In silico investigations of alginate biopolymer on the Fe (110), Cu (111), Al (111) and Sn (001) surfaces in acidic media: Quantum chemical and molecular mechanic calculations

Herein, the inhibition behavior of alginate biopolymer with different chain length (fragments) on corrosion of Fe (110), Cu (111), Al (111) and Sn (001) surfaces in acidic medium was investigated using quantum chemical calculations and molecular mechanic methods. Based on HSAB's theory, local and global reactivity indicators of different alginate fragments were calculated using DFF/B3LYP/3-21G method. Molecular mechanic simulations were employed to describe quantitatively and qualitatively the adsorption behavior of the bio-inhibitor on the metal surfaces. As a result, the chain length of alginate and metal nature were considerably affected magnitude and trend of alginate/metal interactions. Gradually as the chain length of the alginate molecule was increased, the binding energy increased. On the other hand, it found that the binding of alginate onto metal surfaces followed this order: Sn (001) < Al (111) < Cu (111) < Fe (110). Additionally, the minimum distance based on the radial distribution function (RDF) analysis between alginate and some aggressive agents for considered surfaces was calculated and discussed. (C) 2020 Elsevier B.V. All rights reserved.