Synthesis of a novel pyrazole heterocyclic derivative as corrosion inhibitor for low-carbon steel in 1M HCl: Characterization, gravimetrical, electrochemical, mathematical, and quantum chemical investigations

Abstract

A novel organic corrosion inhibitor, named 3, 5-dimethyl-1H-pyrazol-1-yl m (4-((4-hydroxybenzylidene) amino) phenyl) methanone (DPHM) has been effectively synthesized and characterized. The diagnosis of functional groups and constituents of DPHM has been conducted by FTIR, 1H NMR, and 13C NMR. The inhibitor efficacy for low-carbon steel in 1 M HCl was evaluated by using weight loss and electrochemical techniques. The inhibition efficiency was increased with increasing the temperature and DPHM concentrations. The inhibition efficiency approaches a maximum value of 89.5% at 400 ppm of DPHM and 60 °C. The efficiency of the inhibitor was attributed to the formation of a protective mono-layer on the steel surface. The Langmuir adsorption isotherm was used to inspect the adsorption process mechanism. Theoretical quantum chemical simulations were used to investigate the mechanism of inhibition. The results revealed that the DPHM was the donor of electron, while the steel surface was an electron acceptor. Mathematical and statistical modelling were used as powerful tool for data representation. Exponential model, with 0.992 correlation coefficient, was the most accurate one.