Document Type: Research Paper
Department of Chemical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran
Corrosion can cause dangerous and expensive damage to everything from pipelines to vehicles, water and wastewater systems, and even home appliances. The use of organic inhibitors is one of the most widely practical methods for protection of metals and alloys against corrosion. The inhibition ability of 2-Mercaptobenzothiazole as an inhibitor against the corrosion of C-steel in 2 M NaCl solution was evaluated by Tafel polarization. 2-Mercaptobenzothiazole retards both the cathodic and anodic reaction through chemical and physical adsorption and blocking the active corrosion sites. Polarization curves showed that the inhibition efficiency increases up to 70% with increase in inhibitor concentration in room temperature and increase with rise in temperature. The adsorption of 2-Mercaptobenzothiazole obeyed the Langmuir adsorption isotherm. The enthalpies of activation were calculated around +50 kj mol-1. The positive signs of the enthalpies of activation process ΔH reflect the endothermic nature of the steel dissolution process. The calculated 〖∆G〗_ads values are ranging between -32.69 and -35.81 kJ mol_1, indicating that the adsorption mechanism is both electrostatic adsorption and chemisorption. The entropy of adsorption was calculated 78 j mol-1 K-1 which indicated the increase in the solvent entropy and more positive water desorption entropy.