Corrosion inhibition properties of the combined admixture of thiocarbanilide and hexadecyltrimethylammoniumbromide on mild steel in dilute acid solutions

Abstract The synergistic effect of the combined admixture of thiocarbanilide and hexadecyltrimethylammoniumbromide on the electrochemical corrosion behavior and inhibition of mild steel in 1 M H2SO4 and HCl acid media was evaluated through weight loss analysis, potentiodynamic polarization technique, and IR spectroscopy. Results show that the admixture performed effectively in both acid solutions with an average HTH inhibition efficiency of 86.2 and 82% in H2SO4 acid from weight loss and potentiodynamic polarization test while the corresponding values in HCl acid are 79 and 80%, respectively. Thermodynamic calculations showed that the compound chemically adsorbed onto the steel surface blocking the diffusion of corrosive anions and simultaneously suppressing the redox electrochemical process responsible for corrosion. Infrared spectroscopic images revealed the presence of the functional groups of the organic compound responsible for corrosion inhibition. Statistical derivations through Analysis of variance analysis confirmed that the inhibitor concentration is the only variable responsible for the inhibition efficiency values. Adsorption of the compound obeyed the Langmuir isotherm model.