One-pot synthesis of N'-(thiophen-2-ylmethylene)isonicotinohydrazide Schiff-base as a corrosion inhibitor for C-steel in 1 M HCl: Theoretical, electrochemical, adsorption and spectroscopic inspections

Although carbon steel (CS) is an essential component utilized in many industries, it regrettably corrodes when exposed to acidic conditions. Schiff bases have recently become more concerned with the corrosion prevention of CS. Hydrazides and the related compounds shown to be effective inhibitors of CS corrosion in acids. These compounds are commonly employed as origins or intermediates to several key molecules in the synthesis of organic compounds, and they are highly sought after due to their wide range of biological and therapeutic applications. They have anti-bacterial, anti-malarial, anti-fungal, and anticancer properties, as well as corrosion protection. Hence, the inhibitory effectiveness of a new synthesized (E)-N'-(thiophen-2-ylmethylene) isonicotinohydrazide (TMNH) Schiff-base for the corrosion of CS in 1 M HCl was explored. The structure of TMNH was validated by FT-IR and 1H NMR spectroscopy. A number of chemical, spectral, and electrochemical techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and mass loss (ML) have been used to evaluate its anticorrosion power. PDP measurements showed that it is a mixed-type inhibitor. In addition, EIS measurements showed that Rctincreased sharply from 37 without the corrosion inhibitor to 589 Omega cm-2 in the presence of 1 mM TMNH and from PDP scans, the corresponding icorrdecreased dramatically from 0.6158 to 0.0314 mu A cm-2. ML tests have proven their effectiveness, achieving an inhibitory efficiency of 95.3%. Adsorption studies were also conducted to determine the nature of the corrosion retardation mechanism. The TMNH inhibitor was spontaneously chemically/physically adsorbed onto the CS surface following the Langmuir isotherm. Statistical calculations were also applied to verify the accuracy of the experimental results. The Monte Carlo model showed that the inhibitory molecules adsorbed flat on only one side, increasing the chances of adsorption.