Carbohydrates as green corrosion inhibitors

Abstract

Nonpolymeric carbohydrates such as glucose and glucosamine and their derivatives are evaluated as corrosion inhibitors for various metal/electrolyte systems. Their corrosion inhibition performances are tested using various experimental and computational techniques. They serve as effective and environmental friendly alternatives for traditional toxic corrosion inhibitors. Potentiodynamic polarization measurement reveals that most of such compounds become effective by suppressing both anodic and cathodic Tafel reactions without causing any significant variation in the value of corrosion potential, Ecorr. They act as mostly mixed-type corrosion inhibitors however cathodic predominance has also been reported in few reports. They behave as interface-type corrosion inhibitors as they increase the value of charge transfer resistance in their presence. Adsorption of these compounds on the metallic surface mostly follows the Langmuir adsorption isotherm. Adsorption mechanism of corrosion inhibition using non-polymeric carbohydrates has also been supported by surface investigations, especially through SEM, AFM, XPS, FT-IR, contact angle, and EDX analyses. DFT and MD (or MC) simulation studies are widely used to demonstrate the nature and effectiveness of interactions between non-polymeric carbohydrates and metallic surface. These analyses show that most of the non-polymeric carbohydrates and their derivatives spontaneously interacted through donor-acceptor interactions. Substituents greatly affect the orientation and effectiveness of these molecules adsorption on the metallic surface.