Corrosion inhibition of mild steel by collagen derived from fish scales: Experimental and computation studies

This study investigates the effect of collagen as a green corrosion inhibitor of mild steel in saline solution. Collagen derived from Carp fish scale was characterized by the use of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). Long term coupon tests (weight loss technique) and electrochemical tests were used to determine the corrosion rate (CR) and inhibition efficiency (%IE) of the collagen at different temperatures – 298K, 303K and 308K; and different inhibitor amounts - 2g, 4g and 8g. Adsorption studies were performed in order to determine the adsorption parameters and energy. The Scanning electron microscope (SEM) was used to study the surface of the mild before and after the corrosion tests. Molecular dynamics (MD) was performed in order to study the interaction of the inhibitor with the metal surface by using Material studio software (2020), applying the Forcite module, COMPASS forcefield simulation. The results proved for collagen to be a good inhibitor for mild steel with a maximum %IE of 96% achieved at pH 7.5 solution with 8g inhibitor. The adsorption isotherm analysis shows that collagen conformed to Langmuir isotherm with the increase of inhibitor concentration showing an increase in inhibition efficiency, while the increase in temperature showed a decline to the inhibition efficiency. The results from molecular dynamics established correspondence of the interaction and binding energy to the experimental results.