Abstract
The inhibition effect of the green inhibitor Polyvinyl pyrrolidone (PVP) on the corrosion of carbon steel (C-steel) in 2 M HCl aerated unstirred solutions is investigated. Electrochemical methods (EIS and potentiodynamic polarization) and gravimetric methods are applied to study the corrosion of C- steel with PVP over a range of concentrations and temperatures. The polarization method indicates that PVP behaves as a mixed-type inhibitor. The impedance method reveals that the charge transfer process is dominant in controlling the corrosion of C-steel. The inhibition efficiencies ranged from 56-83%, as determined by weight loss, and from 60-90%, as determined by electrochemical methods. The different techniques used confirm the adsorption of PVP on the C-steel surface and consequently the inhibition of the corrosion process. The adsorption of PVP on the C-steel surface is found to obey the Langmuir adsorption isotherm. A mechanism is proposed to explain the inhibitory action of PVP. The thermodynamic parameters for the adsorption of PVP on the C-steel surface show a decrease in Eapp , AH and AS. The inhibition efficiency of PVP increases with increasing inhibitor concentration and increasing temperature.