Corrosion behaviour of mild steel in 0.5 M sulphuric acid media in the presence of potassium chromate

Abstract

This research investigates the behaviour of K2CrO4 on mild steel corrosion in 0.5 M H2SO4 at ambient temperature of 30'C. The study was conducted using weight loss and potentio-dynamic polarization measurements. Data were recorded from the weight loss tests while the readout from the potentiostat was documented. Adsorption studies were also carried out. Furthermore, an investigation was conducted using surface coverage against concentration plot to determine when the best surface would be obtained during the experiment. Results from the study revealed that inhibitor efficiency increased as inhibitor concentration increased. The potentio-dynamic polarization plot also identified the inhibition mechanism of action as mixed but predominantly anodic type inhibition with maximum Ecorr displacement of 68 mV. The adsorption of the inhibitor agrees with the Langmuir adsorption isotherm while the separation factor which is a component of the Langmuir expression showed a favourable adsorption. The Gibbs free energy of adsorption showed negative value (-9.8 kJ/mol) depicting a spontaneous process with a prevalence of physical adsorption. The first day curve showed the best surface coverage values across all inhibitor concentrations utilized.