Nicotinic acid derivatives as corrosion inhibitors for mild steel in hydrochloric acid solutions: an experimental and computational chemistry study

Abstract

The inhibition performance and mechanism of nicotinic acid (NA), nicotinic acid amide (NAA) and 4-methoxypyridine (MP) for the corrosion of mild steel in 0.5 M HCl solution were investigated and compared by means of experimental tests, including potentiodynamic polarization and electrochemical impedance spectroscopy measurements, surface analyses and quantum chemistry calculation. The electrochemical results show that the inhibition efficiencies of the three inhibitors increase with the concentration and decrease with the temperature. The NAA and MP inhibitors exhibit the highest and lowest efficiency and activation energy for the corrosion process, respectively, which is confirmed by the corrosion morphology observation. Fourier transform infrared analysis and X-ray photoelectron spectroscopy (XPS) analysis confirm the spontaneous adsorption of all three inhibitors on the surface. The adsorption analysis demonstrates that the adsorption process follows Langmuir model and consists of both physisorption and chemisorption. The quantum chemistry calculation correlates the molecular structures and charge density distributions with the corrosion inhibition efficiencies of NAA, NA and MP inhibitors, and further proves that the good inhibition performance of NAA inhibitor originates its high adsorption ability.

Keywords:

• Corrosion inhibitor
• nicotinic acid derivatives
• electrochemical study
• quantum chemistry calculation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors would like to acknowledge the financial supports from Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province (No. 2017CL18).