Electrochemical, spectroscopic and theoretical studies for acid corrosion of zinc using glycogen

Pais, Mikitha and Padmalatha, * (2021) Electrochemical, spectroscopic and theoretical studies for acid corrosion of zinc using glycogen. Chemical Papers, 75 (1387). pp. 1387-1399. ISSN 0366-6352

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Abstract

The objective of the work is to introduce and establish anticorrosion capabilities of a novel biopolymer glycogen (GLY)against sulfamic acid (NH2SO3H) induced corrosion of zinc. The corrosion and inhibition studies were done by electrochemical techniques such as potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy technique (EIS). Conditions were optimized to get maximum inhibition efciency by varying the concentration of the inhibitor in the temperature range of 303–323 K. Activation and thermodynamic parameters were evaluated and discussed in detail. Suitable adsorption isotherm was proposed to ft the experimental results. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and atomic force microscopy (AFM) studies were performed before and after the addition of inhibitor. Adsorption of inhibitor was further confrmed by UV–Visible spectroscopy. Quantum chemical calculations were done to establish the correlation between the structure of the inhibitor and its inhibition efciency. Energy of HOMO, LUMO, energy gap ∆E, dipole moment (µ) Mullikan charges were calculated. Diferent theoretical factor descriptors like the hardness (η), and softness (σ) electronegativity (χ), global electrophilicity (ω), nucleophilicity (ε) and fraction of electron transferred (ΔN) were calculated. Inhibition efciency of glycogen increased with increase in its concentration and with temperature. Maximum efciency of 72% could be achieved for the addition of 0.05 g L−1 of GLY at 323 K. Results were ftted into Langmuir adsorption iostherm. The surface of the metal turned visibly smoother in the presence of GLY. In addition the EDX studies showed increase in carbon content which re-afrmed the adsorption of GLY on the metal surface. The density functional theory (DFT) based theoretical studies supported the experimental observations.

Item Type: Article
Uncontrolled Keywords: Glycogen · Corrosion inhibition · Electrochemical studies · surface morphology · Adsorption studies · Theoretical studies
Subjects: Engineering > MIT Manipal > Chemistry
Depositing User: MIT Library
Date Deposited: 11 Jun 2021 09:13
Last Modified: 11 Jun 2021 09:13
URI: http://eprints.manipal.edu/id/eprint/156793

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