Impact of cinnamaldehyde thiosemicarbazone on the corrosion of mild steel in 1 M and 15% HCl

The present work highlights the impact of cinnamaldehyde thiosemicarbazone (CT) as a corrosion inhibitor (CI) on the deterioration of mild steel (MS) in 1 M and 15% HCl. The synthesis of CT was accomplished with the help of cinnamaldehyde and thiosemicarbazide using Schiff-base chemistry, and the product's structure was verified by 1H- Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy. The anti-corrosion performance of CT was performed on the MS using gravimetric methods, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization studies (PDP). The experimental results of the CT molecule's adsorption on an MS surface in 1 M and 15% HCl align with the Langmuir adsorption isotherm. The EIS study shows that as the CT concentration increases, charge transfer resistance increases with 93.18% (using 1 mM of CT) and 97.63% (using 4 mM of CT) corrosion inhibition efficiency (IE) in 1 M and 15% HCl, respectively. PDP suggests that CT works as a mixed-type inhibitor as CT suppresses both anodic and cathodic reactions. The gravimetric analysis confirmed that the developed CT exhibited 95.02% (using 1 mM of CT) and 96.65% (using 4 mM of CT) corrosion inhibition efficiency (IE) in 1 M and 15% HCl at 303 K, respectively. But at 343 K, in 1 M and 15% HCl, the anti-corrosion performance of CT on MS was reduced to 86.74% and 92.50%, respectively. The Experimental results were consistent with the theoretical results with the help of DFT. The surface morphology of the sample was examined under FE-SEM.