A study on the inhibition of mild steel corrosion in hydrochloric acid environment by 4-methyl-2-(pyridin-3-yl)thiazole-5-carbohydrazide

A new nicotinonitrile derivative, namely 4-methyl-2-(pyridin-3-yl)thiazole-5-carbohydrazide (MPTC), was synthesized and the chemical structure was elucidated using Fourier Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR) and elemental analysis (CHN). The anticorrosion properties of the new synthesized compound MPTC toward mild steel in 1M HCl solutions have been investigated using weight loss and scanning electron microscopy (SEM) techniques. The inhibitor concentrations were 0.1 mM to 0.5 mM and the temperatures ranged within 303 to 333 K. The inhibition efficiency increased with an increase in the inhibitor concentration and reached 95.1% at the concentration of 0.5 M and 303 K. Inhibition efficiency increased in parallel with increasing inhibitor concentration and decreased with rising temperature. The inhibition process was attributed to physical adsorption. The results obtained from the usage techniques show that new synthesized inhibitor could serve as an efficient corrosion inhibitor of mild steel in strong acid environment. The investigated inhibitor obeys the Langmuir adsorption isotherm equation. It was found that the corrosion inhibition performance depends on the concentration of the studied inhibitor and the solution temperature. Quantum chemical calculations have been done to correlate the electronic characteristics of the synthesized inhibitor with the corrosive inhibitive impact. Experimental and theoretical results are in good agreement.