Gravimetric and electrochemical evaluation of three nonionic dithiol surfactants as corrosion inhibitors for mild steel in 1 M HCl solution

At three different temperatures 25, 40 and 55 degrees C, three newly dithiol nonionic surfactants were evaluated as corrosion inhibitors for mild steel in 1 M HCl. Three different techniques were used for evaluation; weight loss at the three different temperatures, the potentiodynamic and impedance methods were studied at 25 degrees C. From the obtained results, the synthesized dithiol surfactants have good inhibition efficiency and significantly increase by increasing the concentration. Increasing temperatures show two different trends; at low concentration, the efficiencies decrease, while at higher concentration the efficiencies increase for the three surfactants. From the electrochemical polarization data, the prepared dithiol surfactant behaves as a mixed-type of inhibitors for carbon steel in 1 M HCl. Double-layer capacitances obtained from electrochemical impedance of synthesized surfactant decrease compared to the blank one when they be added due to the adsorption process to the metal steel surface. The Villamil adsorption isotherm was found to be the more fitted model describing the adsorption process. (C) 2016 Elsevier B.V. All rights reserved.