Inhibitive effect of thiosemicarbazone derivative on corrosion of mild steel in hydrochloric acid solution

Inhibition effect of 3-pyridinecarboxaldehyde thiosemicarbazone (META) on the mild steel corrosion in one molar hydrochloric acid was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that (META) is an effective inhibitor for mild steel corrosion in 1.0 M HCl solutions and inhibition efficiency is >94% at inhibitor concentration of 0.01 M. Adsorption of the inhibitor on the mild steel surface followed Langmuir adsorption isotherm. The thermodynamic values indicated that adsorption of 3-pyridinecarboxaldehyde molecule is a spontaneous process and it adsorbs chemically as well as physically. Polarization studies showed that 3-pyridinecarboxaldehyde is a mixed-type inhibitor. Scanning electron microscope (SEM) micrographs revealed that inhibition occurs due to adsorption of 3-pyridinecarboxaldehyde molecules at metal/solution interface.