Experimental and theoretical study of corrosion inhibition of 3-pyridinecarbozalde thiosemicarbazone for mild steel in hydrochloric acid

•The studied inhibitor contains both pyridine ring and Schiff base structure.•3-PCT shows excellent inhibitive properties for mild steel in HCl solution.•The results of MD simulation reveal that 3-PCT molecules adsorb on the iron surface with a nearby flat orientation.•The PZC measurement showed the mild steel surface was positively charged in HCl. The corrosion inhibition effect of 3-pyridinecarboxaldehyde thiosemicarbazone (3-PCT) on mild steel was studied in 1M HCl solution by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The surface morphology of mild steel was examined with scanning electron microscopy (SEM) and the mechanism of inhibition was determined by the potential of zero charge (PZC) measurement at the metal–solution interface. Then molecular dynamics simulations were also executed for 3-PCT. The results show that 3-PCT is a good corrosion inhibitor, retarding both cathodic and anodic reactions in hydrochloric acid. The adsorption of 3-PCT on the mild steel surface obeys the Langmuir isotherm, and the thermodynamic parameters (Kads,Ea,ΔGads0) were also determined and discussed.