Experimental/computational assessments of API steel in 6 M H2SO4 medium containing novel pyridine derivatives as corrosion inhibitors

Abstract In this work, two pyridine derivatives were synthesized and explored their inhibitive influence on the API carbon steel corrosion in a 6 M H2SO4 solution. The compound was examined at different concentrations to optimized the best concentration for the corrosion inhibition effect. Gravimetric measurements, potentiodynamic polarization measurement (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and theoretical methods were used to evaluating the inhibition efficiency. The obtained adsorption data achieved the model of Langmuir isotherm. The PDP tests proposed that pyridine derivatives are mixed-type inhibitors. The EIS parameters demonstrate that the double-layer capacitance (Cdl) decreases with the increase of inhibitor concentration, which implies a reduces dielectric constant. The parameters derived from the theoretical quantum chemical calculations were found adequately correlated with the obtained experimental results.